Upper Cretaceous molluscan record along a transect from Virden, New Mexico, to Del Rio, Texas William A. Cobban, U.S. Geological Survey, Denver Federal Center, Box 25046, M.S. 980, Denver, Colorado 80225; Stephen C. Hook, Atarque Geologic Consulting, LLC, 411 Eaton Avenue, Socorro, New Mexico 87801, [email protected]; K. C. McKinney, U.S. Geological Survey, Denver Federal Center, Box 25046, M.S. 980, Denver, Colorado 80225, [email protected]

Abstract provisional faunal zonation for this area that Regarding the last three names, Powell links it with the better known zonation for (1965, p. 511) noted that “These formations Updated age assignments and new collec- the Western Interior (Fig. 2). Late Cretaceous intertongue; they are lateral equivalents of tions of molluscan fossils from lower Cenom- ammonite faunas from southwest New Mex- each other. The separate names indicate anian through upper Campanian strata in ico have been treated recently by us (Cobban lithologic variations, that is, depositional Texas permit a much refined biostratigraphic correlation with the rocks of New Mexico and et al. 1989) and will only be reviewed herein. features due to the relative proximity of the the Western Interior. Generic names of many Many published faunal lists and age assign- Coahuila platform (Kellum et al. 1936), and Late Cretaceous ammonites and inoceramid ments for lower Cenomanian to upper Cam- to the Diablo platform (Cohee et al. 1961).” bivalves from Texas are updated to permit panian strata in Texas are updated herein. Two ammonite zones can be recognized in this correlation. W. J. Kennedy and others have updated the Del Rio Clay, a lower one of Graysonites Strata correlated in the west-to-east transect parts of the late Keith Young’s (1963) monu- adkinsi Young 1958, and an upper one of include the lower Cenomanian Beartooth mental work on Coniacian through Cam- G. wacoensis (Böse 1928). The Buda Limestone Quartzite and Sarten Sandstone of southwest panian ammonites of Texas and the Gulf contains Neophlycticeras (Neophlycticeras) texa- New Mexico, and the Eagle Mountains For- Coast. They have also revised some of the mation, Del Rio Clay, Buda Limestone, and num (Shattuck 1903) in the lower part and basal beds of the Chispa Summit, Ojinaga, and pre-Coniacian ammonites published in the N. (Budaiceras) hyatti (Shattuck 1903) in the Boquillas Formations of the Texas–Mexico bor- important papers from the 1960s of J. D. upper part. Kennedy et al. (1990) reported der area. Middle Cenomanian strata are lack- Powell and associates. the occurrence of the latter species in the ing in southwestern New Mexico but are pres- New records of Cretaceous molluscan fos- European zone of Mantelliceras dixoni of late ent in the lower parts of the Chispa Summit sils from Big Bend National Park, Texas, have early Cenomanian age in Haute Normandie, and Boquillas Formations in southwest Texas. been provided by Roger and Dee Ann Coo- France. The basal parts of the Boquillas, Chis- Upper Cenomanian and lower Turonian rocks per (Lamar University, Beaumont, Texas, and are present at many localities in New Mexico pa Summit, and Ojinaga Formations contain the University of Texas at Austin, respective- an Acompsoceras inconstans (Schlüter) fauna and Texas in the Mancos Shale and Chispa ly), James and Margaret Stevens (Terlingua, Summit, Ojinaga, and Boquillas Formations. (Fig. 2). Middle Turonian and younger rocks seem Texas), and T. M. Lehman (Texas Tech Uni- Young (1959, p. 79, 1960, p. 42) noted two to be entirely nonmarine in southwestern versity, Lubbock, Texas), who are remapping zones in rocks of Del Rio age, a lower one New Mexico, but they are marine in the Rio parts of the park. Farther eastward in Terrell, of Graysonites adkinsi Young 1958, and an Val Verde, and Kinney Counties, collections Grande area in the Chispa Summit, Ojinaga, upper one of G. lozoi Young 1958. Graysonites and Boquillas Formations. The upper part of made by Val F. Freeman (USGS retired) and lozoi is now considered a junior synonym the Chispa Summit and Boquillas contain late the late J. A. Sharps (USGS) are listed. G. wacoensis in Turonian fossils. Rocks of Coniacian and San- This paper is arranged stratigraphi- of (Böse 1928) (Kennedy; tonian age are present high in the Chispa Sum- cally from lower Cenomanian to