Cephalopods from the Cretaceous/Tertiary Boundary Interval on the Atlantic Coastal Plain, with a Description of the Highest Ammonite Zones in North America

PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024 Number 3454, 64 pp., 22 ®gures, 2 tables August 23, 2004

Cephalopods from the Cretaceous/Tertiary Boundary Interval on the Atlantic Coastal Plain, with a Description of the Highest Ammonite Zones in North America. Part 1. Maryland and North Carolina

NEIL H. LANDMAN,1 RALPH O. JOHNSON,2 AND LUCY E. EDWARDS3

ABSTRACT

The sedimentary deposits on the Atlantic Coastal Plain in New Jersey, Delaware, Maryland, North Carolina, South Carolina, and Georgia span the Cretaceous/Tertiary boundary. We in- vestigate the ammonites of the Severn Formation on the western and eastern shore of Ches- apeake Bay, Maryland, and the Peedee Formation, North Carolina. We describe three ammonite assemblages from the Severn Formation and their associated dino¯agellates, de®ning three successive ammonite zones in the upper Maastrichtian. The lowest ammonite zone is the Discoscaphites conradi Assemblage Zone. It occurs near the top of the Severn Formation in Prince Georges County, Maryland, just below the Paleocene Brightseat Formation. The ammonite fauna consists of Sphenodiscus pleurisepta (Conrad, 1857), Sphenodiscus lobatus (Tuomey, 1856), Discoscaphites conradi (Morton, 1834), Discoscaphites gulosus (Morton, 1834), Jeletzkytes nebrascensis (Owen, 1852), Glyptoxoceras rugatum (Forbes, 1846), Bacu- lites vertebralis Lamarck, 1801, and Eubaculites latecarinatus (Brunnschweiler, 1966). Di- no¯agellates from a sample of matrix include Isabelidinium aff. I. cooksoniae (Alberti, 1959) Lentin & Williams, 1977, which correlates with calcareous nannofossil Zone CC25b, indicating the lower part of the upper Maastrichtian (68.2±67.4 MaBP). The D. conradi Zone is also present in parts of the Corsicana Formation, Texas, the Prairie Bluff Chalk, Alabama and

1 Division of Paleontology (Invertebrates), American Museum of Natural History ([email protected]). 2 Monmouth Amateur Paleontologist's Society, 57 Oceanport Avenue, West Long Branch, NJ 07764 (paleotrog@ webtv.net). 3 U.S. Geological Survey, Mail Stop 926A, Reston, VA 20192 ([email protected]).

Mississippi, the Peedee Formation, North Carolina, and the Navesink and New Egypt For- mations, New Jersey. The next higher zone is the Discoscaphites minardi Assemblage Zone, which occurs in the Severn Formation approximately 6 m below the base of the Hornerstown Formation at Lloyd Creek, Kent County, Maryland. The ammonite assemblage is dominated by Discoscaphites minardi, n.sp., B. vertebralis, and S. pleurisepta, with rare specimens of Sphenodiscus sp., Discoscaphites iris (Conrad, 1858), and E. latecarinatus. A sample of dino¯agellates from the same bed as the ammonites includes De¯andrea galatea (Lejeune- Carpentier, 1942) Lentin & Williams, 1973 and Thalassiphora pelagica (Eisenack, 1954) Ei- senack & Gocht, 1960, which correlate with the Neophrolithus frequens calcareous nannofossil Zone between Subzones CC26a and CC26b, indicating the middle part of the upper Maastrich- tian (66.4±66.0 MaBP). The D. minardi Zone is also present in the New Egypt Formation, New Jersey. The highest zone is the D. iris Assemblage Zone, which occurs near the top of the Severn Formation at its type locality at Round Bay, Anne Arundel County, Maryland. The ammonite assemblage is dominated by D. iris and E. carinatus, although elsewhere this zone also includes Pachydiscus (Neodesmoceras) mokotibensis Collignon, 1952, Pachydiscus (Pachydiscus) jacquoti jacquoti Seunes, 1890, S. lobatus, S. pleurisepta, Discoscaphites sphaeroidalis Kennedy and Cobban, 2000, and E. latecarinatus. Dino¯agellates from a sample of matrix surrounding one of the ammonites include Palynodinium grallator Gocht, 1970 and T. pelagica indicative of the P. grallator Zone, Tpe subzone, which correlates with the upper part of calcareous nannofossil Zone CC26b, indicating the upper part of the upper Maastrich- tian (65.6±65.0 MaBP). The D. iris Zone is also present in the upper part of the Corsicana Formation, Texas, the Owl Creek Formation, Mississippi, Tennessee, and Missouri, and the New Egypt and Tinton Formations, New Jersey.

INTRODUCTION and Anne Arundel County. The succession of ammonite assemblages in the Severn For- The Cretaceous and Cenozoic strata of the mation de®nes three ammonite zones that Atlantic Coastal Plain crop out as a narrow, span the upper Maastrichtian. The dino¯a- irregular belt east of the Piedmont Plateau. gellates associated with the ammonites per- These outcrops have been extensively stud- mit correlation of these zones with the estab- ied because they contain the Cretaceous/Ter- lished biostratigraphic zonation of calcareous tiary boundary interval (e.g., Olsson, 1963, nannofossils. 1975; Olsson and Wise, 1987; Olsson et al., 1988; Jordan, 1963, 1976; Minard et al., LIST OF LOCALITIES 1969; Owens et al., 1970, 1977; Wheeler and Curran, 1974; Gallagher, 1986, 1991, 1993; Numbers in parentheses indicate U.S. Gallagher and Parris, 1985; Gallagher et al., Geological Survey Paleobotanical localities 1986). They are especially relevant today in (®g. 1). light of recent evidence of an asteroid impact AMNH loc. 3252 (R6235). Upper part of at the end of the Cretaceous that produced a Severn Formation, cutbanks along Lloyd mass extinction. We have explored these out- Creek, 0.9 mi (1.4 km) east±northeast of crops with the hope of discovering ammo- Stillpond, Kent County, Maryland. nites to elucidate the ammonite zonation of AMNH loc. 3260 (R6370). Upper part of the Maastrichtian Stage of the Atlantic Severn Formation, exposures along banks of Coastal Plain, as well as to provide insights a tributary of Cattail Brook, 0.5 mi (0.8 km) into the biogeography and diversity of am- south of the intersection of Sheriff and monites at the close of the Cretaceous. Brightseat roads, near Brightseat, Prince For purposes of organization, we are pub- Georges County, Maryland. lishing our papers as a series treating differ- U.S. Geological Survey Paleobotanical ent geographic regions. In this ®rst paper, we loc. R6374. Upper part of Severn Formation, describe ammonites from the Peedee For- presumed to be from the western shore of the mation in North Carolina and from the Sev- Severn River at Round Bay, Anne Arundel ern Formation at three localities in Mary- County, Maryland. land: Prince Georges County, Kent County, AMNH loc. 3345 (R6234A±D). Top of 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 3

Fig. 1. Maps of parts of New Jersey, Delaware, Maryland, and North Carolina showing localities mentioned in the text. 4 AMERICAN MUSEUM NOVITATES NO. 3454

New Egypt Formation and bottom of Hor- parts of southern Delaware, eastern Mary- nerstown Formation, Parkers Creek, 0.3 km land, and northeastern Virginia. It contains a east of Rt. 35, northwest of Eatontown, Mon- rich molluscan fauna, and in areas that have mouth County, New Jersey. not suffered extensive groundwater leaching, AMNH loc. 3346 (R6234E). Upper part of the fossils preserve their original aragonitic New Egypt Formation, approximately 1.5±2 shell (Hartstein and Decina, 1986; Kennedy m below the base of the Hornerstown For- et al., 1997; Kuehne, 1999). It also contains mation, Parkers Creek, 0.1 km east of Rt. 35, an abundant scrap fauna of marine verte- northwest of Eatontown, Monmouth County, brates, including ®sh, sharks, sea turtles, ple- New Jersey. siosaurs, mosasaurs, and crocodiles, as well Upper part of Peedee Formation, Todd as terrestial and ¯uviatile vertebrates, includ- Marl Pit off Todd Road, approximately 2 km ing soft-shelled turtles and dinosaurs, indi- west of the Shalotte River, Brunswick Coun- cating that the site of deposition was rela- ty, North Carolina. tively nearshore (Baird, 1986; Hartstein and Upper part of Peedee Formation, John D. Decina, 1986). Long County Park, Rt. 33, 1.1 mi (1.8 km) The Severn Formation has been correlated south of Rt. 17, Brunswick County, North with the Navarroan Provincial Stage (Mur- Carolina. ray, 1961; Brouwers and Hazel, 1978). This U.S. Geological Survey loc. 25423. Owl stage is approximately equivalent to the Creek Formation, bluffs on Owl Creek, 3 mi whole of the Maastrichtian Stage as shown (4.8 km) northeast of Ripley, secs. 7 and 8, by Pessagno (1969), but Brouwers and Hazel T4S, R4E, Tippah County, Mississippi. (1978) have pointed out that the upper and lower boundaries of the Navarroan Provin- SEVERN FORMATION cial Stage may not coincide exactly with those of the Maastrichtian. Many studies OVERVIEW have re®ned the age of the Severn Formation The Severn Formation is named for ex- on the basis of a variety of micro- and mac- posures on the Severn River at Round Bay rofossils. However, these studies, which we on the western shore of Chesapeake Bay, review below, are sometimes dif®cult to in- Anne Arundel County, Maryland (Minard et terpret because of changes in biostratigraphic al., 1977). The name Severn Formation re- usage since the studies were completed. Our places the name Monmouth Formation pre- discussion of the Severn Formation is divid- viously proposed by Clark (1916) and Clark ed into three parts, covering, in sequential et al. (1897). The unit is entirely marine and order, Prince Georges, Kent, and Anne Arun- very fossiliferous and consists of dark gray, del Counties, Maryland. ®nely micaceous, sparingly glauconitic, quartz sand (®g. 2). The formation crops out PRINCE GEORGES COUNTY as a narrow, irregular band that extends STRATIGRAPHY AND PALEONTOLOGY southwest-northeast (Glaser, 1968) from Prince Georges County, Maryland, to New Thanks to roadwork and construction ac- Castle County, Delaware (Minard et al., tivities in the past 30 years, many new out- 1977). The formation thins to the southwest; crops of the Severn Formation have been ex- it is a maximum of 24 m thick on the eastern posed in Prince Georges County, Maryland, shore of Chesapeake Bay (Minard et al., and have provided the impetus for renewed 1977), 12.6 m thick at its type locality at research activity. These outcrops include lo- Round Bay on the western shore of Chesa- calities near Brightseat (loc. 1, Brouwers and peake Bay (Minard, 1980), and approximate- Hazel, 1978; loc. A, Baird, 1986), Landover ly 10 m thick in the Brightseat area near the (loc. 2, Brouwers and Hazel, 1978; loc. B, type locality of the Brightseat Formation Baird, 1986), Largo (loc. G, Baird, 1986), (Owens et al., 1977). Oxon Hill (loc. F, Baird, 1986), and Ran- Brouwers and Hazel (1978) interpreted the dolph Village (loc. 3a, Brouwers and Hazel, Severn Formation as having been deposited 1978; loc. C, Baird, 1986). in the Salisbury Embayment, which covered A composite stratigraphic section of the 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 5 Fig. 2. Stratigraphic relationships of Cretaceous and Tertiary formations from Round Bay, Maryland, to Raritan Bay, New Jersey (from Minard, 1980). 6 AMERICAN MUSEUM NOVITATES NO. 3454

Fig. 3. Generalized stratigraphic sections of the Severn Formation at three sites in Maryland. The sections are arranged so that the ammonite assemblages (ϭ zones) appear in ascending stratigraphic order from left to right. The Brightseat section is based on Owens et al. (1977: ®g. 61), the Lloyd Creek section on Minard (1974: pl. 1; 1980) and Minard et al. (1977), and the Round Bay section on Minard (1980: pl. 1). The ammonites from Round Bay were probably collected from a site 2±3 km southwest of the type locality on the west side of the Severn River. According to Owens et al. (1977: ®g. 61), this site is similar to the type locality. The stratigraphic position of the ammonites at Round Bay is shown with a question mark because the position is inferred based on the associated dino¯agellates with reference to the biostratigraphic zonation of the Severn Formation documented by Benson (1976) and Firth (1987).

Severn Formation in Prince Georges County utary of Cattail Branch, near Brightseat (near is illustrated in ®gure 3. The Severn For- AMNH loc. 3260, equivalent to Brightseat mation is approximately 10 m thick and is locality, Gardner, 1916; loc. 1, Brouwers and unconformably underlain by either the Ma- Hazel, 1978) have been described by Kuehne gothy or Matawan Formation, depending on (1999). The sediments consist of dark gray, the site, and is unconformably overlain by micaceous, sandy clay, containing large, either the Brightseat or Aquia Formation, rounded, sideritic concretions. Fossils occur also depending on the site (Cooke, 1952; in the upper 2±3 m at this site and are pre- Glaser, 1968; Whitney, 1984). The upper 2± served with original shell material both in the 3 m of the Severn Formation contain a rich clay and in the concretions. The fauna is very molluscan fauna. rich in molluscs, consisting of 46 bivalve The stream-bank exposures along the trib- species, 54 gastropod species, and 8 cepha- 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 7 lopod species (Kuehne, 1999: 77±78). Atlantic Coastal Plain (Cobban and Kennedy, Owens et al. (1977) noted reworked Creta- 1995; Kennedy et al., 1997). Kennedy et al. ceous fossils at the base of the overlying (1997) correlated this assemblage zone with Brightseat Formation. part or all of the Belemnitella junior and Be- Hartstein and Decina (1986) described a lemnella kazimiroviensis Zones in the north- nearby outcrop of the Severn Formation at a west European succession (®g. 5). According construction site of an industrial park at the to Christensen (1996), as reviewed by Bur- southeast quadrant of the junction of Inter- nett (1998a), these zones are approximately state 95 and Landover Road. The excavations equivalent to the whole of the upper Maas- exposed up to 15 ft (4.6 m) of the Severn trichtian. Kennedy et al. (1997) concluded Formation. Most fossils are well preserved ``that the Severn Formation occupies a ho- and occur in medium to large concretions 2± rizon high in the Maastrichtian, but slightly 6 ft (0.6±1.8 m) below the top of the for- below the top of the stage ...''. mation. Hartstein and Decina (1986: 88, Ta- Sohl (1977: text-®g. 5) and Sohl and Koch ble 1) stated that ``nearly 60 of the more than (1984) studied the molluscs, notably the gas- 100 species of molluscs described from the tropods, from several sites in Prince Georges Severn Formation were relatively common at County near the top of the Severn Formation this site.'' (®g. 4). They identi®ed the Haustator bilira Kuehne (1999: 78) described stream-bank Assemblage Zone of the Gulf and Atlantic exposures at the head of a small ravine 1.5 Coastal Plain. According to Sohl and Koch mi (2.4 km) south of Oxon Hill (site F, Baird, (1984), this zone includes all deposits on the 1986), approximately 15 km southwest of Coastal Plain above the base of the Globo- Brightseat. The Severn Formation consists of truncana gansseri Subzone of Pessagno 2.8 m of medium gray, micaceous, sandy (1969). Following the interpretation of clay overlain by 3.8 m of the Aquia Forma- SchoÈnfeld and Burnett (1991: ®g. 7), this in- tion. Original shell material is preserved in terval (i.e., Cretaceous deposits above the G. the clay and in the concretions. The fauna is gansseri Subzone) is approximately equiva- less diverse than in the Brightseat area and lent to the entire upper Maastrichtian (®g. 5). consists of 37 bivalve species, 13 gastropod Owens et al. (1977) pointed out that the age species, 1 scaphopod species, and 3 cepha- of the lower part of the Severn Formation in lopod species. Prince Georges County is more poorly con- The ammonites from the upper part of the strained. They reported Belemnitella near the Severn Formation in Prince Georges County base of the formation in one outcrop in the (®g. 4) have been described by Clark (1916: Lanham quadrangle, indicating, according to pl. 12, ®g. 1; pl. 13, ®g. 10), Hartstein and them, an older faunal assemblage. Decina (1986: pl. 2, ®gs. 14±16, 18), Land- Brouwers and Hazel (1978) studied the os- man and Waage (1993: ®g. 133), and Ken- tracodes of the Severn Formation from six nedy et al. (1997: ®gs. 1±24). They are abun- localities in Prince Georges County (®g. 4). dant and well preserved and consist of They analyzed 10 samples near Brightseat Sphenodiscus pleurisepta (Conrad, 1857), from the base to the top of the formation, Sphenodiscus lobatus (Tuomey, 1856), Dis- that is, from the contact with the underlying coscaphites conradi (Morton, 1834), Discos- Magothy Formation to the contact with the caphites gulosus (Morton, 1834), Jeletzkytes overlying Brightseat Formation. They treated nebrascensis (Owen, 1852), Baculites verte- the ostracodes from all six localities as a sin- bralis Lamarck, 1801, Eubaculites latecari- gle assemblage and compared it with the bio- natus (Brunnschweiler, 1966), and Glyptox- stratigraphic distribution of ostracodes in oceras rugatum (Forbes, 1846). correlative formations on the Gulf and At- lantic Coastal Plain. They concluded that the AGE AND CORRELATION Severn Formation in Prince Georges County correlates with part of the Globotruncana The ammonites from the Severn Forma- gansseri Subzone of Pessagno (1969), tion in Prince Georges County represent the which, in terms of today's usage, is approx- D. conradi Assemblage Zone of the Gulf and imately equivalent to the lower part of the 8 AMERICAN MUSEUM NOVITATES NO. 3454 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 9 upper Maastrichtian (SchoÈnfeld and Burnett, I. cooksoniae (Alberti, 1959) Lentin & Wil- 1991) (®g. 5). liams, 1977. Brouwers and Hazel (1978) cited two other studies that corroborated their results. C.C. LLOYD CREEK,KENT COUNTY Smith (personal commun., 1976, in Brou- wers and Hazel, 1978) analyzed nannofossils STRATIGRAPHY AND PALEONTOLOGY from one locality in the Severn Formation in Prince Georges County (locality 3b, Brou- Minard (1974) studied the stratigraphy of wers and Hazel, 1978), presumably from the the Betterton quadrangle in Kent County, upper part of the unit (®g. 4). He suggested Maryland, on the eastern shore of Chesa- that the Severn Formation correlates with the peake Bay, where he identi®ed what he G. gansseri Subzone of Pessagno (1969), called the Mount Laurel Sand. He described that is, the lower upper Maastrichtian (®g. 5). it as a thick unit of glauconitic quartz sand F.E. May (personal commun., 1976, in Brou- lying between the Marshalltown Formation wers and Hazel, 1978) analyzed the dino¯a- below and the Hornerstown Formation gellates from the same locality as Smith and above. He described the Mount Laurel/Hor- concluded that the formation correlates with nerstown formational contact as unconform- the Belemnitella lanceolata±B. occidentalis able and spanning the Cretaceous/Tertiary Zone and/or with the lower part of the B. boundary. Reminiscent of Hornerstown con- occidentalis Zone of the type Maastrichtian tacts elsewhere, Minard (1974: 11) wrote that (®gs. 4, 5). According to Brouwers and Ha- ``The green, very glauconitic Hornerstown zel (1978), citing Berggren (1964), this zone lies directly on the brown to gray, sparingly is approximately equivalent to the G. gans- glauconitic quartz sand of the Mount Laurel. seri Subzone of Pessagno (1969), that is, the In some outcrops, glauconite ®lled borings lower upper Maastrichtian. extend downward from the basal Horners- town into the Mount Laurel.'' In a core-hole drilled near Chesterville, Kent County, Han- NEW OBSERVATIONS sen (1992) reported that the contact was A grain size analysis of the sediments sharp with 0.5 in. (1.3 cm) of relief. from AMNH loc. 3260 near Brightseat, Subsequently, Minard et al. (1977) and Prince Georges County, reveals that nearly Minard (1980) reinterpreted the upper part of one-half (48%) of the sediments are sand, al- the Mount Laurel Formation in the Betterton most evenly divided between very ®ne quadrangle as part of the Severn Formation (0.0625 mm Յ x Ͻ 0.125 mm) and ®ne (®g. 2). According to Minard et al. (1977), (0.125 mm Յ x Ͻ 0.25 mm) grain fractions. the Severn Formation is approximately 24 m Quartz is the dominant mineral (52%), with thick in this area and is bounded below by glauconite and mica representing much very coarse quartz sand with granules and smaller proportions, 6% and 5%, respective- small pebbles (®g. 3). In contrast, Hansen ly. (1992) reported a thickness of only 14 ft (4.8 The matrix in the body chamber of m) in his core near Chesterville. AMNH 47478, a specimen of Sphenodiscus Minard (1974) noted the presence of fos- lobatus from AMNH loc. 3260 (R6370), was siliferous beds of Maastrichtian age, which analyzed for dino¯agellates (table 1, ®gs. 6, occur locally at the top of the Severn For- 7). The preservation is good, the diversity is mation, especially in the northeastern part of moderate, and no single species dominates. the Betterton quadrangle (®gs. 4, 5). He de- The ¯ora notably includes Isabelidinium aff. scribed these beds as medium gray to medi-