upper Kennedy et al. 2005). In Trans-Pecos Texas, mit, Ojinaga, and Boquillas Formations, and in Campanian. Fossil data from each stage G. adkinsi has been found at the base of the the lower part of the Austin. The San Carlos, or substage are then discussed geographi- Del Rio Clay in Pecos County, and G. wacoen- Aguja, Pen, and Austin Formations contain cally, with emphasis on the Texas part of sis has been found in the upper part of the fossils of Campanian age. Del Rio in Val Verde County as well as in the Fossils representing at least 38 Upper Creta- the transect. Strata in the Texas part are ceous ammonite zones are present along the located in Trans–Pecos Texas and parts of Del Rio area in Kinney County. transect. Collections made in recent years in Val Verde and Kinney Counties. Fossil col- Other ammonites from the Del Rio Clay southwestern New Mexico and at Sierra de lections from the west end of the transect in Trans-Pecos Texas are scarce. The basal Cristo Rey just west of downtown El Paso, from Virden, New Mexico, to Chispa Sum- part of the Del Rio Clay in Val Verde Coun- Texas, have been well treated and do not need mit, Texas, tend to be clustered closely ty yielded the holotype of Mariella brazoen- revision. Taxonomic names and zonations around the locality markers because the sis pecoensis Clark 1965. Clark also recorded published in the pre-1970 literature on the Rio Upper Cretaceous outcrops in those areas M. brazoensis brazoensis from the Del Rio Grande area of Texas have been updated. New as far west as the Quitman Mountains in fossil collections from the Big Bend National are isolated remnants. Collections from the Park, Texas, allow for a much refined cor- east end of the transect, especially from Big Hudspeth County. relation in the central part of the transect in Bend National Park to Del Rio, Texas, are The Buda Limestone in Trans-Pecos Texas. widely scattered around the locality mark- Texas usually consists of a lower thick- and Middle Turonian–Campanian zonation in ers because of the more extensive outcrops thin-bedded limestone, a softer middle southwest Texas is based mainly on ammo- of Upper Cretaceous rocks in those areas. nodular limestone, and an upper thick- nites of the Family Collignoniceratidae, bedded limestone (Maxwell et al. 1967; as opposed to the scaphitid and baculitid Freeman 1968). Neophlycticeras (Neophlyc- ammonites that are especially abundant far- Cenomanian Stage ticeras) texanum (Shattuck 1903) is fairly ther north in the Western Interior. Lower Cenomanian abundant in the lowest limestone member, and N. (Budaiceras) hyatti (Shattuck 1903) Introduction Rocks of early Cenomanian age in Trans- is common in the middle and upper mem- Pecos Texas and the adjoining part of Chi- bers. The two subgenera can be told apart The purposes of this report are (1) to corre- huahua and Coahuila, Mexico, consist of the easily because Neophlycticeras has siphonal late Upper Cretaceous strata along a west- following sequence, from oldest to young- tubercles matched by the flank ribs, where- to-east transect from Virden, New Mexico, to est: Del Rio Clay (or Formation), Buda as Budaiceras has more siphonal tubercles Del Rio, Texas (Fig. 1), using ammonites and Limestone, and basal parts of the Boquillas, than flank ribs. Wright and Kennedy (1994, inoceramid bivalves, and (2) to provide a Chispa Summit, and Ojinaga Formations. p. 550) noted the close resemblance of

August 2008, Volume 30, Number 3 Ne w Me x i c o Ge o l o g y 75 Neophlycticeras and Budaiceras and stated He considered the fauna to represent a new A. renevieri (Sharpe 1857) were found nearby that the latter “could well be treated as no zone (Puchellia brundrettei) at the top of the slightly higher in the Chispa Summit. Daugh- more than a subgenus of Neophlycticeras,” lower Cenomanian. Young and Powell (1978) erty and Powell (1963, p. 2060) noted the pres- which is how we treat them in this paper. more correctly placed the species brundrettei ence of this fauna at the base of the Boquillas In addition to N. (B.) hyatti and N. (N.) tex- in the genus Forbesiceras. Hook and Cobban Formation in the Pico Etereo area of northern anum (recorded as Faraudiella texana), Young (1983, p. 51) recorded five species of ammo- Coahuila, just east of Big Bend National Park. (1979) reported Budaiceras elegantior (Lass- nites in the F. brundrettei Zone at Gold Hill in (See also Young 1969, table 1). witz 1904), B. alticarinatum n. sp., Faraud- northernmost Jeff Davis County, and Kenne- In summary, the early Cenomanian iella franciscoensis (Kellum and Mintz 1962), dy and Cobban (1993) further updated the ammonite sequence in Trans-Pecos Texas, F. roemeri (Lasswitz 1904), F. barachoensis n. fauna from six localities, which now consists from youngest to oldest, is as follows: sp., F. archerae n. sp., Mariella wysogorskii, and of the following ammonites: Moremanoceras Forbesiceras brundrettei (Young) Sharpeiceras tlahualilense (Kellum and Mintz elgini (Young 1958), Acompsoceras sp., Forbe- Acompsoceras inconstans (Schlüter) 1962) from the Buda Limestone of Trans- siceras brundrettei (Young 1958), Borissiako- Neophlycticeras (B.) hyatti (Shattuck) Pecos Texas. ceras sp., Ostlingoceras (Ostlingoceras) brandi Neophlycticeras (N.) texanum (Shattuck) Budaiceras has been reported from the (Young 1958), Mariella (Mariella) davidense Graysonites wacoensis (Böse) basal part of the Maness Shale of northeast- (Young 1958), Mariella (M.) cf. cenomanensis Graysonites adkinsi Young ern Texas (Lozo 1951, p. 81). The Maness, (Schlüter 1876), and Hypoturrilites youngi known only in the subsurface, overlies the (Clark 1965). Graysonites adkinsi was suggested as a Buda Limestone and disconformably under- The most abundant fossil in the Forbe- guide to the base of the Cenomanian Stage lies the Woodbine Formation (Bailey et al. siceras brundrettei Zone is the small species at the First International Symposium on Cre- 1945). A few fragments of ammonites from described by Young (1958) as Desmoceras taceous Stage Boundaries in Copenhagen in the Del Rio and Buda Formations at Sierra (Pseudouhligella) elgini, but now placed in 1984 (Birkelund et al. 1984, p. 11), but no fur- de Cristo Rey may represent Neophlycticeras, Moremanoceras (Kennedy et al. 1988a). Most ther action was taken. The age of this ammo- but none can be assigned to a species. specimens are a centimeter or less in diameter nite is probably equivalent to the early part Mantelliceras Hyatt 1903, an important and probably represent either juvenile indi- of the Mantelliceras mantelli Zone of England guide to the lower Cenomanian of Europe, viduals or inner whorls of larger specimens. and France (Hancock et al. 1994, table 1). has been reported from Coahuila, Trans- Powell (1965) considered them as a guide to Both the zones of Acompsoceras inconstans Pecos Texas, and southwestern New Mexico. a Pseudouhligella elgini Zone at the base of and Forbesiceras brundrettei are correlated to From the Buda Limestone of northern Coa- the Chispa Summit Formation in Jeff Davis the Mantelliceras dixoni Zone at the top of the huila, Böse (1928) described a specimen that County, Texas. The fauna has been found lower Cenomanian of Europe (Cobban and he assigned to M. mantelli (d’Orbigny 1850) as far east as Brackettville in central Kinney Kennedy 1989, p. 135; Hancock et al. 1994, as well as another specimen he described County (Kennedy and Cobban 1993). table 1). The American zones are known as the new form M. laticlavium Sharpe var. Powell (1963a) described a small, but only from Trans-Pecos Texas and northern mexicanum. The latter was considered later mostly new, ammonite fauna from a thin Coahuila, Mexico. as Sharpeiceras mexicanum (Böse) by Matsu- bed of limestone in the lower 23 m (75 ft) There appears to be a gap or two in the moto (1969, p. 259). Farther south in Coahu- of the Ojinaga Formation in the foothills Trans-Pecos Texas sequence. Freeman (1968, ila, Kellum and Mintz (1962) described two of the Quitman Mountains in Hudspeth p. K9) noted that the Buda Limestone rest- specimens as new species of Mantelliceras, County, Texas. The fauna was described as ed disconformably on the Del Rio Clay in M. charlestoni and M. portalesi, from the Buda Euhystrichoceras adkinsi n. sp., Pseudacomps- the area of the Terrell arch in eastern Ter- equivalent in the middle of the Indidura For- oceras bifurcatum n. sp., and Desmoceras rell County and western Val Verde County, Texas, and that the base of the Buda is a mation. Both specimens are now regarded (Pseudouhligella) elgini Young, and assigned conglomerate containing clasts of the Del