← Fig. 4. Approximate stratigraphic positions of samples from the Severn Formation in Prince Georges, Kent, and Anne Arundel Counties, Maryland, used in various studies to determine the biostratgraphic position of the Severn Formation. The samples are plotted on a generalized stratigraphic section for each area (®g. 3). 10 AMERICAN MUSEUM NOVITATES NO. 3454 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 11 um dark gray, silty to clayey, glauconitic, mation at Chesterville, Kent County. Two quartz sand with some mica and feldspar. samples were analyzed, one from near the The contact with the overlying Hornerstown bottom, and the other from near the top of Formation was not visible at these outcrops the formation (®g. 4). Olsson (in Hansen, and he did not indicate the distance of these 1992: appendix D) studied the foraminifera beds below the base of the Hornerstown For- and assigned the upper sample to the upper mation. However, Minard (1974, pl. 1) illus- Maastrichtian and the lower sample to the trated a fossiliferous layer approximately 6 Maastrichtian (®g. 5). Brenner (in Hansen, m below the base of the Hornerstown For- 1992: appendix C) studied the dino¯agel- mation in his stratigraphic column, which lates, pollen, and spores, and assigned the presumably represents this horizon. lower sample to the Maastrichtian (the upper Minard (1974) reported that fossils were sample was barren) (®g. 5). Gohn (in Han- abundant and included bivalves such as Cu- sen, 1992: appendix B) studied the ostra- cullaea and Cardium, gastropods such as codes and concluded that both samples Haustator bilira (Stephenson, 1941), and ranged from the upper Campanian to the ammonites. N.F. Sohl (personal commun., Maastrichtian (®g. 5). 1971, in Minard, 1974) compiled a list of 26 molluscan species including Baculites sp., NEW OBSERVATIONS Discoscaphites sp., Sphenodiscus sp., and Eutrephoceras sp. He described Baculites sp. The exposures at Lloyd Creek consist of as common (6±25 specimens) and the other approximately2mofclayey to silty, glau- ammonite species as rare (1±5 specimens). conitic, quartz sand. A grain size analysis re- Sohl and Koch (1984: 165) subsequently as- veals that the sediments are slightly sandier sembled a faunal list of 30 molluscan species than at Brightseat, Prince Georges County. from this same site, partly reprinted in Kueh- Two-thirds (67%) of the sediments are sand, ne (1999), including 19 bivalve species, 7 approximately evenly divided between ®ne gastropod species, 1 scaphopod species, and and medium grain fractions. Quartz is the 3 cephalopod species. Kuehne (1999: 38) dominant mineral (78%), with glauconite wrote that ``The bivalves Agerostrea, Cucul- representing 7% and mica 1%. laea, and Syncyclonema are dominant. Com- Macrofossils are relatively abundant and mon subsidiaries include the bivalves Cras- occur in a mottled interval 12 cm thick. The satella, Veniella, Cubitostrea, and the am- fossils are internal molds although some pre- monite Baculites.'' serve traces of shelly iridescence. The collection (USNM, AMNH, and MAPS) consists of 32 specimens of Discoscaphites min- AGE AND CORRELATION ardi, n.sp., most of which are pieces of body Sohl and Koch (1984) interpreted the mol- chambers, although a few retain parts of luscan fauna in the Betterton quadrangle as phragmocones; 1 fragmentary specimen of representing the Haustator bilira Assem- D. iris (Conrad, 1858); 30 specimens of Bac- blage Zone, which lies above the base of the ulites vertebralis Lamarck, 1801; 1 specimen G. gansserri Subzone of Pessagno (1969). of Eubaculites latecarinatus (Brunnschweil- This interval is approximately equivalent to er, 1966); 4 fragments of Sphenodiscus pleu- the whole of the upper Maastrichtian (®gs. 4, risepta (Conrad, 1857); and 7 pieces of 5). Sphenodiscus sp., which are too broken for Hansen (1992) reported three studies speci®c identi®cation. based on a core-hole through the Severn For- We analyzed a sample of the matrix as-

← Fig. 5. Biostratigraphic position of the Severn Formation according to various authors, based on the samples shown in ®gure 4. We have interpreted the results of these studies in terms of today's biostratigraphic usage, even if they were not expressed that way originally, and may therefore have intro- duced errors into the interpretation. 12 AMERICAN MUSEUM NOVITATES NO. 3454

TABLE 1 Occurrences of Dinocyst Taxa from the Severn Formation, Marylanda

sociated with the ammonites for dino¯agel- ROUND BAY,ANNE ARUNDEL COUNTY lates (U.S. Geological Survey Paleobotanical STRATIGRAPHY AND PALEONTOLOGY no. R6235). The species (table 1, ®gs. 6, 7) notably include De¯andrea galatea (Le- The type locality of the Severn Formation jeune-Carpentier, 1942) Lentin & Williams, is on the east bank of the Severn River at 1973. The preservation is good, the diversity Round Bay, 0.64 km north of Swan Point, is high, and no single species dominates. Anne Arundel County, Maryland (Minard, 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 13

1980). The Severn Formation is 12.6 m thick Sphenodiscus sp. Owens et al. (1977: ®g. 61) and disconformably overlies the Matawan illustrated a section of presumably this same Formation and underlies the Brightseat For- site showing a bed labeled with Discosca- mation (®g. 3). Minard (1980) noted that the phites conradi and Baculites undatus near upper boundary represents a paraconformity. the middle of the formation, approximately According to Minard (1980: 10), the expo- 2.9 m above the point of exposure and 4.6 sure ``consists of dark- to medium-gray, clay- m below the top. ey and silty, poorly sorted, mostly ®ne- to Benson (1976) studied the dino¯agellates medium-grained sparsely glauconitic quartz of the Severn Formation at Round Bay on sand containing a fair amount of both very the western shore of the Severn River ap- ®ne and coarse to very coarse quartz grains proximately 2±3 km southwest of the type and granules, colorless mica, and carbona- locality, presumably the same site described ceous matter.'' Minard (1980: 12) recorded a by Sohl and Koch (1984). Based on Benson's slight increase in grain size toward the mid- stratigraphic section of this site, the Severn dle of the section, culminating in coarse to Formation is approximately 10 m thick. It is very coarse quartz grains and granules. He identical to that at the type locality, including also noted a slight decrease in the percentage the clay layer near the top of the unit, but is of glauconite upward toward the middle of missing the lower 2.5 m of the formation that the section, followed by an increase in the are exposed at the type locality. percentage toward the top. Discontinuous layers of montmorillonitic clay are common AGE AND CORRELATION in an interval approximately 30 cm thick 1 m below the top of the formation. Sohl and Koch interpreted the molluscan Minard (1980) stated that three fossilifer- fauna at Round Bay as representing the ous beds are locally present. As shown in his Haustator bilira Assemblage Zone. This is stratigraphic section, they occur at 3 m above approximately equivalent to the upper Maas- the bottom, 7 m above the bottom, and 9.6 trichtian (®g. 5). m above the bottom (ϭ 3 m below the top). Benson (1976) analyzed 16 samples from Owens et al. (1977: ®g. 61) illustrated a gen- the Severn Formation at Round Bay and de- eralized stratigraphic section from this site ®ned three informal biostratigraphic zones, showing these same three beds but at slightly A, B, C, in ascending order, based on the different levels: 3 m above the bottom, 7.5 distribution of dino¯agellates (®gs. 4, 5). m above the bottom, and 10 m above the Zone A comprises the bottom 2 m of the for- bottom (ϭ 4 m below the top). According to mation, Zone B the overlying 2.5 m, and Minard (1980: 12), the fossils ``are mostly Zone C the rest of the formation (ϳ5 m). iron-oxide coated casts and molds in the Firth (1987, text-®g. 7) interpreted Benson's clayey sand; a few outcrops contain calcar- Zone A as lower Maastrichtian and the upper eous shells.'' one-half of Zone C as upper Maastrichtian; Sohl and Koch (1984: 164) described an- he stated that the exact boundary between the other locality (location no. 400) from the up- lower and upper Maastrichtian was dif®cult per part of the Severn Formation at Round to pinpoint but lay somewhere between the Bay, Anne Arundel County. This locality is top of Zone A and the middle of Zone C. on the western shore of the Severn River ap- May (1980) studied the dino¯agellates and proximately 2±3 km southwest of the type acritarchs from the Severn Formation from locality, although the coordinates given are two sites in the Round Bay area comprising not precise enough to locate it exactly. They four samples from the upper and lower part observed a fossiliferous horizon 10 ft (3 m) of the formation (®gs. 4, 5). Based on a com- above sea level yielding internal molds in a parison with the biostratigraphic distribution matrix of dark gray ®ne sand, with glauco- of these fossils in New Jersey, he concluded nite and mica. They listed 31 specimens of that the samples, as a whole, were early Baculites (Eubaculites) carinatus, 25 speci- Maastrichtian in age, although the meaning mens of Baculites sp., 40 specimens of Dis- of this assignment in terms of today's usage coscaphites conradi var., and 3 specimens of is not entirely clear. 14 AMERICAN MUSEUM NOVITATES NO. 3454

NEW OBSERVATIONS 1834), and two specimens of Eubaculites cf. The ammonites we describe were found in E. carinatus. a drawer of Norman F. Sohl's material at the The matrix associated with USNM 525323 U.S. National Museum. The only label in the was analyzed for dino¯agellates (U.S. Geo- entire drawer was Round Bay, Maryland. logical Survey Paleobotanical no. R6374). This may represent the type locality or, more The preservation is good, the diversity is likely, the opposite shore on the banks of the moderate, and no single species dominates. Severn River approximately 2±3 km south- The ¯ora is listed in table 1 and illustrated west of the type locality. The dino¯agellates in ®gures 6 and 7 and notably includes Pa- from the matrix of one of the ammonites (see lynodinium grallator Gocht, 1970 and Thal- below) indicate that the fossils are probably assiphora pelagica (Eisenack, 1954) Eisen- from the upper part of the Severn Formation, ack & Gocht, 1960. according to the measured section given by EEDEE FORMATION Benson (1976). In all likelihood, the ammo- P nites are from the same fossiliferous horizon The Peedee Formation is a thick marine described by Sohl and Koch (1984) and sequence that crops out on the Carolina Owens et al. (1977) approximately 4 m be- Coastal Plain and is widespread in the sub- low the top of the formation. However, it is surface (Stephenson, 1923). It unconform- unclear if all of the ammonites are from this ably overlies the Donoho Creek Formation same horizon, because only one specimen and unconformably underlies deposits that was sampled for dino¯agellates. range in age from Paleocene to Holocene, The matrix consists of dark gray to black depending on the locality (Wheeler and Cur- clayey sand with pieces of lignite. The am- ran, 1974). It consists of dark greenish to monites are internal molds composed of the gray, sparingly micaceous and glauconitic, same material as the matrix itself and are muddy sand with beds of sandy limestone mostly fragments. Three small pieces of sca- (biomicrudite) near the top of the formation. phites were in a separate box. They are free Sohl and Owens (1991) interpreted the Pee- of matrix and have a pinkish-buff appear- dee Formation as having been deposited on ance, and one is stained with iron oxide. the shelf and re¯ecting at least two cycles of A grain size analysis of the matrix at- sedimentation. tached to USNM 525323 reveals that the per- Most of the Peedee Formation is late centage of sand (45%) is more similar to that Maastrichtian in age (Sohl and Owens, 1991; at Brightseat (48%) than that at Lloyd Creek Edwards et al., 1999). Sohl and Owens (67%). Most of the sand falls in the very ®ne (1991) divided the unit into three molluscan grain fraction. Quartz is the dominant min- zones, the highest of which is the Haustator eral (46%) with lesser, nearly equal percent- bilira Assemblage Zone, which, according to ages of glauconite (21%) and mica (22%). them, contains Sphenodiscus. This zone We identi®ed six specimens of Discosca- forms a band paralleling the Carolina coast phites iris (Conrad, 1858), one specimen of and includes the fossil sites yielding the am- Discoscaphites cf. D. iris, one specimen of monites we describe. Discoscaphites cf. D. minardi, n.sp., one The ammonites were collected from two specimen of Eubaculites carinatus (Morton, sites in Brunswick County, North Carolina

→ Fig. 6. Dino¯agellates from the Severn Formation, Maryland. A, B, J±L, AMNH loc. 3260 (R6370), Brightseat, Prince Georges County; C, F, I, AMNH loc. 3252 (R6235), Lloyd Creek, Kent County; D, E, G, H, U.S.G.S. Paleobot. loc. R6374, Round Bay, Anne Arundel County. A, B. De¯andrea galatea (Lejeune-Carpentier, 1942) Lentin & Williams, 1973. C. Thalassiphora pelagica (Eisenack, 1954) Ei- senack & Gocht, 1960. D, E. Palynodinium grallator Gocht, 1970. F. Palaeoperidinium sp. G, H. Disphaerogena carposphaeropsis Wetzel, 1933 (ϭ Cyclapophysis monmouthensis). I. Circulodinium distinctum (De¯andre & Cookson, 1955) Jansonius, 1986 species complex. J±L. Kleithriasphaeridium truncatum (Benson, 1976) Stover & Evitt, 1978. 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 15 16 AMERICAN MUSEUM NOVITATES NO. 3454

(®g. 1). Don Clements (Rocky Point, NC) rated ledges, one at the top of the formation collected at the Todd Marl Pit and supplied and one at approximately 1 m above maxi- most of the information about both sites. The mum low tide. The ammonite we describe Todd Marl Pit produces crushed shell marl probably comes from the lower indurated from the Plio-Pleistocene Waccamaw For- ledge. mation, which unconformably overlies the The ammonites are all internal molds Peedee Formation at this site. The pit expos- without any original shell. We identi®ed one es approximately 1.5 m of the Peedee For- phragmocone of Sphenodiscus lobatus and mation below the Waccamaw Formation. Oc- ®ve specimens of Discoscaphites gulosus, casionally, during mining operations, the en- one of which is nearly complete but very tire portion of the Waccamaw Formation was worn. Based on the presence of D. gulosus, removed, revealing the indurated, eroded up- these ammonites probably represent the D. per surface of the Peedee Formation. The conradi Zone. Peedee Formation consists of greenish, mud- A sample of part of the phragmocone of dy, very ®ne to ®ne sand with indurated nod- Sphenodiscus lobatus (AMNH 48554) was ules randomly distributed throughout the sec- analyzed for nannofossils by Jean M. Self- tion. These nodules contain masses of Exo- Trail (U.S. Geological Survey, Reston, VA). gyra, many of which are in life position. The Nannofossils are abundant with moderate to associated fauna includes species of Eutre- good preservation. There is occasional over- phoceras, Pycnodonte, Agerostrea, Cucul- growth of the nannofossils but not enough to laea, and Anomia. obscure identi®cation. The taxa are listed in The second site, collected by Ned Gilmore table 2 and notably include Lithraphidites (ANSP), is the John D. Long County Park. quadratus Bramlette and Martini, 1964. It is several kilometers from the well-known Hilton Park locality on the bluffs of the BIOSTRATIGRAPHY northeast Cape Fear River, Wilmington, New Integrating the ammonite, dino¯agellate, Hanover County, described by Stephenson and nannofossil data from these various sites (1923) and Sohl and Koch (1984), and re- helps re®ne the age of the Severn and Peedee ported to have Sphenodiscus. The County Formations and clarify the ammonite zona- Park features a large square cut (approxi- tion of the upper Maastrichtian. Our aim is mately 80 m wide at its widest point) exca- to correlate the ammonite zones in this area vated into the banks of the Brunswick River. with the established calcareous nannofossil (This and adjacent cuts were made during zonation. World War II to house liberty ships that were constructed in nearby Wilmington.) The cut AMMONITE BIOSTRATIGRAPHY exposes at maximum low tide approximately 2 m of the Peedee Formation below the Wac- The upper Maastrichtian on the Gulf and camaw Formation. The Peedee Formation Atlantic Coastal Plain has been divided into consists of muds and sands with two indu- two ammonite zones. Cobban and Kennedy

→ Fig. 7. Dino¯agellates from the Severn Formation, Maryland. D±H, J, K, M, Q, S, AMNH loc. 3260 (R6370), Brightseat, Prince Georges County; N±P, AMNH loc. 3252 (R6235), Lloyd Creek, Kent County; A±C, I, L, R, U.S.G.S. Paleobot. loc. R6374, Round Bay, Anne Arundel County. A±C. Gla- phyrocysta expansa (Corradini, 1972) Roncaglia & Corradini, 1997 (? ϭ G. perforata sensu Schiùler et al., 1997). D. Cordosphaeridium ®brospinosum Davey & Williams, 1966. E. Operculodinium/Fibrocysta complex. F, G. Isabelidinium aff. I. cooksoniae (Alberti, 1959) Lentin & Williams, 1977. H. Hafnias- phaera ¯uens Hansen, 1977. I, K. Cribroperidinium spp. misc. J. Conneximura ®mbriata May, 1980. L. Tanyosphaeridium xanthiopyxides (Wetzel, 1933) Stover & Evitt, 1978. M. Piercites pentagonum (May, 1980) Habib & Drugg, 1987. N. Spinidinium ?clavus Harland, 1973. O. Palaeocystodinium aus- tralinum (Cookson, 1965) Lentin & Williams, 1976. P. ?Andalusiella rhombohedra of Edwards et al. (1984). Q. Areoligera/Glaphyrocysta complex. R. Miscellaneous small peridinicean. S. Cyclopsiella ?sp. of Edwards et al. (1984). 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 17 18 AMERICAN MUSEUM NOVITATES NO. 3454

TABLE 2 mation in northeast Texas, the Prairie Bluff Nannofossil Taxa from the Peedee Formation, Chalk in Mississippi and Alabama, and the Todd Marl Pit, Brunswick County, North Carolina Severn Formation in Maryland. The ammo- (J. Self-Trail, personal commun., 2004) nites consist of Sphenodiscus lobatus, S. pleurisepta, Discoscaphites conradi, Discos- caphites gulosus, Jeletzkytes nebrascensis, Glyptoxoceras rugatum, Baculites vertebralis, Eubaculites carinatus, and E. latecarinatus. The D. conradi Zone is an assemblage zone and not all of its constituent species are present throughout its stratigraphic and geographic range. For example, Jeletzkytes nebrascensis is absent in the Prairie Bluff Chalk but is present in the Severn Formation. The boundaries of the D. conradi Zone were not speci®ed, but by implication, the lower boundary is the lowest occurrence of D. conradi. The upper boundary is the lowest occurrence of Discoscaphites minardi, n.sp. of the overlying D. minardi Zone. On the basis of the associated dino¯agellates, the D. conradi Zone is the lowest of the three ammonite zones described (see below). The D. conradi Zone is represented in Maryland by the ammonite fauna of the Sev- ern Formation at Oxon Hill, Randolph Vil- lage, Brightseat, Landover, and Largo, Prince Georges County, Maryland, on the western shore of Chesapeake Bay (Kennedy et al., 1997). This zone has not been recognized in other parts of Maryland although age-equivalent strata are present (see below). The D. conradi Zone occurs in the Peedee Formation in Brunswick County, North Car- olina, although the name bearer of this zone (1995) established the Discoscaphites con- has not yet been collected from this site. The radi Zone and the D. iris Zone. They placed beds contain Sphenodiscus lobatus and Dis- the D. conradi Zone above the D. iris Zone coscaphites gulosus and overlap with part or but did not regard this placement as de®ni- all of the Haustator bilira Assemblage Zone tive. (Sohl and Owens, 1991). We argue for a slightly different zonal The D. conradi Zone is not well expressed scheme based on the succession of ammo- in New Jersey, although age-equivalent strata nites and associated dino¯agellates in the are present as indicated by associated dino- Severn Formation and correlative units on ¯agellates. Sphenodiscus lobatus, Baculites the Gulf and Atlantic Coastal Plain. We rec- vertebralis, and a single specimen of Jeletz- ognize three ammonite zones (®g. 8). The kytes nebrascensis have been recovered in lowest is the D. conradi Zone, the next high- association with dino¯agellates in the upper er is the D. minardi Zone, and the highest is part of the Navesink Formation and the lower the D. iris Zone. part of the New Egypt Formation in the The D. conradi Zone was established by Crosswicks Creek Drainage in southern Cobban and Kennedy (1995) for ammonite Monmouth County. Sphenodiscus lobatus occurrences in parts of the Corsicana For- and associated dino¯agellates also occur in 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 19

Fig. 8. Proposed ammonite zonation of the upper Maastrichtian on the Gulf and Atlantic Coastal Plain and the corresponding zones in the U.S. Western Interior. The base of each zone is de®ned by the lowest occurrence of the index ammonite. The ammonite zones are correlated with the established calcareous nannofossil zonation based on the biostratigraphic distribution of the dino¯agellates and nannofossils associated with the ammonites in Maryland and North Carolina. The D. minardi Zone has not yet been recognized in the Gulf Coastal Plain. Correlation with the ammonite zones in the Western Interior is based on the presence of Discoscaphites conradi and Isabelidinium cooksoniae. the middle of the Tinton Formation in north- kota (Landman and Waage, 1993), where it eastern Monmouth County, but no scaphites is associated with J. nebrascensis, Hoplos- have been recovered from this site. caphites comprimus (Owen, 1852), D. gulo- The D. conradi Zone on the Gulf and At- sus, Discoscaphites rossi Landman and Waa- lantic Coastal Plain corresponds, in part, to ge, 1993, S. lobatus, and rare specimens of the combined zones of Hoploscaphites ni- T. columna and Baculites larsoni Cobban colletii and Jeletzkytes nebrascensis in the and Kennedy, 1992. The underlying Hoplos- Western Interior (®g. 8). Discoscaphites con- caphites birkelundae Zone lacks any species radi is present in the H. nicolletii Zone in the of Discoscaphites and is older than the D. Fox Hills Formation, South Dakota, where it conradi Zone (Landman and Cobban, 2003). is associated with H. nicolletii, Discoscaphi- Landman and Waage (1993) assigned the tes gulosus, Jeletzkytes spedeni Landman and H. nicolletii and J. nebrascensis Zones to the Waage, 1993, Trachybaculites columna lower part of the upper Maastrichtian on the (Morton, 1834), and Sphenodiscus lobatus. basis of the biostratigraphic distribution of Discoscaphites conradi is also present, al- inoceramid bivalves and Discoscaphites in though not common, in the J. nebrascensis comparison with the distribution of these fos- Zone in the Fox Hills Formation, South Da- sils in the Gulf Coastal Plain and northwest 20 AMERICAN MUSEUM NOVITATES NO. 3454

Europe. Palamarczuk et al. (2003) reached a sp., with rare specimens of Eubaculites la- similar conclusion based on an analysis of tecarinatus and Discoscaphites iris. The low- dino¯agellates from approximately the same er boundary of this zone is de®ned by the stratigraphic interval in southwestern South lowest occurrence of D. minardi, n.sp., and Dakota (see below). the upper boundary is de®ned by the lowest Landman and Waage (1993: 212, 230) not- occurrence of abundant D. iris of the over- ed minor morphological differences between lying D. iris Zone. The position of the D. populations of D. conradi and D. gulosus minardi Zone above the D. conradi Zone and from the Corsicana Formation, the Prairie below the D. iris Zone is based on strati- Bluff Chalk, and the Severn Formation ver- graphic superposition and associated dino¯a- sus those from the Fox Hills Formation. gellates (see below). Specimens from the Gulf and Atlantic Coast- The D. minardi Zone has not been rec- al Plain commonly include more highly or- ognized elsewhere in Maryland although namented forms with a midventral row of tu- age-equivalent strata are present at Round bercles compared to those in the Western In- Bay (see below). The D. minardi Zone is terior (e.g., contrast specimens of D. gulosus present at AMNH loc. 3346 near Eatontown, from the Severn Formation [Kennedy et al., northeastern Monmouth County, New Jersey, 1997: ®gs. 20K, O, 21D, E] with those from at the top of the New Egypt Formation ap- the Fox Hills Formation [Landman and Waa- proximately 1.5±2 m below the base of the ge, 1993: ®gs. 167±172]). These differences overlying D. iris Zone. The D. minardi Zone may re¯ect ecophenotypic variation related may also occur in the upper part of the Cor- to differences in temperature, depth, sub- sicana Formation, Texas, where specimens strate, and predation intensity. However, it is similar to D. minardi, n.sp. have been re- equally possible that the beds in these two ported (Kennedy and Cobban, 1993), but the areas are not exactly equivalent in age. Be- stratigraphic position of these ammonites is cause specimens of D. gulosus with a mid- not well enough constrained to adequately ventral row of tubercles are present, although demonstrate this at present. rare, in the J. nebrascensis Zone, whereas The highest ammonite zone is the Discos- they are absent altogether in the underlying caphites iris Zone. Cobban and Kennedy H. nicolletii Zone, Landman and Waage (1995) de®ned the D. iris Zone based on oc- (1993) speculated that the more highly or- currences of this species and associated am- namented form of D. gulosus is younger, thus monites on the Gulf Coastal Plain in the up- implying that the populations of D. gulosus per part of the Owl Creek Formation (and as and D. conradi on the Gulf and Atlantic reworked fossils in the basal Clayton For- Coastal Plain, which include a greater pro- mation) in Mississippi, Tennessee, and Mis- portion of highly ornamented forms, are souri (Stephenson, 1955; Sohl, 1960, 1964; slightly younger than those in the Western Kennedy and Cobban, 2000). The fauna con- Interior. sists of D. iris, D. sphaeroidalis Kennedy The Gulf and Atlantic Coastal Plain also and Cobban, 2000, D. cf. D. conradi, Bac- share few ammonite species in common with ulites cf. B. claviformis Stephenson, 1941, B. the Western Interior, further suggesting, by cf. B. undatus Stephenson, 1941, and Sphen- negative evidence, that the beds are not ex- odiscus pleurisepta. Elsewhere on the Gulf actly equivalent in age in these two areas. Coast, this zone occurs in the upper part of Curiously, Jeletzkytes nebrascensis is absent the Corsicana Formation (and as reworked in the D. conradi Zone in Mississippi and fossils in the basal Kincaid Formation) on the Alabama but is present in this zone in Mary- Brazos River, Falls County, Texas (Kennedy land and New Jersey. et al., 2001), where it contains Pachydiscus The ammonite occurrences at Lloyd Creek (Pachydiscus) jacquoti jacquoti Seunes, de®ne a new zone called the D. minardi Zone 1890, D. sphaeroidalis, D. cf. D. gulosus, after the most abundant species. The D. min- Eubaculites carinatus, and Glyptoxoceras cf. ardi Zone is an assemblage zone dominated G. rugatum. by D. minardi, n.sp., Baculites vertebralis, Cobban and Kennedy (1995) de®ned this Sphenodiscus pleurisepta, and Sphenodiscus zone as an assemblage zone, and not all of 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 21 its constituent species are present throughout South Carolina, includes the Maastrichtian the stratigraphic and geographic range of the Peedee Formation and contains nannofossils, zone. They did not specify the boundaries of foraminifera, and dino¯agellates (Edwards et the zone, but, by implication, the lower al., 1999). The core is also calibrated with boundary is the lowest occurrence of abun- strontium isotope- and magnetostratigraphy. dant D. iris and the upper boundary is the Because this core is located on the Atlantic highest occurrence of D. iris, coinciding with Coastal Plain, it provides an excellent means the Cretaceous/Tertiary boundary. of correlating the dino¯agellates in the The D. iris Zone is present at Round Bay, Maryland samples with the standard calcar- Anne Arundel County, where it consists of eous nannofossil zonation. Furthermore, by Discoscaphites iris, D. cf. D. iris, D. cf. D. regressing the age-calibrated paleomagnetic minardi, n.sp., Eubaculites carinatus, and E. data and the ranges of calcareous nannofos- cf. E. carinatus. The D. iris Zone is also pre- sils against depth in the SCR core, Edwards sent in New Jersey (Landman et al., in prep. et al. (1999, ®g. 11) calculated numerical a) where it contains Pachydiscus (Neodes- ages for key dino¯agellate datums. moceras) mokotibensis Collignon, 1952, D. The occurrences of key dino¯agellate spe- iris, D. gulosus, E. carinatus, E. latecarina- cies in the SCR core are listed below (Ed- tus, Sphenodiscus pleurisepta, and S. loba- wards et al., 1999, ®g. 5): tus. It occurs in the top of the New Egypt Lowest occurrence of Palynodinium grallator Formation (and as reworked fossils at the (370.3 ft in SCR core) base of the Hornerstown Formation) near Ea- Lowest occurrence of Disphaerogena carpos- tontown, northeastern Monmouth County phaeropsis (389.3 ft in SCR core) (Landman et al., in prep. a), near New Egypt, Lowest occurrence of Thalassiphora pelagica southwestern Monmouth County (Landman (390.8 ft in SCR core) et al., in prep. c), and near Sewell, Gloucester Highest occurrence of Isabelidinium cooksoniae County (Kennedy and Cobban, 1996), and in (436.4 ft in SCR core) the top of the Tinton Formation (and as re- Lowest occurrence of De¯andrea galatea (436.4 worked fossils at the base of the Horners- ft in SCR core) town Formation), near Freehold, central Highest occurrence of Alterbidinium acutulum (474.2 ft in SCR core) Monmouth County (Landman et al., in prep. b). As noted by Edwards et al. (1999), there The D. iris Zone occurs at and just below are several caveats to consider when using the Cretaceous/Tertiary boundary and is thus the SCR core for precise correlations. First, the youngest ammonite zone in North Amer- although the base of the Peedee Formation ica. Stratigraphic superposition and the as- in the SCR core lies in Subzone CC25b, the sociated species of dino¯agellates (see be- exact position of the base within this subzone low) indicate that this zone occurs above the is unknown. Second, calcareous nannofossil D. minardi Zone. The D. iris Zone is wide- Subzones CC25b, CC26a, and CC26b are spread and extends from Texas, Mississippi, recognized in the SCR core, but Subzone Tennessee, and Missouri on the Gulf Coastal CC25c is not. Micula murus, which else- Plain to Maryland and New Jersey on the where de®nes the base of Subzone CC25c, Atlantic Coastal Plain. ®rst appears in the SCR core within Subzone CC26a, indicating a delayed occurrence. DINOFLAGELLATE BIOSTRATIGRAPHY However, the interpretation of the paleomagnetic data in the core by Edwards et al. All of the samples from Maryland contain (1999) suggests that the chronozone of Sub- dino¯agellates, but calcareous nannofossils zone CC25c is present. Third, Subzone are absent. To evaluate the dino¯agellate oc- CC26a may be truncated in the SCR core currences in these samples, we relied on the because Lithraphidites kennethii, which oc- biostratigraphic zonation established by Firth curs elsewhere midway in Subzone CC26a, (1987) and Edwards et al. (1999) on the At- occurs near the base of this subzone in the lantic Coastal Plain. The Santee Coastal Re- SCR core; alternatively, L. kennethii may serve (SCR) core from Charleston County, have a longer range than previously reported. 22 AMERICAN MUSEUM NOVITATES NO. 3454

Fig. 9. Approximate correlation of the samples from Maryland with the Santee Coastal Reserve (SCR) core (Edwards et al., 1999). The horizontal arrows indicate sample locations in the SCR core. Because calcareous nannofossil Subzone CC25c is missing in the SCR core, Zone CC25 is shown as undifferentiated. The time scale is based on Berggren et al. (1995) as interpreted for the SCR core by Edwards et al. (1999).

Finally, it is dif®cult to determine if Subzone (R6374) near Brightseat, Prince Georges CC26b is complete, but based on paleomag- County, Maryland, include De¯andrea gal- netic and lithologic data, there is probably a atea and Isabelidinium aff. I. cooksoniae (®g. small hiatus (ca. 100,000 years) at the top of 9). By comparison with the reported occur- this subzone. The absence of Plummerita rences of these species in the Santee Coastal hantkeninoides from the top of the Creta- Reserve core, this sample represents the low- ceous also suggests that the uppermost Maas- er part of the upper Maastrichtian. It is ap- trictian is absent in the SCR core. proximately correlative with material from The dino¯agellates at AMNH loc. 3260 436.4 ft in the SCR core, which coincides 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 23 with calcareous nannofossil Subzone CC25b which is present in the Lloyd Creek sample, (Edwards et al., 1999). However, the precise was not reported by Benson (1976) at Round position within this subzone is unknown. The Bay, which is surprising given how distinc- base of the Peedee Formation in the SCR tive and well known this species is. core contains Alterbidinium acutulum, which The dino¯agellates at Round Bay, Anne is absent in the Brightseat sample, thus im- Arundel County (R6374), include Palynodi- plying, by negative evidence, that this sam- nium grallator and questionable specimens ple is slightly younger than the base of the of Thalassiphora pelagica (®g. 9). These Peedee Formation in the SCR core. By com- species represent the uppermost Maastrich- parison with the SCR core, the Brightseat tian Palynodinium grallator Zone, probably sample is 68.2±67.4 MaBP. the Tpe (T. pelagica) Subzone of Schiùler Benson (1976), as quoted in Firth (1987: and Wilson (1993) correlative with the upper text-®g. 7), reported Isabelidinium cookson- part of calcareous nannofossil Subzone iae in his Zones A and B, comprising the CC26b (65.6±65.0 Ma). Benson (personal lower 4.5 m of the Severn Formation at commun. in Firth: 1987: text-®g. 7) reported Round Bay, Anne Arundel County. The P. grallator in the upper part of his Zone C highest occurrence of this species is in his in the upper 2 m of the Severn Formation at Zone B. Palamarczuk et al. (2003) also re- Round Bay, presumably from approximately ported I. cooksoniae as well as Cordosphaer- the same interval that we sampled. idium ®brospinosum from their sample from the Fox Hills Formation in South Dakota. NANNOFOSSIL BIOSTRATIGRAPHY The dino¯agellates at AMNH loc. 3252 The nannofossils from the Peedee For- (R6235), Lloyd Creek, Kent County, include mation from Brunswick County, North Car- De¯andrea galatea and Thalassiphora pe- olina, include Lithraphidites quadratus, in- lagica (®g. 9). However, Disphaerogena car- dicating nannofossil Subzone CC25b (J.M. posphaeropsis Wetzel, 1933 and Palynodi- Self-Trail, personal commun., 2004) (table nium grallator are absent, suggesting that 2). Furthermore, no species indicative of the this sample is upper, but not uppermost, overlying Zone CC26 are present (e.g., Cer- Maastrichtian. It is approximately correlative atolithoides kamptneri or Micula prinsii). with material from 390.8 ft in the SCR core, which lies within the Nephrolithus frequens BIOSTRATIGRAPHIC SYNTHESIS calcareous nannofossil Zone encompassing the upper part of Subzone CC26a and the The dino¯agellates and nannofossils as- lower part of Subzone CC26b (Edwards et sociated with the ammonites permit an ap- al., 1999), according to the calcareous nan- proximate correlation of the ammonite zones nofossil zonation of Perch-Nielsen (1985). with the standard calcareous nannofossil zo- By comparison with the SCR core, the Lloyd nation. The D. minardi Zone and the D. iris Creek sample is 66.4±66.0 MaBP. Zone are each represented by a single dino- This interval correlates with the lower part ¯agellate sample from Maryland, while the of Zone C of Benson (1976) in the middle D. conradi Zone is represented by a dino¯a- of the Severn Formation at Round Bay. It is gellate sample from Maryland and a nanno- above the highest occurrence of Isabelidi- fossil sample from North Carolina, both of nium cooksoniae at the top of his Zone B and which yielded the same age. We regard the below the lowest occurrence of Disphaero- sample from each ammonite zone as marking gena carposphaeropsis (ϭ Cyclapophysis the base of that particular zone. monmouthensis) near the middle of his Zone The biostratigraphic distribution of dino- C. The Lloyd Creek sample also contains the ¯agellates and nannofossils supports the pro- Circalodinium distinctum (De¯andre & posed ammonite zonation indicating, in as- Cookson, 1955) Jansonius, 1986 species cending stratigraphic order, the Discoscaphi- complex equivalent to Benson's Cyclone- tes conradi Zone, the D. minardi Zone, and phelium distinctum, which ranges from the the D. iris Zone (®g. 8). The base of the D. middle of his Zone B to the lower part of his conradi Zone approximately correlates with Zone C. However, Thalassiphora pelagica, Subzone CC25b although its precise position 24 AMERICAN MUSEUM NOVITATES NO. 3454 is indeterminate. The base of the D. minardi by Kennedy et al. (1997), Sohl and Koch Zone approximately correlates with the Sub- (1984), Smith (personal commun., 1976, in zone CC26a/b boundary but may range from Brouwers and Hazel, 1978), and May (per- the very uppermost part of Subzone CC26a sonal commun., 1976, in Brouwers and Ha- to the lowermost part of Subzone CC26b. zel, 1978) (®g. 5). This assignment is also The base of the D. iris Zone approximately consistent with that of Brouwers and Hazel correlates with the upper part of calcareous (1978), even though their conclusions were nannofossil Subzone CC26b. based on samples from the entire thickness The inferred ages of the D. conradi Zone of the formation in this area. Beds of this age in Maryland and North Carolina and the D. occur in the lower part of the Severn For- iris Zone in Maryland are compatible with mation at Round Bay, based on the dino¯a- the published ages of the formations in which gellate biostratigraphy of Benson (1976) and these zones occur elsewhere on the Gulf and Firth (1987). Atlantic Coastal Plain. The D. conradi Zone The lower part of the upper one-third of occurs in parts of the Prairie Bluff Chalk in the Severn Formation at Lloyd Creek repre- Alabama and Mississippi, as well as in the sents the middle part of the upper Maastrich- Corsicana Formation in northeast Texas. The tian, corresponding to the top of calcareous D. iris Zone occurs in the Owl Creek For- nannofossil Subzone CC26a and the bottom mation in Mississippi, Tennessee, and Mis- of Subzone CC26b (®g. 5). This falls within souri, in the upper part of the Coriscana For- the range inferred by Minard (1980) and mation in Falls County, Texas, and in the Sohl and Koch (1984) for the same strati- New Egypt Formation in New Jersey. All of graphic interval, as well as that inferred by these formations span the upper Maastrich- Olsson (1992), Brennen (1992), and Gohn tian and include the estimated ranges of both (1992), even though their conclusions were ammonite zones (for the age of the Corsicana based on samples from the top and bottom Formation, see Kennedy and Cobban [1993] of the formation at another, nearby locality. and Kennedy et al. [2001]; for the Prairie Age-equivalent strata occur in the lower part Bluff Chalk, see Smith and Mancini [1982] of the upper one-third of the Severn Forma- and Olsson et al. [1996]; for the Owl Creek tion at Round Bay, based on the dino¯agel- Formation, see Stephenson [1955], Russell late biostratigraphy of Benson (1976) and [1975], Smith and Mancini [1982], Kennedy Firth (1987). and Cobban [2000], and Kennedy et al. The upper part of the Severn Formation at [2001]; and for the New Egypt Formation, Round Bay represents the upper part of cal- see Landman et al. [in prep. a, c]). careous nannofossil Subzone CC26b. This interpretation is consistent with that of Ben- AGE AND CORRELATION OF THE SEVERN son (1976) and Firth (1987) and falls within FORMATION the range of Sohl and Koch (1984), all of whose samples are from the same strati- Our conclusions about the age and corre- graphic interval. It differs from that of May lation of the Severn Formation are consistent (1980) whose conclusions were based on with previously published interpretations of samples from the same and nearby sites (®g. the age of this unit and indicate that the am- 5). monite-bearing beds were deposited during Our results suggest that the upper part of the late Maastrichtian (®g. 5). Furthermore, the Severn Formation encompassing at least based on age and stratigraphic relationships, the upper two ammonite zones is missing erosion must have removed some of the for- from Prince Georges County. This interval mation in the southwestern part of its distri- must have been removed by erosion at the bution. end of the Cretaceous or beginning of the The upper part of the Severn Formation in Paleocene. This interpretation is consistent Prince Georges County represents the lower with isopach maps showing a thinning and part of the upper Maastrichtian, correspond- rapid pinching out of the Severn Formation ing to calcareous nannofossil Subzone without any change in lithofacies in the west- CC25b. This falls within the range inferred ern part of Prince Georges County (Glaser, 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 25