as probably M. dixoni by Wright and Ken- to the early Cenomanian. Additional col- Rio (see also Lonsdale et al. 1955, p. 32). nedy (1984, p. 124). Adkins (1931) described lections from Powell’s locality were made Maxwell et al. (1967, p. 53) observed that the the new species M. budaense from the top of by Hook and Cobban in 1973 and by W. J. Buda rested directly on the Albian George- the Buda Limestone of Travis County east Kennedy and J. M. Hancock in 1979. These town Limestone on the Terrell arch. A hiatus of Trans-Pecos Texas. The species was con- new and larger collections were made from within the Buda is possible. In the north- sidered a synonym of M. cantianum Spath a petroliferous, sandy limestone bed 9.2 m ern part of south-central Texas, where the 1926 by Young and Powell (1978) and Young (30 ft) above the base of the Ojinaga Forma- Buda is two-fold, the top of the lower part is (1979). Wright and Kennedy (1984, p. 120) tion. The fauna consists of Moremanoceras marked by a bored surface, and some trun- noted that M. budaense is a coarsely ribbed bravoense (Cobban and Kennedy 1989) (= cation of the lower part is reported (Martin derivative of M. couloni (d’Orbigny 1850). Desmoceras elgini Young of Powell 1963a), 1967). The bases of the Boquillas, Ojinaga, Cobban and Kennedy (1989, p. 135) reported Euhystrichoceras adkinsi (Powell 1963a), Oji- and Chispa Summit Formations rest sharply the presence of Mantelliceras sp. at the top nagiceras ojinagaense Cobban and Kennedy and disconformably on the Buda Limestone 1989, Stoliczkaia (Lamnayella) chancellori of the Buda Limestone in Hudspeth Coun- (Maxwell et al. 1967, fig. 32). ty, Texas, and Hancock et al. (1994, p. 463) Wright and Kennedy 1984, Acompsoceras noted M. lymense (Spath 1926) from Brewster inconstans (Schlüter 1871) (= Pseudoacomps- County. Mantelliceras sp. also occurs at the oceras bifurcatum Powell 1963a), Hypoturri- Middle Cenomanian lites cf. gravesianus (d’Orbigny 1842), and top of the Sarten Sandstone in the Cookes Strata of middle Cenomanian age in the Inoceramus aff. I. arvanus Stephenson 1953. Range in Luna County in southwestern Western Interior of the United States con- New Mexico (Cobban 1987a). Daugherty and Powell (1963) also noted tain the following sequence of acanthocer- The calcareous Boquillas, Chispa Sum- the presence of this fauna at the base of the atid ammonites (updated from Cobban mit, and Ojinaga Formations overlie the Boquillas Formation in northern Coahuila, Buda Limestone in Trans-Pecos Texas. The Mexico, just east of Big Bend National Park 1984, fig. 2) from youngest to oldest: Boquillas, Boquillas Flags of Freeman (1968), (see also Young 1969, p. 100). Plesiacanthoceras wyomingense (Reagan) and Chispa Summit are chiefly thin-bedded The Acompsoceras inconstans Zone is also Acanthoceras amphibolum Morrow limestone and shale deposited on the Dia- known farther southeastward at the base Acanthoceras bellense Adkins blo platform, whereas the much thicker, silty of the Chispa Summit Formation at its type Plesiacanthoceras muldoonense Ojinaga was deposited as a basin facies in locality in Jeff Davis County, Texas (Kennedy (Cobban and Scott) the Chihuahua trough (Powell 1965). Young et al. 1989). Here a sandstone bed occupying Acanthoceras granerosense Cobban and Scott (1958) described a new fauna of silicified depressions in the top of the Buda Limestone Conlinoceras tarrantense (Adkins) ammonites from near the base of the Boquil- yielded part of a large ammonite that appears Kennedy et al. (1989) reported the Acan- las in Jeff Davis County in Trans-Pecos Texas. to be A. inconstans. Two specimens that may be thoceras bellense Zone at Chispa Summit in Jeff