1968), implying that the Severn Formation Western Interior but were present in the Gulf originally covered a much broader area and and Atlantic Coast, in addition to Europe, was subsequently removed by erosion. Asia, and Africa. After the disappearance of the Western Interior Seaway or at least a con- AMMONITE DIVERSITY AND BIOGEOGRAPHY nection between it and the Gulf and Atlantic Coast in the middle late Maastrichtian, am- The presence of three ammonite zones in monite species were either endemic to the parts of the Gulf and Atlantic Coastal Plain Gulf and Atlantic Coast or were cosmopoli- indicates a succession of ammonite commu- tan. During D. minardi Zone time, B. verte- nities that lived along the late Maastrichtian bralis, Eubaculites latecarinatus, and E. car- coastline. However, there is no indication inatus were cosmopolitan while during D. that these communities were persistent over iris Zone time, E. latecarinatus, E. carinatus, time. In contrast, the stratigraphic record Pachydiscus (Neodesmoceras) mokotibensis, suggests that these communities were inter- and P.(P.) jacquoti jacquoti were cosmo- mittent, although the vagaries of taphonomy politan. always complicate any interpretation. To assess the change in ammonite diver- CONVENTIONS sity over time, we counted up the number of species in each zone. We included all the The ammonites described in this paper are species in a zone even if they did not occur reposited in the Academy of Natural Scienc- everywhere in that zone (e.g., we included es of Philadelphia (ANSP), the American Jeletzkytes nebrascensis in the D. conradi Museum of Natural History (AMNH), the Zone even though it does not occur in the Monmouth Amateur Paleontologist's Society Prairie Bluff Chalk). We did not include (MAPS), West Long Branch, New Jersey, questionable species referred to as ``cf.'' or and the U.S. National Museum (USNM). Di- ``sp.'' The number of ammonite species over mensions of specimens are expressed in mil- time does not vary signi®cantly. There are limeters. Arrows on photographs indicate the nine species in the D. conradi Zone, ®ve in base of the body chamber, where visible. All the D. minardi Zone, and eight in the D. iris specimens were photographed in the conven- Zone, implying no monotonic decrease in di- tional manner (with the aperture on top) ex- versity toward the close of the Cretaceous. cept for scaphites and sphenodiscids, which The youngest zone, the D. iris Zone, is very are oriented with the aperture on the bottom, fossiliferous, especially in Mississippi, Ten- approximating their position in life. Suture nessee, Missouri, and New Jersey. Recently terminology is that of Wedekind (1916), as discovered exposures in the Manasquan Ba- reviewed by Kullmann and Wiedmann sin near Freehold, central Monmouth Coun- (1970). The term ``rib index'' as applied to ty, New Jersey, are especially rich in am- baculites is the number of ribs in a distance monites and other molluscs (Landman et al., equal to the whorl height at the midpoint of in prep. b). These occurrences indicate a the interval over which the ribs were count- thriving community immediately prior to the ed. The value of the rib index can be an in- extinction of the ammonites at the end of the teger or a fraction, although a fractional part Cretaceous. of a rib does not make any sense from a prac- The fauna in all three ammonite zones tical point of view. shows a similar biogeographic pattern in- In discoscaphites with multiple rows of tu- volving a mix of endemic and cosmopolitan bercles, we report the distance between tu- species. In the early part of the late Maas- bercle rows at midshaft. The distance is also trichtian, Discoscaphites conradi, D. gulo- given, if possible, between outer ventrolat- sus, Jeletzkytes nebrascensis, and Sphenodis- eral tubercles on either side of the venter. cus lobatus were widely distributed in the These measurements involve several approx- Western Interior as well as in parts of the imations: (1) the measurements are taken Gulf and Atlantic Coast. The two species of from the tips of the tubercles or, if the tu- diplomoceratids, Baculites vertebralis and bercles are elongate, from midway on the Glyptoxoceras rugatum, were absent in the swellings; (2) the measurements do not take 26 AMERICAN MUSEUM NOVITATES NO. 3454 into account the curvature of the ¯anks AMNH 49412, 49417, 49420, and 49421 (sometimes the tubercles occur on an in¯ated from AMNH loc. 3252 from the Severn For- surface, sometimes on a ¯at surface); and (3) mation, Kent County, Maryland. the measurements are taken to the nearest DESCRIPTION: AMNH 49412 is a fragment 0.25 mm. of a phragmocone slightly more than one- half whorl long (®g. 10A±C). It is missing SYSTEMATIC PALEONTOLOGY most of its venter on the adoral one-third CLASS CEPHALOPODA whorl. The whorl width and height at the adapical end of the specimen are 7.8 mm and ORDER AMMONOIDEA VON ZITTEL, 1884 25.7 mm, respectively; the ratio of whorl SUBORDER AMMONITINA HYATT, 1889 width to height is 0.30. The umbilicus is SUPERFAMILY ACANTHOCERATACEAE DE small but obscured by matrix. The whorl sec- GROSSOUVRE, 1894 tion is oxyconic. The inner ¯anks are slightly concave, the mid¯anks are broadly rounded, FAMILY SPHENODISCIDAE HYATT, 1900 and the outer ¯anks gently slope to an acute Genus Sphenodiscus Meek, 1871 venter. The ornament on the left side is better preserved. There are four radial swellings on TYPE SPECIES: Ammonites lenticularis Owen, 1852: 579 (non Young and Bird, the outer ¯anks, which become more widely 1828: 269, ®g. 5), by original designation, ϭ spaced adorally. The distance between the Ammonites lobata Tuomey, 1856: 168. two most adoral swellings is 8 mm. It is possible that there are two swellings on the mid- Sphenodiscus pleurisepta (Conrad, 1857) ¯anks but the specimen is not well enough Figures 10A±J preserved to determine this. The suture has narrow-stemmed saddles with phylloidlike Ammonites pleurisepta Conrad, 1857: 159, pl. 15, terminations (®g. 11). ®g. 1. There are three other specimens. AMNH Sphenodiscus lenticularis (Owen). Kellum, 1962: 49421 is a small fragment of a phragmocone 68, pl. 4, ®gs. 3, 4; pl. 5, ®g. 1; pl. 6, ®gs. 1, 2. Sphenodiscus pleurisepta (Conrad, 1857). Cobban consisting of part of the outer ¯anks and and Kennedy, 1995: 12, ®g. 8.5 (with full syn- acute venter (®g. 10F±H). Two radial swell- onymy). ings are present on the outer ¯anks with a Sphenodiscus pleurisepta (Conrad, 1857). Ken- distance of approximately 9 mm between nedy et al., 1996: 11, ®gs. 4A, 5±12. them. AMNH 49420 is a worn piece of a Sphenodiscus pleurisepta (Conrad, 1857). Ken- phragmocone with a maximum preserved nedy et al., 1997: 9, ®gs. 9J, 11±14. whorl height of 41.6 mm (®g. 10D, E). It Sphenodiscus pleurisepta. Larson et al., 1997: 91. shows faint swellings on the inner and mid- Sphenodiscus pleurisepta (Conrad, 1857). Land- dle ¯anks. AMNH 49417 is a small piece of man and Cobban, 2003: 17, ®gs. 12±15. a body chamber with an acute venter and TYPE: The holotype is USNM 9888, said weak swellings on the outer ¯anks (®g. 10I, to be from ``Jacun, 3 miles below Laredo'', J). but probably from the Escondido Formation DISCUSSION: Although fragmentary, these of the Rio Grande Region, probably in Mav- specimens all show swellings on the outer erick County, Texas (Stephenson, 1941, ¯anks and, in a couple of instances, on the 1955). mid¯anks as well. This suggests that these MATERIAL: There are four specimens: specimens are Sphenodiscus pleurisepta rath-

→ Fig. 10. A±J. Sphenodiscus pleurisepta (Conrad, 1857), AMNH loc. 3252, Severn Formation, Kent County, Maryland. A±C. AMNH 49412. A, Right lateral; B, ventral; C, left lateral. D, E. AMNH 49420. D, Apertural; E, left lateral. F±H. AMNH 49421. F, Right lateral; G, ventral; H, left lateral. I, J. AMNH 49417. I, Lateral; J, ventral. K±O. Sphenodiscus sp., same locality as A±J. K. AMNH 49419, left lateral. L, M. AMNH 49415. L, Lateral; M, ventral. N, O. AMNH 49416. N, Ventral; O, lateral. All ®gures ϫ1. 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 27 28 AMERICAN MUSEUM NOVITATES NO. 3454

Fig. 11. Composite suture of Sphenodiscus pleurisepta (Conrad, 1857) at a whorl height of approximately 27 mm, AMNH 49412, AMNH loc. 3252, Severn Formation, Kent County, Maryland. er than Sphenodiscus lobatus (Tuomey, per part of the Pierre Shale and Fox Hills 1856). Cobban and Kennedy (1995) dis- Formation in Weld County, Colorado (Ken- cussed the synonymy of S. pleurisepta and nedy et al., 1996; Landman and Cobban, its differences from congeneric species. Be- 2003). cause this species has an unusually long range (the entire upper Maastrichtian), it is Sphenodiscus lobatus (Tuomey, 1856) probably worthwhile in the future to more Figure 12A, B closely examine specimens of this species Ammonites lenticularis Owen, 1852: 579, pl. 8, from the Gulf and Atlantic Coastal Plain and ®g. 5. those from the Western Interior to con®rm Ammonites lobatus Tuomey, 1856: 168. that they are all conspeci®c (N.L. Larson, Sphenodiscus lobatus (Tuomey, 1856). Cobban personal commun., 2004). and Kennedy,1995: 12, ®gs. 6.2, 6.3, 8.4, 8.6± OCCURRENCE: Severn Formation, Kent 8.11, 12.18, 12.19, 16.16, 16.17 (with full syn- County, Maryland; Severn Formation, Prince onymy). Georges County, Maryland (Kennedy et al., Sphenodiscus lobatus (Tuomey, 1856). Kennedy 1997). This species occurs in New Jersey in and Cobban, 1996: 802, ®g. 2.4±2.6, 2.13, 2.14, the top of the New Egypt Formation and as 2.19±2.21. reworked material in the base of the Hor- Sphenodiscus lobatus (Tuomey, 1856). Kennedy et al., 1997: 4, ®gs. 3±8, 9A±I, 10. nerstown Formation, northeastern Monmouth County, and in the upper part of the New TYPE: The holotype, from Noxubee Coun- Egypt Formation, southwestern Monmouth ty, Mississippi, is lost (®de Stephenson, County (Landman et al., in prep. a, c). It is 1941: 434). known on the Gulf Coastal Plain from the MATERIAL: There is one specimen (AMNH Corsicana Formation in northeastern Texas 48554) from the Peedee Formation, Bruns- (Kennedy and Cobban, 1993), the Owl Creek wick County, North Carolina. Formation in Missouri, Mississippi, and Ten- DESCRIPTION: AMNH 48554 is an internal nessee (Kennedy and Cobban, 2000), and the mold 81.6 mm in diameter (®g. 12A, B). It Prairie Bluff Chalk in Mississippi (Cobban is part of the phragmocone of a much larger and Kennedy, 1995). It is also known from specimen. A portion of the ventrolateral sur- the Escondido Formation in Trans-Pecos face on the right side is covered by a bryo- Texas and northern Mexico (Stephenson, zoan colony. There are two large circular de- 1941, 1955). In the Western Interior, this spe- pressions near the adoral end. The whorl sec- cies is reported from the Hoploscaphites bir- tion is oxyconic; the whorl width and height kelundae Zone of the Pierre Shale in Meade near the aperture are 14.9 and 47.2 mm, re- and Pennington Counties, South Dakota spectively; the ratio of whorl width to height (Kennedy et al., 1996; Larson et al., 1997), is 0.32. The umbilicus is small and bordered the Fox Hills Formation in Niobrara County, on the right side by the umbilical wall of the Wyoming (Kennedy et al., 1996), and the up- next whorl, most of which is missing. The 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 29 inner ¯anks are slightly concave, the mid- piece of the venter of a body chamber 45.5 ¯anks are broadly convex, and the outer mm long. ¯anks are nearly ¯at and converge to an DISCUSSION: These specimens are too frag- acute venter. The surface of the shell is mentary for speci®c identi®cation. However, smooth without any trace of ornament. they do not show any evidence of tubercles, OCCURRENCE: Peedee Formation, Bruns- suggesting kinship with Sphenodiscus loba- wick County, North Carolina; Tinton For- tus. mation, near Tinton Falls, northeastern Mon- OCCURRENCE: Severn Formation, Kent mouth County, New Jersey (Gallagher, County, Maryland. 1993); Tinton Formation, near Freehold, central Monmouth County, New Jersey (Land- SUBORDER ANCYLOCERATINA WIEDMANN, man et al., in prep. b); upper part of the Na- 1966 vesink Formation and lower part of the New SUPERFAMILY TURRILITACEAE GILL, 1871 Egypt Formation, southwestern Monmouth FAMILY BACULITIDAE GILL, 1871 County, New Jersey (Landman et al., in prep. c); base of the Hornerstown Formation, Genus Baculites Lamarck, 1799 Gloucester County, New Jersey (Gallagher, TYPE SPECIES: Baculites vertebralis La- 1993; Kennedy et al., 1995; Kennedy and marck, 1801: 103, by subsequent designation Cobban, 1996); Severn Formation, Prince by Meek, 1876: 391. Georges County, Maryland (Kennedy et al., 1997); Corsicana Formation, northeast Texas Baculites vertebralis Lamarck, 1801 (Kennedy and Cobban, 1993); upper part of Figures 13A±Z, a±f, 14A the Ripley Formation, Mississippi; Prairie Bluff Chalk, Alabama, and Mississippi (Cob- Baculites vertebralis Lamarck, 1801: 103. ban and Kennedy, 1995); and Providence Baculites vertebralis Lamarck, 1801. Kennedy, Sand, Chattahoochee River area, Alabama 1986: 57, pl. 11, ®gs. 6±11; pl. 12, ®gs. 1±6; and Georgia. This species is also known text-®gs. 3a±d, 7d±f, 8 (with synonymy). Baculites vertebralis Lamarck, 1801. Kennedy, in from the Escondido Formation in Trans-Pe- Kennedy et al., 1986: 1012, pl. 1, ®gs. 8, 9. cos Texas and northern Mexico. In the West- Baculites vertebralis Lamarck, 1801. Kennedy, ern Interior, it occurs in the Hoploscaphites 1987: 187, pl. 19, ®gs. 1±4, 7±10; pl. 20, ®gs. nicolletii and Jeletzkytes nebrascensis Zones 3±5; pl. 28, ®gs. 2, 7±10, 14±16; pl. 29, ®gs. of the Fox Hills Formation in north-central 1±5; pl. 30, ®gs. 1±9; text-®gs. 11a, b, 12 (with South Dakota (Landman and Waage, 1993) full synonymy). and in the J. nebrascensis Zone of the Pierre Baculites vertebralis Lamarck, 1801. Kennedy et Shale in southeastern South Dakota and al., 1997: 18, ®gs. 15E±J, M±O, 16A±F, I±K, northeastern Nebraska (Kennedy et al., 17, 18. 1998). Baculites vertebralis Lamarck, 1801. Klinger and Kennedy, 2001: 215, ®gs. 160, 161. Sphenodiscus sp. TYPE: Lectotype, by the subsequent des- Figure 10K±O ignation of Kennedy (1986: 57), is the original of Faujas-Saint-Fond (1799: pl. 21, ®gs. MATERIAL: There are seven specimens: 2, 3). AMNH 49413, 49415, 49416, 49418, 49419, MATERIAL: There are 30 specimens, mostly and 50757, and USNM 522937 from AMNH fragments of body chambers, all of which are loc. 3252 from the Severn Formation, Kent internal molds, from AMNH loc. 3252, the County, Maryland. Severn Formation, Kent County, Maryland: DESCRIPTION: AMNH 49415 and 49416 are MAPS A2035c1±3, AMNH 47427, 49400, ventral pieces of body chambers (®g. 10L± 49401, 49403±49405, 49408±49411, 49427, O). The outer ¯anks converge to a relatively 49428, 50543, and 50683±50690, and acute venter. There are no swellings on the USNM 522939±522944. ¯anks. AMNH 49413, 49418, and 49419 are DESCRIPTION: The collection consists of ro- worn pieces of large phragmocones (®g. bust and slender specimens, which may rep- 10K). USNM 522937 (not illustrated) is a resent macroconchs and microconchs, re- 30 AMERICAN MUSEUM NOVITATES NO. 3454 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 31 spectively. However, this is dif®cult to de- based on the distance between two consec- termine because the stage of ontogeny of utive ribs. The ¯anks are covered with broad each specimen is unknown (no evidence of crescentic ribs with a rib index of approxi- septal approximation or apertural modi®ca- mately 7 based on the average distance be- tion indicative of maturity). There are three tween three consecutive ribs. The ribs project robust specimens: MAPS A2035c1, 2, and strongly forward on the outer third of the AMNH 47428. ¯anks and intersect the line of the venter at MAPS A2035c1 is a fragment of a body an angle of 39Њ. Very faint ribs are visible on chamber 46.7 mm long with a taper angle of the venter on the adapical end of the speci- 5.0Њ (®g. 13Q±T). The whorl section is com- men. pressed ovoid with maximum whorl width at AMNH 47428 is a small fragment of a midwhorl height; the ratio of whorl width to body chamber 37.0 mm long (®g. 13I±L). It height near the adoral end is 0.62. The dor- is slightly crushed and worn on the venter. sum is broadly rounded although it appears The whorl section is compressed ovoid with slightly angular due to crushing and wear on a ratio of whorl width to height of 0.63 at the dorsal half of the ¯anks on the left side. the adoral end. The dorsum is very broadly The ¯anks are broadly rounded and gently rounded with a fairly abruptly rounded dor- converge to an abruptly rounded ventrolat- solateral shoulder. The ¯anks are nearly ¯at eral shoulder and a narrow, broadly rounded and gently converge to a narrow, broadly venter. Ribs are absent on the dorsum but rounded venter. Ribs cross the dorsum with slant gently backward on the dorsal third of a weak convexity; the rib index is approxi- the ¯anks forming a broad concavity just mately 7 based on the distance between two dorsal of mid¯ank. The rib index is approx- consecutive ribs. Ribs slant gently backward imately 5 based on the average distance be- on the dorsal third of the ¯anks and merge tween three consecutive ribs. Ribs break to form weak nodelike swellings on the mid- down into riblets on the ventral third of the ¯anks. The rib index on the dorsal third of ¯anks and slant strongly forward before dis- the ¯anks is approximately 7 based on the appearing on the ventrolateral shoulder. average distance between ®ve consecutive MAPS A2035c2 is a fragment of a body ribs. Ribs project strongly forward on the chamber 35.3 mm long (®g. 13E±H). The outer third of the ¯anks but are not preserved whorl height is 22.8 and 19.8 mm at the ad- on the venter. oral and adapical ends, respectively. The There are ®ve good examples of fairly whorl section is compressed ovoid with max- slender variants. MAPS A2035c3 is a small imum whorl width at midwhorl height; the fragment of a body chamer 29.2 mm long ratio of whorl width to height at the adoral (®g. 13A±D). The shell is slightly crushed end is 0.60. The dorsum is very broadly laterally and shows a shallow constriction rounded, and the dorsolateral shoulder is fair- along the ¯anks at midwhorl height on the ly abruptly rounded. The dorsal half of the left side, which may represent a growth de- ¯anks are ¯at and subparallel and the ventral formity. The whorl height is 17.3 and 15.5 half of the ¯anks are broadly rounded, and mm at the adoral and adapical ends, respec- converge to an abruptly rounded ventrolat- tively. The whorl section is compressed eral shoulder and a narrow, broadly rounded ovoid with a ratio of whorl width to height venter. Ribs cross the dorsum with a weak of 0.67 at the adoral end. The dorsum is convexity; the rib index is approximately 6 broadly rounded, and the dorsolateral shoul-

← Fig. 12. Ammonites from the Peedee Formation, Todd Marl Pit off Todd Road, approximately 2 km west of the Shallotte River, Brunswick County, North Carolina. A, B. Sphenodiscus lobatus (Tuomey, 1856), AMNH 48554. A, Right lateral; B, ventral. C±J. Discoscaphites gulosus (Morton, 1834). C, D. AMNH 48557, fragment, probably a macroconch. C, Right lateral; D, ventral. E±G. AMNH 48553, microconch. E, Right lateral; F, ventral; G, left lateral. H±J. AMNH 48551, macroconch. H, Right lateral; I, ventral; J, left lateral. All ®gures ϫ1. 32 AMERICAN MUSEUM NOVITATES NO. 3454

Fig. 13. A±Z, a±f. Baculites vertebralis Lamarck, 1801, AMNH loc. 3252, Severn Formation, Kent County, Maryland. A±D. MAPS A2035c3. A, Dorsal; B, ventral; C, left lateral; D, whorl cross section at adoral end. E±H. MAPS A2035c2. E, Right lateral; F, dorsal; G, ventral; H, whorl cross-section at adoral end. I±L. AMNH 47428. I, Right lateral; J, dorsal; K, ventral; L, whorl cross-section at adapical 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 33 der is fairly abruptly rounded. The ¯anks are end is 0.70. The whorl section is compressed nearly parallel to just dorsal of midwhorl ovoid with maximum width at midwhorl height and then converge more steeply to- height. The dorsum is more broadly rounded ward the venter. The venter is narrow and than the venter, and the ¯anks are very sharply rounded although this may be due in broadly rounded to ¯at. The specimen is part to lateral crushing. Faint ribs sweep nearly smooth with very faint ribs on the strongly forward on the ventral two-thirds of ventral half of the ¯anks and venter. Ribs the ¯anks; the rib index is 8 based on the cross the venter with a marked convexity; the average distance between three consecutive rib index is approximately 5.5 based on the ribs. average distance between three consecutive AMNH 47427 consists of four pieces ribs. comprising the adapical part of the body AMNH 49411 is a small, worn fragment chamber and last chamber of the phragmo- of a body chamber 29.0 mm long with a ta- cone (®g. 13U±X). Altogether, it is 56.0 mm per angle of 3.8Њ (®g. 13Y, Z, a, b). The long with a taper angle of 5.7Њ. The whorl whorl height is 14.8 and 13.4 mm at the ad- height is 18.2 and 13.5 mm at the adoral and oral and adapical ends, respectively. The ra- adapical ends, respectively. The whorl sec- tio of whorl width to height at the adoral end tion is compressed ovoid with maximum is 0.77. The whorl section is ovoid but slight- width at midwhorl height; the ratio of whorl ly more tear-shaped than in other specimens width to height at the adoral end is 0.66. The in the collection. The dorsum is very broadly dorsum is wide and broadly rounded and the rounded, and the dorsolateral shoulder is well dorsolateral shoulder is fairly abruptly round- rounded. The dorsal half of the ¯anks are ed. The dorsal half of the ¯anks are broadly nearly ¯at and the ventral half of the ¯anks rounded and divergent and the ventral half of are broadly rounded and converge to a nar- the ¯anks are broadly rounded and converge rowly rounded venter. The specimen is to a fairly abruptly rounded ventrolateral smooth except for weak ribs on the venter. shoulder and a narrow, broadly rounded ven- AMNH 49408 is a very small, smooth ter. No ornament is visible on the dorsum and septate fragment 15.3 mm long with a whorl dorsal third of the ¯anks because this part of height of 11.2 mm at the adoral end (®g. the specimen is worn. Ribs slant strongly for- 13c±f). The ratio of whorl width to height is ward on the ventral two-thirds of the ¯anks 0.67. The whorl section is compressed ovoid and intersect the line of the venter at an angle with the dorsum more broadly rounded than of 34Њ. The rib index is approximately 6 the venter. The suture shows narrow, rect- based on the distance between two consec- angular bi®d lobes and saddles (®g. 14A). utive ribs. Ribs cross the venter with a weak USNM 522939±522944 (not illustrated) convexity; the rib index is approximately 6.5 are fragments of body chambers 23.7±37.8 based on the average distance between three mm long, of which three are robust, one is consecutive ribs. intermediate, and two are slender. AMNH 49427 is a small fragment of a OCCURRENCE: Severn Formation, Kent body chamber 31.2 mm long (®g. 13M±P). County, Maryland; Severn Formation, Prince The whorl height is 12.1 and 10.1 mm at the Georges County, Maryland (Kennedy et al., adoral and adapical ends, respectively. The 1997). Elsewhere on the Atlantic Coastal ratio of whorl width to height at the adoral Plain, this species has been reported from the

← end. M±P. AMNH 49427. M, Dorsal; N, ventral; O, left lateral; P, whorl cross section at adoral end. Q±T. MAPS A2035c1. Q, Right lateral; R, dorsal; S, ventral; T, whorl cross section at adoral end. U±X. AMNH 47427. U, Right lateral; V, dorsal; W, ventral; X, whorl cross-section at adoral end. Y, Z, a, b. AMNH 49411. Y, Dorsal; Z, ventral; a, left lateral; b, whorl cross section at adoral end. c±f. AMNH 49408. c, Dorsal; d, ventral; e, left lateral; f, whorl cross section at adoral end. g±j. Eubaculites latecarinatus (Brunnschweiler, 1966), AMNH 49402, same locality as A±Z, a±f. g, Right lateral; h, dorsal; i, ventral; j, whorl cross-section at adoral end. All ®gures ϫ1. 34 AMERICAN MUSEUM NOVITATES NO. 3454

Fig. 14. A. Suture of Baculites vertebralis Lamarck, 1801, AMNH 49408, at a whorl height of 10.3 mm, AMNH loc. 3252, Severn Formation, Kent County, Maryland. B. Suture of Eubaculites latecarinatus (Brunnschweiler, 1966), AMNH 49402, at a whorl height of approximately 15 mm, same locality as A. upper part of the Navesink Formation and by original designation of Spath, 1926: 80; the lower part of the New Egypt Formation ϭ Baculites labyrinthicus Morton, 1834: 44, in Monmouth County, New Jersey (Landman pl. 13, ®g. 10. et al., in prep. c). According to Kennedy et al. (1997), this species occurs in western Eu- Eubaculites latecarinatus rope in the upper Maastrichtian Belemnitella (Brunnschweiler, 1966) junior and Belemnella kasimiroviensis bel- Figures 13g±j, 14B emnite zones. It is reported from the Maas- tricht area of Limburg, The Netherlands; the Eubaculites otacodensis (Stoliczka). Spath, 1940: Cotentin Peninsula, Manche, France; Petites 49 (pars), pl. 1, ®gs. 3a, b, text-®g. 1b. PyreÂneÂes, Haute Garonne, France; Belgium; Giralites latecarinatus Brunnschweiler, 1966: 33, Denmark; southern Sweden; northern Ger- pl. 3, ®gs. 13, 14; pl. 4, ®gs. 1±5; text-®gs. 17, many; Poland; southern Russia; Ukraine; 18. Turkmenia; Kazakstan; and Tunisia (see Giralites quadrisulcatus Brunnschweiler, 1966: 35, pl. 4, ®gs. 11±14, text-®g. 20. Klinger and Kennedy, 2001, for references). Eubaculites ambindensis Collignon, 1971: 18, pl. Genus Eubaculites Spath, 1926 646, ®g. 2393. (ϭ Giralites Brunnschweiler, 1966; Eubaculites latecarinatus (Brunnschweiler). Klinger, 1976: 91, pl. 40, ®g. 1; pl. 41, ®g. 3; pl. 42, ®gs. Cardabites Brunnschweiler, 1966; 2, 6; pl. 43, ®gs. 3, 4; text-®gs. 11d±e. Eubaculiceras Brunnschweiler, 1966) Eubaculites latecarinatus (Brunnschweiler). Klin- TYPE SPECIES: Baculites vagina var. oota- ger and Kennedy, in Klinger et al., 1980: 296, codensis Stoliczka, 1866: 199, pl. 90, ®g. 14, ®gs. 2a±c, 3a±d, 4a±c, 5b. 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 35

Eubaculites latecarinatus (Brunnschweiler, 1966). (2001) reported this species from the Maas- Henderson et al., 1992: 159, ®gs. 22L±N, 23N±P. trichtian of south India, Western Australia, Eubaculites latecarinatus (Brunnschweiler, 1966). Zululand, South Africa, the offshore Alphard Klinger and Kennedy, 1993: 238, ®gs. 26A, Group, and Madagascar. 39±41, 42B, C, 43±49, 50A, 52A. Eubaculites latecarinatus (Brunnschweiler, 1966). Kennedy et al., 1997: 20, ®gs. 15A±D, K, L, Eubaculites carinatus (Morton, 1834) 16G, H, 19. Figure 15P, Q Eubaculites latecarinatus (Brunnschweiler, 1966). Baculites carinatus Morton, 1834: 44, pl. 13, ®g. 1. Klinger and Kennedy, 2001: 234. Baculites lyelli d'Orbigny, 1847: pl. 1, ®gs. 3±7. Eubaculites latecarinatus (Brunnschweiler, 1966). Baculites tippaensis Conrad, 1858: 334, pl. 3, ®g. Klinger et al., 2001: 287, pl. 10, ®gs. 4±9, text- 27. ®g. 6. Baculites spillmani Conrad, 1858: 335, pl. 35, ®g. 24. TYPE: The holotype, by original designa- Baculites sheromingensis Crick, 1924: 139, pl. 9, tion, is the original of Brunnschweiler (1966: ®gs. 1±3. pl. 4, ®gs. 2±4) from the Maastrichtian of Eubaculites lyelli (d'Orbigny, 1847). Kennedy, Western Australia. 1987: 195, pl. 27, ®gs. 5±8; pl. 32, ®gs. 13, 14 MATERIAL: One specimen, AMNH 49402, (with full synonymy). an internal mold, from AMNH loc. 3252, the Eubaculites carinatus (Morton, 1834). Henderson Severn Formation, Kent County, Maryland. et al., 1992: 150, ®gs. 6F, G, 14±16, 17A±C, DESCRIPTION: AMNH 49402 is a small sep- G±J, 18±20. tate fragment 23.4 mm long (®g. 13g±j). It Eubaculites carinatus (Morton, 1834). Klinger is slightly crushed on the dorsum and right and Kennedy, 1993: 218, text-®gs. 7a±e, 21±30, 31a±g, 32±35, 36e, f, 37, 38, 42a, 52g, h. side. The whorl height is approximately 16.0 Eubaculites carinatus (Morton, 1834). Kennedy mm at the adoral end. The whorl section is and Cobban, 2000: 180, pl. 2, ®gs. 1±23, 27, ovoid with broadly rounded ¯anks. The ven- 28, text ®gs. 3, 4 (with additional synonymy). ter is narrow and tabulate with fairly sharp Eubaculites carinatus (Morton, 1834). Kennedy margins and is slightly slanted toward the et al., 2001: 168, ®g. 4a, e. right side due to crushing. The venter is cov- Eubaculites carinatus (Morton, 1834). Klinger et ered with faint ribs with a rib index of 6 al., 2001: 286, pl. 9, ®gs. 1±7; pl. 10, ®gs. 1± based on the average distance between ®ve 3; text-®g. 5. consecutive ribs. The suture is poorly pre- TYPE: The holotype, by monotypy, is served with deeply incised lobes and saddles ANSP 72866, the original of Morton (1834: (®g. 14B). pl. 13, ®g. 1) from the Maastrichtian Prairie DISCUSSION: Although this is a small spec- Bluff Chalk of Alabama. imen, it is identi®able by its smooth ¯anks MATERIAL: There is one specimen (USNM and tabulate venter with weak ribs. 525332) well enough preserved for positive OCCURRENCE: Severn Formation, Kent identi®cation from the Severn Formation, County, Maryland; Severn Formation, Prince Round Bay, Anne Arundel County, Mary- Georges County, Maryland (Kennedy et al., land. 1997). This species occurs in New Jersey in DESCRIPTION: USNM 525332 is a piece of the top of the New Egypt Formation and as a robust body chamber with most of the dor- reworked material at the base of the Hor- sum and nearly all of the right side stuck in nerstown Formation, near Eatontown, north- the matrix (®g. 15P, Q). It is approximately eastern Monmouth County (Landman et al., 37.1 mm long and is ornamented with coarse in prep. a); in the top of the New Egypt For- concave nodes on the dorsal two-thirds of the mation in the Crosswicks Creek Basin, ¯anks. The distance between consecutive southwestern Monmouth County (Landman nodes is approximately 9.7 mm, yielding a et al., in prep. c); and in the top of the Tinton rib index of approximately 3. The ventral Formation and as reworked material at the area is set off by a longitudinal groove, and base of the Hornerstown Formation near the ventrolateral shoulder is fairly abruptly Freehold, central Monmouth County (Land- rounded; the venter is ¯at and smooth. man et al., in prep. b). Klinger and Kennedy DISCUSSION: The combination of coarse 36 AMERICAN MUSEUM NOVITATES NO. 3454

Fig. 15. Ammonites from the upper part of the Severn Formation, Round Bay, presumably on the western shore of the Severn River, Anne Arundel County, Maryland. A, B, G±O. Discoscaphites iris (Conrad, 1858). A, B. USNM 525325, macroconch. A, Ventral; B, left lateral. G, H. USNM 525329, microconch. G, Right lateral; H, ventral. I. USNM 525328, macroconch, right lateral. J, K. USNM 525330, fragment. J, Ventral; K, left lateral. L, M. USMN 525327, microconch. L, Ventral; M, left lateral. N, O. USNM 525326, microconch. N, Right lateral; O, ventral. C, D. Discoscaphites cf. D. iris (Conrad, 1858), USNM 525323, macroconch. C, Left lateral; D, ventral. E, F. Discoscaphites cf. D. 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 37 nodes and a ¯at venter bordered by a longi- Eubaculites carinatus (Morton, 1834). Kennedy tudinal groove indicates that this specimen is and Cobban, 2000: 180, pl. 2, ®gs. 1±23, 27, Eubaculites carinatus. 28, text ®gs. 3, 4. OCCURRENCE: Severn Formation, Round MATERIAL: There are two specimens Bay, Anne Arundel County, Maryland; Sev- (USNM 525333 and 525334) from the Sev- ern Formation, Prince Georges County, ern Formation, Round Bay, Anne Arundel Maryland (Kennedy et al., 1997). This spe- County, Maryland. cies occurs in New Jersey in the top of the DESCRIPTION: USNM 525333 is a poorly New Egypt Formation and as reworked ma- preserved, somewhat distorted fragment, pre- terial at the base of the Hornerstown For- sumably of a body chamber, 83.4 mm long mation, near Eatontown, northeastern Mon- (®g. 15R). Most of what we interpret as the mouth County (Landman et al., in prep. a); venter and all of the left side are stuck in the in the top of the New Egypt Formation in the matrix. The dorsum is broadly rounded and Crosswicks Creek Basin, southwestern Mon- the dorsal half of the ¯anks are ornamented mouth County (Landman et al., in prep. c), with nodes with a rib index of approximately and at the Inversand Pit, near Sewell, 2.5. However, the venter is not exposed and Gloucester County (Kennedy and Cobban, we cannot determine if it is tabulate. 1996); and at the top of the Tinton Formation USNM 525334 (not illustrated) is a frag- and as reworked material at the base of the ment, presumably of a body chamber, 33.2 Hornerstown Formation near Freehold, cen- mm long. Although crushed, the dorsum tral Monmouth County (Landman et al., in seems broadly rounded and the venter seems prep. b). Kennedy and Cobban (1996: 802, tabulate. The ¯anks bear round, indistinct ®g. 3.1±3.3, 3.7±3.12; see also Kennedy et nodes with a rib index of approximately 2.5. al., 1995: ®gs. 4±6) recorded three speci- DISCUSSION: Both specimens are poorly mens of this species (USNM 12691a±c), ex preserved and incomplete but suggest kin- J.B. Marcou collection, labeled ``New Jer- ship with Eubaculites carinatus. sey'', which they inferred to be from the base OCCURRENCE: Severn Formation, Round of the Hornerstown Formation. This species Bay, Anne Arundel County, Maryland. is also reported from the top of the Corsicana Formation and base of the Kincaid Forma- SUPERFAMILY SCAPHITACEAE GILL, 1871 tion in Falls County, Texas (Kennedy et al., 2001); the Owl Creek Formation in Missis- FAMILY SCAPHITIDAE GILL, 1871 sippi, Missouri, and Tennessee (Kennedy and SUBFAMILY SCAPHITINAE GILL, 1871 Cobban, 2000); and the Prairie Bluff Chalk Genus Discoscaphites Meek, 1870 in Alabama and Mississippi (Cobban and Kennedy, 1995). Outside of North America, TYPE SPECIES: Ammonites conradi Morton, this species is reported from southeast 1834: 39, pl. 16, ®g. 3, by original designa- France, Austria, the Netherlands, Zululand, tion. South Africa, Mozambique, Madagascar, south India, Western Australia, Chile, Argen- Discoscaphites gulosus (Morton, 1834) tina, and California. It ranges from the upper Figures 12C±J, 16 lower to the upper upper Maastrichtian Ammonites conradi var. petechialis Morton, 1834: (Klinger et al., 2001). 39±40, pl. 16, ®g. 1. Ammonites conradi var. gulosus Morton, 1834: Eubaculites cf. E. carinatus (Morton, 1834) 39, pl. 16, ®g. 2. Figure 15R Ammonites conradi var. navicularis Morton, Compare: 1834: 40, pl. 19, ®g. 4. Baculites carinatus Morton, 1834: 44, pl. 13, ®g. 1. Discoscaphites gulosus (Morton, 1834). Landman

← minardi, n.sp., USNM 525324. E, Ventral; F, left lateral. P, Q. Eubaculites carinatus (Morton, 1834), USNM 525332. P, Ventral; Q, left lateral. R. Eubaculites cf. E. carinatus (Morton, 1834), USNM 525333, right lateral. All ®gures ϫ1. 38 AMERICAN MUSEUM NOVITATES NO. 3454

and Waage, 1993: 212, ®gs. 156, 157, 159, 160, 167±180 (with full synonymy). Discoscaphites gulosus (Morton, 1834). Cobban and Kennedy, 1995: 29, ®gs. 10.4, 10.5, 19.20± 19.24, 20.8±20.10, 20.14±20.17, 21.18±21.21. Discoscaphites gulosus (Morton, 1834). Kennedy et al., 1997: 21, ®gs. 20K±O, 21D, E. Discoscaphites gulosus (Morton, 1834). Kennedy et al., 2000: 26, ®g. 9G±I.

TYPE: The holotype is ANSP 51552 from the Prairie Bluff Chalk at Prairie Bluff, Al- abama. Fig. 16. Discoscaphites gulosus (Morton, MATERIAL: There are ®ve specimens from 1834), AMNH 50365, macroconch, Peedee For- the Peedee Formation, Brunswick County, mation, John D. Long County Park, Brunswick North Carolina. Four of them (AMNH County, North Carolina. A, Right lateral; B, ven- 48551, 48553, 48557, and 50328) were col- tral; C, left lateral. All ®gures ϫ1. lected from the Todd Marl Pit, approximately 2 km west of the Shallotte River, and one of them (AMNH 50365) was collected from slightly more prominent than those on the John D. Long County Park, Rt 33, 1.8 km ventrolateral margin. south of Rt 17, near Wilmington. AMNH 48557 is a fragment of the right MACROCONCH DESCRIPTION: AMNH 48551 side of the adoral part of the shaft of a body is an internal mold of a macroconch 55.6 mm chamber, probably a macroconch (®g. 12C, in diameter, missing part of the hook (®g. D). Ribs swing forward crossing the venter 12H±J). The umbilical seam of the body with a weak adoral projection; there are 9 chamber is straight in side view. The whorl ribs/cm on the venter. Five rows of tubercles section at the base of the body chamber is are present, including an umbilicolateral row, compressed subquadrate with a ratio of three ¯ank rows, and a ventrolateral row. The umbilicolateral and outermost ¯ank rows are whorl width to height of 0.58. The ¯anks are the most prominent. The distance between subparallel and broadly rounded. The ventro- consecutive tubercles in the outermost ¯ank lateral shoulder is abruptly rounded, and the row is 9.2 mm. The tubercles in the ventro- venter is narrow and well rounded. The lateral row are slightly more closely spaced whorl section becomes more robust in pass- with a distance between consecutive tuber- ing into the body chamber; the ratio of whorl cles of approximately 7 mm. width to height at midshaft is 0.67. The inner AMNH 50365 is a piece of a mature ¯anks are broadly rounded and divergent and phragmocone and adapical part of a body the outer ¯anks are nearly ¯at and conver- chamber, probably of a macroconch, half of gent. The ventrolateral shoulder is abruptly which is still stuck in the matrix (®g. 16). rounded and the venter is nearly ¯at. The umbilicus is exposed on the left side and The phragmocone bears ribs and tubercles, is 4.0 mm in diameter. Part of the umbilical although the tubercles on the ¯anks are poor- seam of the body chamber is preserved and ly preserved. The ventrolateral tubercles be- is straight in side view. The whorl width and come more widely spaced toward the base of height near the adoral end of the phragmo- the body chamber; the distance between the cone are 18.2 and 21.6 mm, respectively; the two most adoral tubercles is 5.5 mm. The ratio of whorl width to height is 0.84. The ornament on the body chamber is slightly ¯anks are broadly rounded, the ventrolateral better preserved on the left side and consists shoulder is abruptly rounded, and the venter entirely of tubercles. There is an umbilico- is nearly ¯at with a low ``keel'' in the mid- lateral row, three ¯ank rows, and a ventro- dle. Ribs are strong, broad, and rectiradiate lateral row. All of the tubercles are fairly or prorsiradiate on the inner half of the strong, although eroded, and widely spaced. ¯anks, with branching and intercalation at The tubercles on the outermost ¯anks are approximately midwhorl height. Ribs bear 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 39 six rows of tubercles including the ventro- the hook are covered with dense ribs that lateral row. Tubercles in the outermost ¯ank swing slightly backward at the ventrolateral and ventrolateral rows are nearly equal in shoulder and then forward, crossing the ven- size; the distance between consecutive tuber- ter with a moderately strong adoral projec- cles in each row is approximately 3 mm. tion. There are 10 or 11 ribs/cm on the ven- Outer ventrolateral tubercles are paired on ei- ter. ther side of the venter with each pair con- DISCUSSION: Of these specimens, only nected by a low, broad rib. AMNH 50365 (®g. 16) is as highly orna- MICROCONCH DESCRIPTION: AMNH 48553 mented as samples of this species from the is an internal mold of a body chamber 54.4 Severn Formation (e.g., Kennedy et al., mm long slightly crushed in on the adapical 1997: ®gs. 20K±O, 21D, E). AMNH 48553 end (®g. 12E±G). The aperture is well pre- (®g. 12E±G) displays an interesting combi- served and shows a deep constriction and a nation of characters. The presence of multi- moderately strong adoral projection of the ple rows of tubercles plus closely spaced rib- venter. The whorl section is subquadrate at bing on the hook with a relatively strong ad- midshaft with an intercostal ratio of whorl oral projection on the venter suggest kinship width to height of 0.66. The inner ¯anks are with Jeletzkytes (see, e.g., Kennedy et al. slightly concave and divergent and the outer [1997: ®gs. 22A±C, 23D, E] for illustrations ¯anks are broadly convex and convergent. of Jeletzkytes nebrascensis from the Severn The ventrolateral shoulder is fairly abruptly Formation). However, an important feature rounded and the venter is narrow and broadly of this specimen is that the outer ¯ank tu- rounded. The whorl section becomes more bercles are stronger than the ventrolateral tu- quadrate toward the aperture with an inter- bercles on most of the body chamber, which costal ratio of whorl width to height of 0.76. is more characteristic of Discoscaphites and The ¯anks are nearly ¯at and subparallel and Trachyscaphites than Jeletzkytes. We there- the venter is broad and nearly ¯at. fore treat this specimen as a microconch of The ornament is better preserved on the D. gulosus, closely similar in morphology to right side. A few ribs are present on the the co-occurring macroconchs. adapical end of the specimen. They appear OCCURRENCE: Peedee Formation, Bruns- at the umbilical shoulder and swing forward wick County, North Carolina; top of the New on the inner ¯anks, backward on the outer Egypt Formation and as reworked material at ¯anks, and then forward again on the ven- the base of the Hornerstown Formation, trolateral shoulder. The umbilical shoulder Monmouth County, New Jersey (Landman et bears three elongate bullae, the middle one al., in prep. a); New Egypt Formation, of which is the most prominent. There are Gloucester County, New Jersey (Kennedy et two rows of weak, irregularly spaced tuber- al., 2000); Severn Formation, Prince Georges cles on the inner ¯anks, a row of stronger County, Maryland (Kennedy et al., 1997); tubercles on the outer ¯anks, and a slightly and Prairie Bluff Chalk, Alabama and Mis- weaker row of tubercles on the ventrolateral sissippi (Cobban and Kennedy, 1995). In the margin. The outer ¯ank row consists of six Western Interior, Discoscaphites gulosus oc- more-or-less evenly spaced tubercles; the dis- curs in both the Hoploscaphites nicolletii and tance between consecutive tubercles at mid- Jeletzkytes nebrascensis zones in the Fox shaft is 7 mm. The ventrolateral row consists Hills Formation, South Dakota (Landman of eight tubercles, which are not as regularly and Waage, 1993). spaced as those of the outer ¯ank row; the distance between consecutive tubercles at midshaft is 5 mm. Except for the adapical Discoscaphites iris (Conrad, 1858) end of the specimen, the outer ¯ank tubercles Figures 15A, B, G±O, 17A±G, 18R are stronger than the ventrolateral tubercles, Scaphites iris Conrad, 1858: 335: pl. 35, ®g. 23. but this may be an artifact of preservation. Scaphites iris Conrad. Whit®eld, 1892: 265, pl. The outer ¯ank tubercles extend slightly ad- 44, ®gs. 4±7. oral of the ventrolateral tubercles and both Discoscaphites iris (Conrad). Stephenson, 1955: rows disappear on the hook. The ¯anks of 134, pl. 23, ®gs. 23±30. 40 AMERICAN MUSEUM NOVITATES NO. 3454 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 41

Discoscaphites iris (Conrad, 1858). Kennedy and prominent. The outer ventrolateral tubercles Cobban, 2000: 183, pl. 3, ®gs. 3±35, text-®g. 5. are worn away. TYPE: The holotype, ANSP 50589, is the USNM 525328 is a crushed fragment of a original illustrated in Conrad (1858: 335, pl. body chamber, possibly of a macroconch, 35, ®g. 23). It is from the bluffs of Owl with what appear to be four rows of large, Creek, Tippah County, Mississippi. eroded tubercles (®g. 15I). MATERIAL: There is one specimen (MAPS MAPS A2060c1 is a fragment of the mid- A2060c1) from the Severn Formation, shaft of a large, slightly in¯ated body cham- AMNH loc. 3252, Kent County, and six ber with all of the right side missing (®g. specimens (USNM 525325±525330) from 18R). There is a row of umbilicolateral bul- the Severn Formation, Round Bay, Anne lae and three rows of tubercles although al- Arundel County, Maryland. Three of the most all of the outer ventrolateral tubercles specimens from Round Bay (USNM are worn away. Four prorsiradiate umbilico- 525326±525328) are pinkish-buff in color, lateral bullae are spaced at approximately suggesting that they are weathered. It is pos- equal distances of 4±4.5 mm. Two relatively sible that they are from a different horizon prominent mid¯ank tubercles occur on the than the other specimens from Round Bay, adapical portion of the specimen followed but there is only one label for the entire lot. adorally by three much weaker, radial swell- MACROCONCH DESCRIPTION: USNM 525325 ings spaced at distances of approximately 4 is a fairly complete, although badly worn and mm. Five inner ventrolateral tubercles are slightly crushed, robust specimen 43.7 mm in preserved on the specimen and are evenly diameter (®g. 15A, B). The right side of the spaced at distances of 4.5±5.5 mm. At mid- phragmocone is still attached to the matrix. shaft, the distance between the umbilicola- The phragmocone is ornamented with fairly teral bullae and the mid¯ank tubercles (6 coarse, ¯exuous ribs that bear four rows of mm) is equal to that between the mid¯ank tubercles of which the umbilicolateral and in- tubercles and the inner ventrolateral tuber- ner and outer ventrolateral tubercles are the cles, which is greater than that between the most conspicuous. The distance between out- inner and outer ventrolateral tubercles (5 er ventrolateral tubercles on the adapical end mm). of the specimen is 2 mm. The hook of the MICROCONCH DESCRIPTION: USNM 525326 body chamber is eroded but the shaft pre- is a worn, slightly distorted adoral piece of a serves umbilicolateral, mid¯ank, and inner body chamber 33.6 mm long (®g. 15N, O). ventrolateral tubercles, of which the umbili- The ornament is better preserved on the right colateral and mid¯ank tubercles are the most side. There are four rows of tubercles that

← Fig. 17. Comparison of three closely related species of Discoscaphites. A±G. Discoscaphites iris (Conrad, 1858). A, B. USNM 522952, macroconch, U.S. Geological Survey loc. 25423, Owl Creek Formation, Tippah County, Mississippi. A, Ventral; B, left lateral. C, D. AMNH 50538, macroconch, AMNH loc. 3345, top of New Egypt Formation and base of Hornerstown Formation, Monmouth County, New Jersey. C. Ventral; D, left lateral. E. USNM 522955, microconch, same loc. as A, B, left lateral. F. USNM 522956, microconch, same loc. as A, B, left lateral. G. USNM 522957, microconch, same loc. as A, B, right lateral. H±M. Discoscaphites minardi, n.sp., macroconchs, AMNH loc. 3252, upper part of Severn Formation, Lloyd Creek, Kent County, Maryland. H, I. AMNH 47288. H, Right lateral; I, ventral. J, K. AMNH 47293. J, Right lateral; K, ventral. L, M. AMNH 50542. L, Right lateral; M, ventral. N±V. Discoscaphites conradi (Morton, 1834). N, O. MAPS 2031a1, fragment, Severn Forma- tion, exposures behind shopping center on south side of Central Avenue, just west of Beltway (Interstate 495), Randolph Village, Prince Georges County, Maryland. N, Ventral; O, left lateral. P, Q. MAPS A2031c2, fragment, Severn Formation, tributary of Cattail Brook, 1 km (0.6 mi) southwest of intersection of Sheriff and Brightseat roads, Brightseat, Prince Georges County, Maryland. P, Right lateral; Q, ventral. R, S. MAPS A2031c3, microconch, same loc. as P, Q. R, Right lateral; S, ventral. T±V. MAPS A2031c4, large macroconch, same loc. as P, Q. T, Right lateral; U, apertural; V, ventral. All ®gures ϫ1. 42 AMERICAN MUSEUM NOVITATES NO. 3454

Fig. 18. A±Q, S±Y. Discoscaphites minardi, n.sp., macroconchs, AMNH loc. 3252, Severn For- mation, Kent County, Maryland. A±D. Holotype, AMNH 47288. A, Right lateral; B, apertural; C, ventral; D, left lateral. E±G. AMNH 47281. E, Right lateral; F, ventral; G, left lateral. H±K. Paratype, AMNH 47293. H, Right lateral; I, apertural; J, ventral; K, left lateral. L±N. AMNH 47295. L, Right lateral; M, ventral; N, left lateral. O±Q. MAPS A2059a1. O, Apertural; P, ventral; Q, left lateral. S±U. Paratype, AMNH 50542. S, Right lateral; T, ventral; U, left lateral. V±Y. AMNH 47283. V, Right lateral; W, apertural; X, ventral; Y, left lateral. R. Discoscaphites iris (Conrad, 1858), MAPS A2060c1, same loc. as A±Q, S±Y, left lateral. All ®gures ϫ1. 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 43 occur on coarse, poorly de®ned ribs that be- et al., in prep. c); and in the top of the Tinton come more closely spaced toward the aper- Formation and as reworked material at the ture. Only two umbilicolateral tubercles are base of the Hornerstown Formation near preserved. Of the other rows, the inner ven- Freehold, central Monmouth County (Land- trolateral tubercles are the largest. man et al., in prep. b). It occurs on the Gulf USNM 525329 is part of the adoral half Coastal Plain in the upper part of the Owl of a body chamber with the left side still em- Creek Formation and as reworked material at bedded in the matrix (®g. 15G, H). The um- the base of the Clayton Formation in Missis- bilical seam is curved in side view and sippi, Tennessee, and Missouri (Stephenson, matches the curve of the venter, indicating it 1955; Sohl, 1960, 1964; Kennedy and Cob- is a microconch. The umbilical wall is ¯at ban, 2000). This species denotes the D. iris and gently inclined outward and the umbili- Zone on the Gulf and Atlantic Coastal Plain, cal shoulder is abruptly rounded. The inner which represents the upper part of the upper and middle ¯anks are nearly ¯at and slightly Maastrichtian, corresponding to the upper convergent and the outer ¯anks between the part of calcareous nannofossil Subzone inner and outer ventrolateral tubercles are CC26b. broadly rounded and more steeply convergent. The ventrolateral shoulder is fairly Discoscaphites cf. D. iris (Conrad, 1858) abruptly rounded and the venter is broadly Figure 15C, D rounded. Four rows of tubercles are present. The Compare: umbilicolateral row is perched on the umbil- Scaphites iris Conrad, 1858: 335, pl. 35, ®g. 23. Discoscaphites iris (Conrad, 1858). Kennedy and ical shoulder and consists of three tubercles, Cobban, 2000: 183, pl. 3, ®gs. 3±35, text-®g. 5. the middle one of which is the most prominent one on the specimen. There are four MATERIAL: There is a single specimen mid¯ank, four inner ventrolateral, and ®ve (USNM 525323) from the Severn Formation, outer ventrolateral tubercles preserved. The Round Bay, Anne Arundel County, Mary- outer ventrolateral tubercles are slightly more land. subdued than the inner ones. The distance DESCRIPTION: USNM 525323 is the adoral between consecutive tubercles in each row is half of a robust body chamber with the dor- 5±5.5 mm. The distance between tubercle sum still attached to the matrix (®g. 15C, D). rows on the middle of the specimen starting Part of the aperture appears to be preserved with the umbilicolateral tubercles is 5.5, 4.5, on the right side. There is an umbilical bulge and 4 mm. The distance between outer ven- on the middle of the specimen on the left side trolateral tubercles on either side of the ven- indicating it is a macroconch. The inner and ter is 4 mm. mid¯anks are well rounded with a swelling DISCUSSION: Although fragmentary, all on the mid¯anks on the left side; the outer these specimens conform to the description ¯anks between the inner and outer ventrolat- of Discoscaphites iris, notably in having four eral tubercles are broadly rounded to nearly fairly prominent rows of tubercles. They are ¯at. The ventrolateral shoulder is fairly indistinguishable from specimens of this spe- abruptly rounded and the venter is nearly ¯at. cies from the Owl Creek Formation, Missis- The preserved ornament consists of ®ne sippi (®g. 17A±G). ribs, umbilical bullae, mid¯ank bullae, and OCCURRENCE: Upper part of the Severn inner and outer ventrolateral tubercles. One Formation, Kent and Anne Arundel Coun- prominent umbilical crescentic bulla appears ties, Maryland. This species occurs in New near the dorsal margin on the middle of the Jersey in the top of the New Egypt Forma- specimen. Ribs are indistinct on the adapical tion and as reworked material at the base of half of the specimen, but are conspicuous on the Hornerstown Formation, near Eatontown, the hook. Ribs are sharp and thin and bear northeastern Monmouth County (Landman et radial bullae on the midfanks. Ribs swing al., in prep. a); in the top of the New Egypt gently forward just dorsal of the row of inner Formation in the Crosswicks Creek Basin, ventrolateral tubercles, crossing the venter southwestern Monmouth County (Landman with a slight adoral projection; there are 12 44 AMERICAN MUSEUM NOVITATES NO. 3454 ribs/cm on the venter. Seven inner ventrolat- species; ¯anks of body chamber are ¯at and eral tubercles are preserved on the left side subparallel to slightly convergent; ornament spaced at distances of 4.5 mm on the adap- on body chamber consists of weak, slightly ical end of the specimen and 3 mm on the swollen prorsiradiate ribs bearing concave adoral end. They become smaller and slightly umbilicolateral bullae, very weak, radial more bullate toward the aperture. There are mid¯ank swellings, if any at all, and an ap- nine outer ventrolateral tubercles preserved proximately equal number of inner and outer on the left side; they show the same spacing ventrolateral tubercles; inner ventrolateral tu- as the inner ventrolateral tubercles and be- bercles are as strong as or slightly stronger come smaller and more closely spaced to- than the outer ventrolateral tubercles. ward the aperture. On the adoral third of the DESCRIPTION: This species is relatively body chamber coincident with the appear- small with the macroconch approximately 40 ance of conspicuous ribbing, the rows of in- mm in maximum diameter and the micro- ner and outer ventrolateral tubercles, espe- conch approximately two-thirds as large. The cially on the right side, are both shifted to- hook is only slightly re¯ected with an aper- ward the venter, possibly due to a pathology. tural angle in macroconchs of 40±50Њ. The DISCUSSION: This specimen resembles Dis- shell is compressed with relatively ¯at coscaphites iris in its robust whorl section ¯anks; the ratio of whorl width to height at and well-developed rows of inner and outer midshaft averages approximately 0.70. There ventrolateral tubercles. However, it differs in are four rows of tubercles on indistinct pror- that the mid¯ank tubercles are only repre- siradiate ribs, which are more closely spaced sented by small bullae and that very ®ne ribs near the aperture. The umbilicolateral bullae cover the adoral third of the specimen. are crescentic and become progressively OCCURRENCE: Severn Formation, Round more prorsiradiate adorally. The mid¯ank Bay, Anne Arundel County, Maryland. swellings are weak and elongated radially, although occasionally they are round. In a Discoscaphites minardi, new species few instances, they do not exist at all, which Figures 17H±M, 18A±Q, S-Y, 19±22 may be due to poor preservation. The inner ventrolateral tubercles are usually pointed TYPES: The holotype is AMNH 47288, a but sometimes are elongated radially. There macroconch, and the paratypes are AMNH are an equal number of outer ventrolateral 47293 and 50542, both macroconchs, and tubercles, which are as strong as or slightly AMNH 47289, 47292, and 47297, all micro- weaker than the inner ventrolateral tubercles. conchs, from AMNH loc. 3252, the Severn The tubercles in both rows are evenly spaced Formation, Kent County, Maryland. at distances of 4±5 mm. The smallest dis- ETYMOLOGY: After James P. Minard, a ge- tance between tubercle rows is between the ologist at the U.S. Geological Survey, who rows of inner and outer ventrolateral tuber- worked on the stratigraphy of the Atlantic cles (®g. 22). This distance is as little as half Coastal Plain and discovered the locality the distance between other, adjacent rows of where this species occurs. tubercles. The position of the mid¯ank swell- MATERIAL: There are 32 specimens: 10 ings is approximately midway between the macroconchs (AMNH 47281, 47283, 47288, umbilicolateral bullae and the inner ventro- 47290, 47293, 47295, 47299, 49406, 50542, lateral tubercles. However, there is some var- and MAPS A2059a1); 6 microconchs iation depending on the dimorph. In macro- (AMNH 47286, 47289, 47292, 47294, conchs, the mid¯ank swellings are slightly 47297, and 49426); and 16 specimens too closer to the inner ventrolateral tubercles, fragmentary to determine the dimorph whereas in microconchs, they are midway (AMNH 47280, 47282, 47285, 47287, between or closer to the umbilicolateral bul- 47296, 47298, 47479, 49407, 49414, 49422± lae. This difference is probably related to the 25, 50536, and 50537, and USNM 522938), difference in whorl height between di- from AMNH loc. 3252, the upper part of the morphs. Severn Formation, Kent County, Maryland. Because much of the fossil material is DIAGNOSIS: Relatively small, dimorphic poorly preserved and fragmentary, we de- 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 45 scribe several specimens to document the onto the hook but this is impossible to con- morphology of this species as fully as pos- ®rm because of poor preservation. There is sible. Even so, there is no complete adult and a row of relatively prominent inner ventro- only one specimen (AMNH 47289) pre- lateral tubercles that are spaced at distances serves any details of the hook. of approximately 4±5 mm at midshaft, be- MACROCONCH DESCRIPTION: The holotype coming more closely spaced adorally. A row AMNH 47288 is an adult specimen 40.9 mm of slightly less prominent but equally spaced in maximum diameter with the adoral half of outer ventrolateral tubercles is also present. the phragmocone and most of the body At midshaft, the distance between the um- chamber preserved except for part of the bilicolateral bullae and the mid¯ank swell- adapical quarter of the shaft and the venter ings (6 mm) is slightly greater than that be- of the hook (®gs. 17H, I, 18A±D). The um- tween the mid¯ank swellings and the inner bilical shoulder of the shaft is straight in side ventrolateral tubercles (5.5 mm), which is, in view. The whorl section at midshaft is rela- turn, slightly greater than that between the tively compressed with a slightly swollen inner and outer ventrolateral tubercles (4 outline. The whorl width and height at mid- mm) (®g. 22). The venter is worn and does shaft are 13.6 and 20.1 mm, respectively; the not preserve any ribbing. ratio of whorl width to height is 0.68. The Paratype AMNH 47293 is most of an adult umbilical wall is steep and sharply convex 42.0 mm in maximum diameter (®gs. 17J, K, and the umbilical shoulder is abruptly round- 18H±K). It is missing most of the phrag- ed. The inner ¯anks are broadly rounded and mocone, except for the adoral half, and most gently divergent, the mid¯anks are nearly ¯at of the aperture, and it is badly worn on the and gently convergent, and the outer ¯anks left side. The body chamber occupies ap- are broadly rounded and more steeply con- proximately one-half whorl; the apertural an- vergent. The ventrolateral shoulder is fairly gle is 46Њ. The umbilical shoulder is straight abruptly rounded and the venter is very in side view with a very slight bulge. The broadly rounded. specimen is somewhat distorted but original- Part of the ornament is visible on the outer ly was very compressed. The whorl width ¯anks and venter on the adapical portion of and height at the base of the body chamber the preserved phragmocone. Ribs are pror- are 10.9 and 17.3 mm, respectively; the ratio siradiate on the outermost ¯anks and link to of whorl width to height is 0.63. The whorl small ventrolateral tubercles that are evenly section is equally compressed at midshaft; spaced at distances of approximately 2.5 the whorl width and height are 11.9 and 19.7 mm. It is possible that there is a row of inner mm, respectively; the ratio of whorl width to ventrolateral tubercles but they are dif®cult height is 0.60. The umbilical wall is vertical to detect because of poor preservation. Ribs and steeply convex and the umbilical shoul- are present on the venter of the most adapical der is abruptly rounded. The inner ¯anks are part of the preserved phragmocone. They are broadly rounded, the mid¯anks are ¯at to evenly spaced at distances of 0.75 mm (ഠ 14 slightly concave and gently convergent, and ribs/cm) and show a slight adoral projection. the outermost ¯anks between the inner and The ornament on the body chamber is outer ventrolateral tubercles are broadly weak; the most obvious features are the um- rounded and more steeply convergent. bilicolateral bullae and inner and outer ven- The ornament is only preserved on the trolateral tubercles. There are four umbili- right side of the body chamber. Tubercles and colateral bullae on the right side that extend bullae occur on weak, prorsiradiate ribs. to the aperture. They are strong and arcuate There are four concave umbilicolateral bul- at midshaft where they are evenly spaced at lae, the most adoral of which is the smallest distances of approximately 4.5 mm. They and occurs at the apertural margin. They are give rise to weak, straight prorsiradiate ribs. evenly spaced at distances of 3.5±4 mm on Faint radial swellings occur at mid¯ank and the shaft and are linked by weak, straight are most noticeable on the adoral half of the prorsiradiate ribs to very weak, radial midshaft where they are spaced at distances of ¯ank swellings, of which ®ve are visible approximately 2.5 mm. They may extend spaced at distances of approximately 3 mm 46 AMERICAN MUSEUM NOVITATES NO. 3454

Fig. 19. Discoscaphites minardi, n.sp., AMNH loc. 3252, Severn Formation, Kent County, Mary- land. A±K. Macroconchs. A±C. AMNH 49406. A, Right lateral; B, apertural; C, ventral. D±G. AMNH 47290. D, Right lateral; E, apertural; F, ventral; G, left lateral. H±K. AMNH 47299. H, Right lateral, I, apertural; J, ventral; K, left lateral. L±Z, a±g. Microconchs. L, M. AMNH 47294. L, Right lateral; M, ventral. N±Q, AMNH 47289. N, Right lateral; O, apertural; P, ventral; Q, left lateral. R, S. AMNH 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 47 at midshaft. Due to poor preservation, it is ner and outer ventrolateral tubercles. The dif®cult to determine if these mid¯ank swell- umbilicolateral bullae are spaced at distances ings extend onto the hook. Ribs are stronger of 5.5±7.5 mm at midshaft. The mid¯ank and more closely spaced toward the aperture. swellings, of which there are three, are more There is a row of 13 inner ventrolateral tu- pronounced on the left side. The swellings bercles (allowing for one lost due to preser- are round and faint and are spaced at dis- vation) that extend to the aperture (although tances of 3.25±4 mm. The inner row of ven- the apertural lip is missing). These tubercles trolateral tubercles is slightly more promi- are evenly spaced on the shaft at distances of nent than the outer row. At midshaft, the in- approximately 5 mm but become more close- ner ventrolateral tubercles are spaced at dis- ly spaced toward the aperture. A row of tances of 5 mm and the outer ventrolateral equally strong outer ventrolateral tubercles is tubercles at distances of 6 mm. The two rows also present but is worn away on most of the are very close to each other so that in a few shell. On the adapical third of the body instances, tubercles from adjacent rows share chamber where these tubercles are preserved, a common base. On the adapical part of the they are equal in number and spacing to the body chamber on the left side where the tu- inner ventrolateral tubercles. At midshaft, the bercles in both rows can be counted, there distance between the umbilicolateral bullae are ®ve tubercles in each row. At midshaft, and the mid¯ank swellings (6 mm) is slightly the distance between the umbilicolateral bul- greater than that between the mid¯ank swell- lae and the mid¯ank swellings (7 mm) is ings and the inner ventrolateral tubercles (5.5 much greater than that between the mid¯ank mm), which, in turn, is much greater than swellings and the inner ventrolateral tuber- that between the inner and outer ventrolateral cles (5 mm), which is equal to that between tubercles (3 mm) (®g. 22). No ribs are pre- the inner and outer ventrolateral tubercles sent on the venter, although most of the ven- (®g. 22). There is a single errant tubercle be- ter is worn away. tween the two ventrolateral rows on the right Paratype AMNH 50542 is a crushed piece side, although it may be laterally displaced of the adoral part of an adult phragmocone due to crushing. No ribs are preserved on the and adapical part of the body chamber (®gs. venter. 17L, M, 18S±U). It was probably originally The rest of the macroconchs in the collec- compressed. The phragmocone bears straight tion are fragmentary. We describe ®ve of rectiradiate ribs that bifurcate on the outer- them to further document the morphology of most ¯anks. On the adapical part of the pre- the species. AMNH 47281 is a fragment of served phragmocone, only the outer ventro- a compressed body chamber missing part of lateral tubercles are visible; they become the adapical end and hook (®g. 18E±G). The slightly more widely spaced adorally so that umbilical wall is straight in side view. The the distance between the two most adoral tu- whorl section at midshaft is compressed bercles on the phragmocone is 4 mm. A row ovoid; the whorl width and height are 12.8 of inner ventrolateral tubercles appears at the and 19.2 mm, respectively; the ratio of whorl adoral end of the phragmocone. The distance width to height is 0.67. The umbilical wall between inner ventrolateral tubercles at the is steep and sharply convex and the umbilical base of the body chamber is 5 mm. shoulder is abruptly rounded. The inner The ornament on the body chamber con- ¯anks are broadly rounded and gently diver- sists of fairly strong, arcuate, umbilicolateral gent, the mid¯anks are ¯at and gently con- bullae, very faint swellings at approximately vergent, and the outermost ¯anks are very two-thirds whorl height, and fairly strong in- broadly rounded and more steeply conver-

← 47286. R, Ventral; S, left lateral. T±W. AMNH 47297. T, Right lateral; U, apertural; V, ventral; W, left lateral. X±Z, a. AMNH 49426. X, Right lateral; Y, apertural; Z, ventral; a, left lateral. b±e. AMNH 47292. b, Right lateral; c, apertural; d, ventral; e, left lateral. f, g. AMNH 47287. f, Ventral; g, left lateral. All ®gures ϫ1. 48 AMERICAN MUSEUM NOVITATES NO. 3454

Fig. 20. Discoscaphites minardi, n.sp., dimorph indeterminate, AMNH loc. 3252, Severn Formation, Kent County, Maryland. A±D. AMNH 47298. A, Right lateral; B, apertural; C, ventral; D, left lateral. E±H. AMNH 49425. E, Right lateral, F, apertural; G, ventral; H, left lateral. I. AMNH 47296, left lateral. J±L. AMNH 47280. J, Right lateral; K, ventral; L, left lateral. M±O. AMNH 47479. M, Right lateral; N, apertural; O, ventral. P, Q. AMNH 49422. P, Right lateral; Q, ventral. R±U. AMNH 49424. R, Right lateral; S, apertural; T, ventral; U, left lateral. V±Y. AMNH 47285. V, Right lateral; W, apertural; X, ventral; Y, left lateral. All ®gures ϫ1. gent. The ventrolateral shoulder is fairly bercles on the fragment are almost the same abruptly rounded and the venter is nearly ¯at. (8 inner, 9 outer ventrolateral tubercles). At The ornament on the body chamber is bet- midshaft, the distance between the umbili- ter preserved on the right side and consists colateral bullae and mid¯ank swellings (8.5 of umbilicolateral bullae, very faint mid¯ank mm) is much greater than that between the swellings, inner and outer ventrolateral tu- mid¯ank swellings and the inner ventrolat- bercles, and convex prorsiradiate ribs on the eral tubercles (5 mm), which, in turn, is adoral half of the shaft. Three umbilicolateral slightly greater than that between the inner bullae are present and are evenly spaced at and outer ventrolateral tubercles (4 mm) (®g. distances of approximately 5 mm. The mid- 22). The distance between outer ventrolateral ¯ank swellings are weak, radial, and occur tubercles on either side of the venter is 5 on prorsiradiate ribs. Two swellings are vis- mm. ible spaced 5 mm apart. They are linked by AMNH 47283 is most of the shaft of a ribs to the inner ventrolateral tubercles. Both body chamber missing the venter and outer rows of ventrolateral tubercles are well de- ¯anks on the adoral end (®g. 18V±Y). The veloped with the inner row being slightly whorl section at the base of the body cham- stronger than the outer row. The distance be- ber is compressed ovoid; the whorl width and tween tubercles within each row is 4.5±5.5 height are 9.1 and 13.9 mm, respectively; the mm with maximum spacing at midshaft. The ratio of whorl width to height is 0.65. The numbers of inner and outer ventrolateral tu- whorl section is slightly more depressed at 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 49

Fig. 21. Sutures of Discoscaphites minardi, n.sp., AMNH loc. 3252, Severn Formation, Kent Coun- ty, Maryland. A. AMNH 47298, at a whorl height of approximately 12.0 mm. B. AMNH 47294, last suture at a whorl height of 9.4 mm. midshaft; the whorl width and height are elongate swellings on the mid¯ank starting 11.4 and 16.1 mm, respectively; the ratio of just adoral of midshaft; they are spaced at whorl width to height is 0.71. The umbilical equal distances of 2.5±3 mm. The inner ven- wall is steep and sharply convex and the um- trolateral tubercles are much stronger than bilical shoulder is abruptly rounded. The in- the mid¯ank swellings. There are eight inner ner ¯anks are broadly rounded and slightly ventrolateral tubercles preserved on the body divergent, the mid¯anks are nearly ¯at and chamber fragment; they are spaced at equal slightly convergent, and the outermost ¯anks distances of 4.5 mm. The outer ventrolateral are broadly rounded and more steeply con- tubercles are slightly more subdued and are vergent. The ventrolateral shoulder is fairly approximately evenly spaced at distances of abruptly rounded and the venter is broadly 4.5±5.5 mm. At midshaft, the distance be- rounded to ¯at. tween the umbilicolateral bullae and mid- The body chamber is ornamented with ¯ank tubercles (5.5 mm) is slightly greater umbilicolateral bullae, faint mid¯ank swell- than that between the mid¯ank swellings and ings, and inner and outer ventrolateral tuber- the inner ventrolateral tubercles (5.0 mm), cles. The ornament is slightly better pre- which, in turn, is much greater than that be- served on the left side. There is a straight tween the inner and outer ventrolateral tu- prorsiradiate rib connecting an umbilicolater- bercles (3.5 mm) (®g. 22). Although the ven- al bulla and a mid¯ank swelling just adoral ter is smooth, it is raised into undulations of midshaft. The umbilicolateral bullae orig- connecting outer ventrolateral tubercles on inate on the umbilical shoulder and become either side of the venter on the adapical part progressively more prorsiradiate adorally. of the specimen. The distance between umbilicolateral bullae AMNH 49406 consists of the adoral part at midshaft is 5 mm. There are three weak, of the phragmocone and adapical part of the 50 AMERICAN MUSEUM NOVITATES NO. 3454

Fig. 22. Relative spacing of tubercle rows in Discoscaphites minardi, n.sp. In each specimen, the umbilicolateral bullae (ul) and outer ventrolateral tubercles (ovl) are plotted on the left and right side, respectively, with the mid¯ank swellings (mf) and inner ventrolateral tubercles (ivl) in between. M, macroconch; m, microconch. body chamber (®g. 19A±C). The right side on widely spaced, straight to slightly sinu- is better preserved. The whorl section is ous, prorsiradiate ribs that link to inner ven- compressed ovoid at midshaft. The umbilical trolateral tubercles. The two most adoral ribs wall is steep and convex and the umbilical bear feeble mid¯ank swellings. The ribs shoulder is sharply rounded. The inner ¯anks weaken and the ¯anks become smoother in are broadly rounded and divergent, the mid- the region between the mid¯ank swellings ¯anks are ¯at to concave and convergent, and the inner ventrolateral tubercles. The in- and the outer ¯anks are broadly rounded and ner ventrolateral tubercles are radially elon- more steeply convergent. The ventrolateral gated and ®rst appear on the adapical part of shoulder is fairly abruptly rounded and the the body chamber. They become progres- venter is ¯at. sively more widely spaced adorally; the dis- The ¯anks of the phragmocone are cov- tance between tubercles at midshaft is 4.5 ered with slightly swollen straight ribs. There mm. The inner and outer ventrolateral tuber- are three crescentic umbilicolateral bullae on cles are very close to each other so that in a the body chamber that become progressively few instances tubercles from adjacent rows more prorsiradiate adorally. The bullae occur share a common base. The outer ventrolateral 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 51 tubercles ®rst appear slightly adapical of the mm, respectively; the ratio of whorl width to inner ventrolateral tubercles and are spaced height is 0.71. The umbilical wall is steep somewhat unevenly with a maximum dis- and convex, becoming more broadly rounded tance of 6 mm between tubercles just adap- adorally; the umbilical shoulder is fairly ical of midshaft. The distance between the abruptly rounded. The inner ¯anks are broad- umblicolateral bullae and the mid¯ank swell- ly rounded, the mid¯anks are nearly ¯at and ings (4.5 mm) is equal to that between the slightly convergent, and the outermost ¯anks mid¯ank swellings and the inner ventrolat- between the inner and outer ventrolateral tu- eral tubercles, which is much greater than bercles are broadly rounded and more steeply that between the inner and outer ventrolateral convergent. The ventrolateral shoulder is tubercles (3 mm) (®g. 22). No ribbing is pre- fairly abruptly rounded and the venter is sent on the venter. broadly rounded to ¯at. AMNH 47299 is a fragment of the adap- The ornament is different on the right and ical half of a body chamber with the umbil- left side. The left side bears four rows of tu- ical area worn away (®g. 19H±K). It is pre- bercles with only a single row of two weak sumably a macroconch. The ornament is bet- mid¯ank tubercles on the adoral half of the ter preserved on the left side and consists of specimen. In contrast, there are ®ve rows of umbilicolateral bullae, mid¯ank swellings, tubercles on the right side, including two inner and outer ventrolateral tubercles, and rows of mid¯ank tubercles on either side of prorsiradiate ribs. There are three concave midwhorl height. The more dorsal row, umbilicolateral bullae spaced at approxi- which more nearly corresponds to the mid- mately equal distances of 4.5±5.5 mm. The ¯ank row on the left side, consists of three most adoral bulla is the most prorsiradiate; tubercles, one very weak and two slightly the most adapical bulla occurs on a swollen stronger, spaced at distances of 3.5 mm on rib, which is convex on the ¯anks and ex- the adoral end of the specimen. The more tends to an inner ventrolateral tubercle. ventral row consists of ®ve tubercles, which Weak, straight prorsiradiate ribs extend are as strong as the strongest tubercles in the across the mid¯anks at midshaft. Two swell- more dorsal row, and are spaced at equal dis- ings occur at midwhorl height, the adapical tances of 4 mm on nearly the entire speci- one of which is linked by a strongly convex men. Four umbilicolateral bullae are present rib to an inner ventrolateral tubercle. Both on the right side with a spacing of 5 mm the inner and outer ventrolateral tubercles are between consecutive bullae at midshaft. The equally strong and spaced at approximately inner and outer ventrolateral tubercles are equal distances of 5.5±6 mm. The number of slightly weaker than the umbilicolateral bul- tubercles in each row is nearly the same (5 lae but stronger than the mid¯ank tubercles. inner and 6 outer ventrolateral tubercles). There are six inner ventrolateral tubercles Each outer ventrolateral tubercle is spaced evenly spaced at distances of 4.75 mm on the slightly adapical of the adjacent inner ven- right side. As shown on the left side (there trolateral tubercle. The distance between the is some erosion on the right side), the outer umbilicolateral bullae and the mid¯ank ventrolateral tubercles are as strong as the swellings (5.5 mm) is slightly greater than inner ones; they are spaced at distances of that between the mid¯ank swellings and the 3.75±5 mm. inner ventrolateral tubercles (5 mm), which, MICROCONCH DESCRIPTION: Paratype in turn, is much greater than that between the AMNH 47297 is the adapical two-thirds of inner and outer ventrolateral tubercles (4 a body chamber of a ¯at-sided specimen mm) (®g. 22). The distance between outer missing part of the venter on the adapical end ventrolateral tubercles on either side of the (®g. 19T±W). The whorl width and height at venter is 5.5 mm. There are no ribs on the midshaft are 9.1 and 14.6 mm, respectively; venter. the ratio of whorl width to height is 0.62. The AMNH 47290 is the adapical half of a umbilical wall is steep and sharply convex fairly robust body chamber (®g. 19D±G). on the adapical part, becoming more broadly The whorl section is subquadrate at midshaft; rounded and inclined outward at midshaft. whorl width and height are 12.4 and 17.5 Likewise, the umbilical shoulder becomes 52 AMERICAN MUSEUM NOVITATES NO. 3454 less abruptly rounded adorally. The mid- mately 2.5 mm. Ribs bifurcate on the mid- ¯anks are nearly ¯at to weakly concave and ¯anks and develop weak radial swellings. slightly convergent and the outer ¯anks be- One such swelling is particularly prominent tween the inner and outer ventrolateral tu- on the adoral end of the specimen on the left bercles are more broadly rounded and more side. There are nine inner ventrolateral tu- steeply convergent. The ventrolateral shoul- bercles on the left side spaced at distances of der is fairly abruptly rounded and the venter 3±4.5 mm at midshaft. A row of two very is nearly ¯at. faint swellings occurs just dorsal of the inner The ¯anks are ornamented with swollen, ventrolateral row on the right side. Most of widely spaced, straight to convex ribs that the outer ventrolateral tubercles are not pre- bear umbilicolateral bullae and inner ventro- served, but on the adapical part of the spec- lateral tubercles. Three umbilicolateral bullae imen where they are present, they show ap- are preserved on the right side with a spacing proximately the same spacing as the inner of 6.5 mm between the two most adoral bul- ventrolateral tuberclesÐapproximately 4 mm lae. The tiny inner ventrolateral tubercles are between consecutive tubercles just adapical irregularly distributed, perhaps due to a pa- of midshaft. The venter bears two swollen thology, with the distance between tubercles undulations on the adapical part of the spec- equaling 5.5, 10, and 4 mm, as measured in imen connecting outer ventrolateral tubercles an adoral direction on the right side. The out- on either side of the venter. The distance be- er ventrolateral tubercles are very weak, tween the umbilicolateral bullae and the mid- probably due to poor preservation. They are ¯ank swellings (4 mm) is slightly less than approximately evenly spaced at distances of that between the mid¯ank swellings and the 5 mm at midshaft. There are very faint, radial inner ventrolateral tubercles (5 mm), which mid¯ank swellings on the adoral half of the is slightly greater than that between the inner specimen on the right side. The distance be- and outer ventrolateral tubercles (4 mm) (®g. tween the umbilicolateral bullae and mid- 22). ¯ank swellings (4.75 mm) is equal to that Paratype AMNH 47289 consists of most between the mid¯ank swellings and the inner of a body chamber, presumably of a micro- ventrolateral tubercles, which is greater than conch (®g. 19N±Q). However, the umbilical that between the inner and outer ventrolateral seam is straight in side view, suggesting that tubercles (2.5 mm) (®g. 22). it could equally be an elongate macroconch. Paratype AMNH 47292 is most of the The impression of the phragmocone is visi- adapical half of a body chamber with part of ble and shows that there was no gap between the inner whorls attached (®g. 19b±e). The the phragmocone and the hook. Parts of the whorl section at midshaft is compressed dorsal projection and apertural constriction ovoid; the whorl width and height are 11.4 are present. The whorl section at midshaft is and 16.6 mm, respectively; the ratio of whorl compressed ovoid; the whorl width and width to height is 0.69. The umbilical wall height are 11.3 and 15.6 mm, respectively; is steep and sharply convex and the umbilical the ratio of whorl width to height is 0.72. The shoulder is abruptly rounded. The inner umbilical wall is steep and sharply convex at ¯anks are broadly rounded and slightly di- midshaft, becoming more broadly rounded vergent, the mid¯anks are nearly ¯at and near the aperture. Likewise, the umbilical slightly convergent, and the outer ¯anks are shoulder becomes less abruptly rounded broadly rounded and more steeply conver- adorally. The inner ¯anks are broadly round- gent. The ventrolateral shoulder is fairly ed, the mid¯anks are ¯at and subparallel, and abruptly rounded and the venter is broadly the outer ¯anks are broadly rounded. The rounded. ventrolateral shoulder is fairly abruptly The ¯anks are ornamented with slightly rounded and the venter is broadly rounded. swollen, weakly sinuous ribs that change Ribs are swollen, widely spaced, prorsi- from rectiradiate to prorsiradiate in an adoral radiate, and slightly sinuous on the shaft, be- direction. Umbilicolateral bullae become coming narrower, more closely spaced, more stronger and more prorsiradiate adorally and prorsiradiate, and straighter on the hook. are evenly spaced at distances of approxi- Umbilicolateral bullae are approximately 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 53 evenly spaced at distances of 3.5 mm at mid- fairly sharply rounded and the venter is ¯at. shaft. As shown on the right side, the bullae The whorl section is similar at midshaft with become more closely spaced and weaken to- a steeply convex umbilical wall. ward the aperture. On the adoral half of the The phragmocone is covered with slightly shaft and hook, there are ten very weak, ra- sinuous, prorsiradiate ribs. They are straight dial mid¯ank swellings that persist to the ap- on the outermost ¯anks where they interca- erture; they are evenly spaced on the hook at late and branch, and straight on the venter distances of 1±1.5 mm. The inner ventrolat- with approximately 11 ribs/cm. Each rib eral tubercles, of which there are 15 pre- bears a tiny outer ventrolateral tubercle. The served on the left side, are much stronger distances between tubercles at the adapical than the mid¯ank swellings. They become (broken) and adoral end of the phragmocone more closely spaced, weaker, and smaller to- are 1 and 1.5 mm, respectively. The row of ward the aperture. The distances between tu- inner ventrolateral tubercles is not as well de- bercles at midshaft and at the aperture are 5 ®ned as the row of outer ones. On the adap- and 1.5 mm, respectively. The tubercles oc- ical portion of the body chamber, ribs are cur on ribs on both the shaft and hook but slightly concave on the outer half of the the ribs tend to efface at midwhorl height on ¯anks, and they link inner and outer ventro- the shaft, giving the impression that the tu- lateral tubercles; ribs do not occur on the bercles are not linked to the ribs, although venter. Just adapical of midshaft, ribs are they retain an elongate shape. The outer ven- slightly concave on the inner ¯anks, where trolateral tubercles are similar to the inner they develop into umbilicolateral bullae, and ones and are only preserved on the adapical convex on the outer ¯anks, where they bear end of the specimen and on the hook. On the weak mid¯ank swellings. The umbilicolater- adapical end of the specimen, they are large al bullae are initially slightly arcuate and be- and widely spaced (3.5±5 mm apart) and become stronger, straighter, and more prorsira- come smaller and more closely spaced (2± diate adorally; they are evenly spaced at dis- 2.5 mm apart) on the hook. They occur on tances of 2±3 mm. Two radial mid¯ank ribs linking the inner ventrolateral tubercles. swellings occur on the adoral end of the body The distance between the umbilicolateral chamber fragment spaced 2.5 mm apart. In- bullae and the mid¯ank swellings (3.75 mm) ner ventrolateral tubercles are faint and elon- is less than that between the mid¯ank swellings and the inner ventrolateral tubercles (5 gate on the adapical part of the body cham- mm), which is greater than that between the ber but become stronger, more radial, and inner and outer ventrolateral tubercles (3.5 more widely spaced adorally, with a distance mm) (®g. 22). The distance between outer of 2.25 mm between the two most adoral tu- ventrolateral tubercles on either side of the bercles. Outer ventrolateral tubercles are pre- venter at midshaft is 6 mm. There are weak, sent on the entire piece of body chamber and straight ribs on the venter just adapical of the gradually become more widely spaced ador- aperture. ally with a distance of 2.0 mm between con- There are two other fragments of micro- secutive tubercles on the adoral end of the conchs that help to further amplify the de- specimen. On the adapical part of the body scription of the species. AMNH 47294 is part chamber, outer ventrolateral tubercles are of a phragmocone and adapical half of a linked to inner ventrolateral tubercles by body chamber (®g. 19L, M). The left side is prorsiradiate ribs, but on the adoral part, out- completely worn away. The umbilical di- er ventrolateral tubercles occur in the gaps ameter at the base of the body chamber is between inner ventrolateral tubercles. The 3.3 mm. The whorl section is compressed distance between the umbilicolateral bullae ovoid. The umbilical wall is vertical and ¯at and the mid¯ank swellings (4 mm) is equal and the umbilical shoulder is sharply round- to that between the mid¯ank swellings and ed. The inner ¯anks are broadly rounded, the the inner ventrolateral tubercles, which is mid¯anks are ¯at and subparallel, and the greater than that between the inner and outer outermost ¯anks are broadly rounded and ventrolateral tubercles (2 mm) (®g. 22). The convergent. The ventrolateral shoulder is last suture at a whorl height of 9.2 mm shows 54 AMERICAN MUSEUM NOVITATES NO. 3454 an asymmetrically bi®d ®rst lateral lobe (®g. mm) (®g. 22). The distance between outer 21B). ventrolateral tubercles on either side of the AMNH 49426 is most of the shaft of a venter at midshaft is 5.25 mm. body chamber (®g. 19X±Z, a). The umbilical DIMORPH INDETERMINATE: We describe four shoulder is curved in side view. The whorl specimens that are too fragmentary to deter- section at midshaft is subquadrate; the whorl mine the dimorph but nevertheless reveal de- width and height are 10.6 and 15.2 mm, re- tails of the ornamentation. AMNH 47298 is spectively, in intercostal section, and 11.8 part of a phragmocone with the sutures and 15.2 mm, respectively, in costal section; somewhat corroded (®g. 20A±D). The whorl the ratio of whorl width to height is 0.70 in width and height on the middle of the spec- intercostal section and 0.78 in costal section. imen are 6.7 and 9.8 mm, respectively; the The umbilical wall is steep and convex and ratio of whorl width to height is 0.68. The the umbilical shoulder is abruptly rounded. whorl section is compressed ovoid with The inner ¯anks are broadly rounded and broadly rounded ¯anks and ¯at venter. The slightly divergent, the mid¯anks are ¯at and ¯anks bear straight prorsiradiate ribs, al- gently convergent, and the outer ¯anks are though they are poorly preserved. On the broadly rounded and more steeply conver- adapical half of the specimen, the venter is gent. The ventrolateral shoulder is fairly covered with short straight ribs that disap- abruptly rounded and the venter is broadly pear adorally; there are approximately 10 rounded. ribs/cm on the venter based on the average The ¯anks are covered with slightly swol- distance between ®ve consecutive ribs. A len, weakly sinuous, prorsiradiate ribs bear- possible umbilicolateral bulla appears on the ing umbilicolateral bullae and inner ventro- adoral end of the specimen. Inner ventrolat- lateral tubercles. On the adapical half of the eral tubercles appear on the adoral one- specimen, the sinuosity of the ribs is well eighth of the specimen; the distance between expressed; the ribs are concave on the inner tubercles at the adoral end is 2.5 mm. Outer ¯anks and convex on the mid¯anks. The ribs ventrolateral tubercles are present on the en- fade out on the adoral half of the specimen, tire fragment and become progressively more but this may be due to poor preservation. The widely spaced adorally; the distances be- umbilicolateral bullae are crescentic and between tubercles on the adapical and adoral come markedly more prorsiradiate and ends are 1 and 3 mm, respectively. The tu- slightly more widely spaced adorally; the bercles are mostly paired on either side of distance between bullae at midshaft is 4 mm. the venter and are connected by short ribs on There is a row of faint mid¯ank swellings the adapical half of the specimen. The suture most of which occur on ribs on the adapical at a whorl height of approximately 12 mm is two-thirds of the specimen. The inner ven- moderately incised and shows a bi®d ®rst lat- trolateral tubercles, of which there are six eral lobe (®g. 21A). preserved on the left side, are elongated ra- AMNH 49425 is a fragment of a body dially and are approximately evenly spaced chamber with part of the ¯anks and venter at distances of 4.5 mm. There are slightly preserved (®g. 20E±H). There are some iri- fewer outer ventrolateral tubercles (®ve of descent patches on the specimen suggesting them preserved on the left side) evenly the presence of a very thin layer of shell. The spaced at distances of 4.5±5 mm with the ¯anks bear prorsiradiate, slightly swollen, exception of the two most adapical tubercles, weakly sinuous, fairly widely spaced ribs which are spaced 7.5 mm apart. The venter that terminate in fairly strong inner ventro- is smooth except for one rib near the adoral lateral tubercles, which connect in turn with end of the specimen; it is straight across the equally strong outer ventrolateral tubercles. venter. The distance between the umbilico- The tubercles in each row are spaced at dis- lateral bullae and mid¯ank swellings (4.5 tances of approximately 3±4 mm; the frag- mm) is less than that between the mid¯ank ment preserves six tubercles in each row. swellings and inner ventrolateral tubercles (5 Two narrow radial swellings occur just dorsal mm), which is greater than that between the of the inner ventrolateral tubercles on the ad- inner and outer ventrolateral tubercles (3.5 oral end of the specimen on the left side, and 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 55 a single swelling occurs in the same position is very similar to D. iris (®gs. 15A, B, G±O, on the right side. 17A±G). The main differences are (1) the AMNH 49422 is a fragment of a body ¯anks of the body chamber in D. minardi are chamber with a snail stuck in the adoral end; nearly ¯at and subparallel, whereas they are the left side of the specimen is worn away usually broadly rounded in D. iris; (2) the (®g. 20P, Q). The ornament consists of four mid¯ank swellings are weak and radial in D. rows of sharp tubercles, although the mid- minardi, if they are present at all, whereas ¯ank tubercles are elongated radially. The they are usually well developed and pointed umbilicolateral tubercles are relatively strong in D. iris; and (3) the inner ventrolateral tu- and slightly arcuate with steep adapical and bercles in D. minardi are radially elongated, more gently sloping adoral sides. They are whereas they are usually pointed in D. iris. evenly spaced at distances of 3±4 mm. The Discoscaphites minardi also resembles D. mid¯ank tubercles are weaker, thinner, and conradi in its general shape and ornament prorsiradiate; they are evenly spaced at dis- (®g. 17N±V). However, the holotype of D. tances of 3±3.5 mm. The inner ventrolateral conradi (ANSP 51551) from the Prairie tubercles are stronger and more conical than Bluff Chalk, Alabama, illustrated by Jeletzky the mid¯ank tubercles and are spaced at ap- and Waage (1978: pl. 1, ®gs. 1±4), is larger proximately equal intervals of 4.5 mm. One and covered with six rows of tubercles. Cob- of these tubercles on the adoral end sits on a ban and Kennedy (1995) characterized D. sharp prorsiradiate rib. The outer ventrolat- conradi as a highly variable species, but eral tubercles are slightly weaker than the in- none of the specimens they illustrated from ner ventrolateral ones but show the same dis- the Prairie Bluff Chalk of Alabama and Mis- tribution. The distance between the umbili- sissippi matches D. minardi. Landman and colateral bullae and mid¯ank tubercles (4.5 Waage (1993) stated that macroconchs of D. mm) is slightly less than that between the conradi usually have six to eight rows of tu- mid¯ank tubercles and the inner ventrolateral bercles and that microconchs usually have tubercles (5 mm), which is greater than that four to seven rows of tubercles; again, how- between the inner and outer ventrolateral tu- ever, none of the specimens they illustrated bercles (4 mm). The distance between ven- from the Fox Hills Formation of South Da- trolateral tubercles on either side of the ven- kota matches D. minardi. Specimens of D. ter is 5.5 mm. conradi from the Severn Formation near AMNH 47285 is the adapical half of a Brightseat, Prince Georges County, Mary- body chamber with most of the umbilical land, which is only approximately 85 km area missing (®g. 20V±Y). The whorl width from the type locality of D. minardi, also and height at midshaft are 10.7 and 14.9 mm, bear little resemblance to D. minardi (®g. respectively; the ratio of whorl width to 17N±V; Kennedy et al., 1997: ®g. 20B±J). height is 0.72. The body chamber is orna- In contrast, the specimen called D. conradi mented with slightly swollen, weakly sinu- ?conradi (Morton) (USNM 250607) ®gured ous, widely spaced ribs that become progres- by Jeletzky and Waage (1978: pl. 3, ®gs. 16, sively more prorsiradiate adorally and bear 17) from the Prairie Bluff Chalk of Alabama umbilicolateral bullae and inner ventrolateral is very similar to D. minardi. This fact sug- tubercles. The umbilicolateral bullae are gests that a bed-by-bed collection of scaphi- crescentic and are spaced at distances of 3.5 tes from the Prairie Bluff Chalk may reveal mm at midshaft. There is a suggestion of D. minardi in the upper beds. In addition, mid¯ank swellings. The inner ventrolateral Kennedy and Cobban (1993, ®g. 6g±m) doc- tubercles are approximately evenly spaced at umented specimens of D. conradi from the distances of 3.5±4 mm at midshaft. The outer Corsicana Formation of northeast Texas that ventrolateral tubercles are smaller but show are slender and some of which are close to the same distribution as the inner ventrolat- D. minardi. However, the outer ventrolateral eral tubercles, with an outer ventrolateral tu- tubercles in all of these specimens are more bercle generally occurring alongside an inner closely spaced than the inner ones, whereas ventrolateral tubercle. in D. minardi the tubercle spacing is approx- DISCUSSION: Discoscaphites minardi, n.sp. imately the same in both rows. 56 AMERICAN MUSEUM NOVITATES NO. 3454

The Kemp Clay at the top of the Corsicana responding to the upper part of calcareous Formation of northeast Texas contains Dis- nannofossil Subzone CC26a and the lower coscaphites roanensis Stephenson, 1941 part of Subzone CC26b. (Stephenson, 1941: 428, pl. 90, ®gs. 1±4), which Jeletzky and Waage (1978) synony- Discoscaphites cf. D. minardi, new species mized with D. conradi. The holotype of D. Figure 15E, F roanensis (USNM 77310), a nearly complete macroconch, is similar to D. minardi in its MATERIAL: A single specimen (USNM general form but has three rows of ¯ank tu- 525324) from the Severn Formation, Round bercles, one of which ®rst appears on the Bay, Anne Arundel County, Maryland. hook. The eight paratypes of D. roanensis DESCRIPTION: USNM 525324 is the ventral are all fragments and comprise parts of the part of a body chamber approximately 34 body chambers of three macroconchs and mm in diameter with the dorsal part still at- ®ve microconchs. USNM 77311, the ®gured tached to the matrix (®g. 15E, F). The ¯anks paratype, is part of the body chamber of a are broadly rounded to ¯at, the ventrolateral macroconch. It resembles D. minardi in the shoulder is fairly abruptly rounded, and the number of rows of tubercles, but the outer venter is broadly rounded. The ornament is ventrolateral tubercles are more closely better preserved on the left side. Broad, spaced that the inner ones. rounded, evenly spaced ribs terminate in There are several odd specimens in our elongate inner ventrolateral tubercles on the collection that we provisionally retain in D. adapical half of the specimen. These tuber- minardi. AMNH 47290 (®g. 19D±G) shows cles are much more pointed on the right side. a difference in the number of tubercle rows The distance between the two most adoral from one side of the specimen to the other. tubercles is 6.5 mm. Mid¯ank tubercles are The left side shows four rows conforming to represented by slight elevations on the broad, D. minardi, whereas the right side shows ®ve rounded ribs. A few outer ventrolateral tu- rows with the two ¯ank rows disposed on bercles are present. Both inner and outer ven- either side of midwhorl height, more closely trolateral tubercles disappear on the hook, resembling D. conradi. Supernumerary tu- which is ornamented with ®ne, straight pror- bercles occur in two other specimens. A sin- siradiate ribs. gle tubercle occurs between the inner and outer ventrolateral rows of tubercles in DISCUSSION: The presence of weak mid- AMNH 50542 (®g. 18S±U), and two very ¯ank tubercles in addition to rows of inner faint swellings occur in addition to the mid- and outer ventrolateral tubercles suggests ¯ank swellings on the right side just dorsal that this specimen is closely related to Dis- of the row of inner ventrolateral tubercles in coscaphites minardi, n.sp. However, it is too AMNH 47292 (®g. 19b±e). This variation in incomplete for positive identi®cation. tubercle number may be due to pathology or OCCURRENCE: Severn Formation, Round may indicate that the number of tubercle Bay, Anne Arundel County, Maryland. rows is not absolutely ®xed in this species. OCCURRENCE: Severn Formation, Kent Discoscaphites sp. County, Maryland; upper part of the New Egypt Formation, northeastern Monmouth MATERIAL: USNM 525331 from the Sev- County, New Jersey (Landman et al., in prep. ern Formation, Round Bay, Maryland. a). Questionable specimens of this species DESCRIPTION: USNM 525331 is the ventral have also been recovered from the top of the part of the adoral half of a body chamber (not Tinton Formation and as reworked material illustrated). It is badly worn but preserves at the base of the Hornerstown Formation rows of inner and outer ventrolateral tuber- near Freehold, central Monmouth County, cles. The tubercles in each row are widely New Jersey (Landman et al., in prep. b). This spaced at approximately equal intervals of 6± species denotes the D. minardi Zone on the 8 mm. Atlantic Coastal Plain, which represents the OCCURRENCE: Severn Formation, Round middle part of the upper Maastrichtian, cor- Bay, Anne Arundel County, Maryland. 2004 LANDMAN ET AL.: ATLANTIC COASTAL CEPHALOPODS. PART 1 57

ACKNOWLEDGMENTS ry boundary. Stockholm Contributions in Ge- ology 11(5): 103±176. We thank many people who contributed to Berggren, W.A., D.V. Kent, C.C. Swisher III, and this study: William A. Cobban (U.S. Geolog- M.-P. Aubry. 1995. A revised Cenozoic geo- ical Survey, Denver), William J. Kennedy chronology and chronostratigraphy. In W.A. (University Museum, Oxford), Herbert Klin- Berggren and J. Hardenbol (editors), Geochro- ger (South African Museum, Cape Town), nology, time scales and global stratigraphic cor- and Neal L. Larson (Black Hills Museum of relation, SEPM Special Publication 54: 130± 212. Tulsa, OK: Society for Sedimentary Ge- Natural History, Hill City, South Dakota) re- ology. viewed an early draft of this manuscript and Black, M., and B. Barnes. 1959. The structure of made many helpful suggestions; Jean Self- coccoliths from the English Chalk. Geological Trail (U.S. Geological Survey, Reston) ex- Magazine 96(5): 321±328. amined samples from Maryland and North Bramlette, M.N., and E. Martini. 1964. The great Carolina for nannofossils; W. Burleigh Harris change in calcareous nannoplankton fossils be- (University of North Carolina, Wilmington) tween the Maestrichtian and Danian. Micropa- supplied information about the Peedee For- laeontology 10: 291±322. mation; Don Clements (Rocky Point, NC) Brenner, G.J. 1992. Palynological analyses of se- and Ned Gilmore (ANSP) donated specimens lected core samples from KEN-BF 180. Mary- land Geological Survey Open-File Report 9-02- from the Peedee Formation to the AMNH; 7, appendix C: 27±30. Harry Mendryk (New York) helped in the Brouwers, E.M., and J.E. Hazel. 1978. Ostracoda ®eld, donated specimens, and freely shared and correlation of the Severn Formation (Na- his ideas; Susan Klofak (AMNH) helped in varroan; Maestrichtian) of Maryland. SEPM the ®eld, prepared specimens, and drew su- Paleontological Monograph 1: 1±52. tures; Kathy Sarg (AMNH) helped in the Brunnschweiler, R.O. 1966. Upper Cretaceous ®eld, did the sedimentological analysis, and ammonites from the Carnarvon Basin of West- helped prepare the ®gures; Bushra Hussaini ern Australia. 1. The heteromorph Lytoceratina. (AMNH) helped in the ®eld; Steve Thurston Bureau of Mineral Resources Geology and (AMNH) photographed the specimens and Geophysics Bulletin (Canberra) 58: 1±58. Bukry, D. 1969. Upper Cretaceous coccoliths helped prepare the ®gures; Colleen McCartan from Texas and Europe. The University of Kan- (U.S. Geological Survey, Reston) prepared sas Paleontological Contributions, Article the dino¯agellate samples; Dan Kuehne (de- 51(Protista 2): 1±79. ceased, Merchantville, NJ) helped in the Burnett, J.A. 1998a. Upper Cretaceous. In P.R. ®eld; and Stephanie Crooms (AMNH) word Brown (editor), Calcareous nannofossil biostra- processed the manuscript. tigraphy: 132±199. London: Chapman and Hall. REFERENCES Burnett, J.A. 1998b. New taxa and new combi- nations of Cretaceous nannofossils. Journal of Alberti, G. 1959. Zur Kenntnis der Gattung De- Nannoplankton Research 19: 133±146. ¯andrea Eisenack (Dino¯ag.) in der Kreide und Christensen, W.K. 1996. A review of the Upper im AlttertiaÈr Nord- und-Mitteldeutschland. Mit- Campanian and Maastrichtian belemnite bio- teilungen des Geologischen Staatsinstitut Ham- stratigraphy of Europe. Cretaceous Research burg: 28: 93±105. 17: 751±766. Arkhangelsky, A.D. 1912. Cretaceous deposits of Clark, W.B. 1916. The Upper Cretaceous deposits east European Russia. Materialien zur Geologie of Maryland. In W.B. Clark et al., Upper Cre- Russlands 25: 1±631. taceous. Maryland Geological Survey System- Baird, D. 1986. Upper Cretaceous reptiles from atic Report 6(1): 23±110. Baltimore: Johns the Severn Formation of Maryland. Mosasaur Hopkins University Press. 3: 63±85. Clark, W.B., R.M. Bagg, and G.B. Shattuck. 1897. Benson, D.G., Jr. 1976. Dino¯agellate taxonomy Upper Cretaceous formations of New Jersey, and biostratigraphy at the Cretaceous-Tertiary Delaware and Maryland. Geological Society of boundary, Round Bay, Maryland. Tulane Stud- America Bulletin 8: 315±358. ies in Geology and Paleontology 12(4): 169± Cobban, W.A., and W.J. Kennedy. 1992. The last 233. Western Interior Baculites from the Fox Hills Berggren, W.A. 1964. The Maestrichtian, Danian Formation of South Dakota. Journal of Pale- and Montian Stages and the Cretaceous-Tertia- ontology 66(4): 682±684. 58 AMERICAN MUSEUM NOVITATES NO. 3454

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