76 Ne w Me x i c o Ge o l o g y August 2008, Volume 30, Number 3 Davis County, Texas. A thin bed of limestone The gap at the top of the Cenomanian in Cunningtoniceras cookense Cobban, Hook, 15 ft (4.6 m) above the base of the Chispa New Mexico (Fig. 2) represents the Nige- and Kennedy Summit Formation contains Acanthoceras bel- riceras scotti Zone that is missing in south- Calycoceras (Calycoceras) inflatum Cobban, lense (Adkins 1928), Paraconlinoceras leonense western New Mexico owing to an erosional Hook, and Kennedy (Adkins 1928), Acompsoceras sp., Cunning- interval. This zone has not been recorded in Calycoceras (Proeucalycoceras) guerangeri toniceras johnsonanum (Stephenson 1955), Tar- Trans-Pecos Texas. (Spath) rantoceras sp., Turrilites acutus (Passy 1832), Calycoceras canitaurinum (Haas 1949) was Calycoceras (Proeucalycoceras) sp. nov. Inoceramus aff. arvanus Stephenson 1953, and chosen as the zonal name because of its Calycoceras (Proeucalycoceras) sp. Ostrea beloiti Logan 1899. The oyster Ostrea Eucalycoceras pentagonum wide distribution in the Western Interior. (Jukes-Browne) beloiti is known from the lower Cenomanian Euomphaloceras euomphalum (Sharpe) The zone of Calycoceras canitaurinum is well zone of Forbesiceras brundrettei through the Euomphaloceras merewetheri Cobban, Hook, developed in the Cookes Range in Luna middle Cenomanian zone of Acanthoceras and Kennedy amphibolum in Trans-Pecos Texas (Cobban County, New Mexico, where Cobban et al. Metoicoceras mosbyense Cobban and Hook 1980; Hook and Cobban 1983; (1989) described the following ammonites Metoicoceras frontierense Cobban Kennedy et al. 1989). from the basal part of the flag member of Nannometoicoceras cf. acceleratum (Hyatt) The zone of Acanthoceras amphibolum the Mancos Shale: Vascoceras diartianum (d’Orbigny) has been recorded from Trans-Pecos Texas. Borissiakoceras sp. Hamites cf. simplex d’Orbigny The best record is from a calcarenitic lime- Moremanoceras costatum Cobban, Hook, Hamites salebrosus Cobban, Hook, and stone at the base of the Boquillas Forma- and Kennedy Kennedy tion at Sierra de Cristo Rey in Doña Ana Cunningtoniceras arizonense Kirkland and Metaptychoceras hidalgoense Cobban, County, New Mexico, just west of El Paso, Cobban Hook, and Kennedy Texas, where the Boquillas rests discon- Calycoceras (Proeucalycoceras) canitaurinum Neostlingoceras procerum Cobban, Hook, formably on the Buda Limestone (Lovejoy (Haas) and Kennedy 1976). Here, the following molluscan fauna Tarrantoceras cf. sellardsi (Adkins) Neostlingoceras virdenense Cobban, Hook, was collected (updated from Kennedy Tarrantoceras sp. and Kennedy et al. 1988a; Cobban and Kennedy 1994): Metoicoceras praecox Haas There are no records of Metoicoceras mos- Pseudocenoceras largilliertianum (d’Orbigny Metoicoceras frontierense Cobban byense in Trans-Pecos Texas or in the adjoin- 1840), Acanthoceras amphibolum Morrow Hamites cf. simplex (d’Orbigny) ing part of Mexico. Strata of that age may 1935, Moremanoceras straini (Kennedy et al. Hamites cimarronensis (Kauffman and be present in the upper 35 ft (11 m) of the 1988a), Desmoceras (Pseudouhligella) sp., Powell) flag member of the Boquillas at Gold Hill Cunningtoniceras cf. johnsonanum (Stephen- Hamites? sp. in Jeff Davis County that has not yielded son 1955), Paracompsoceras landisi (Cobban Turrilites sp. 1972), Tarrantoceras sellardsi (Adkins 1928), Turrilicone indet. diagnostic fossils (Hook and Cobban 1983). Anisoceras cf. plicatile (Sowerby 1819), Tur- Neostlingoceras kottlowskii Cobban and Likewise, the 56 ft (17 m) “barren interval” rilites (Turrilites) acutus (Passy 1832), Ostrea Hook of the Chispa Summit Formation at Chispa beloiti Logan 1899, and Inoceramus arvanus Neostlingoceras bayardense Cobban, Hook, Summit (Kennedy et al. 1989, fig. 2) might Stephenson 1953. and Kennedy contain rocks of mosbyense age. The pres- The Acanthoceras amphibolum Zone is ence of Inoceramus ginterensis Pergament in present 6–12 ft (2–4 m) above the base of This is the largest and most diverse ammo- Big Bend National Park suggests the zone of the Boquillas Formation at Gold Hill in Jeff nite fauna of the C. canitaurinum Zone known Metoicoceras mosbyense. Davis County, Texas (Fig. 1). There the lower from North America. A new species, More- The straight ammonite Sciponoceras gracile Cenomanian fauna of Forbesiceras brundrettei manoceras montanaense Kennedy and Cobban (Shumard 1860) is an excellent guide fossil is at the base of the formation. Molluscan 1990a, was also found in the equivalent part to the upper one-half of the upper Cenoma- fossils of the A. amphibolum Zone (Hook of the Mancos Shale farther west at Virden. nian. It is especially abundant in the lower and Cobban 1983) include Hamites simplex In Trans-Pecos Texas Calycoceras canitau- part of its range, where it is associated with (d’Orbigny 1842), Acanthoceras sp., Pseudoca- rinum was found in a thin bed of limestone the large and diverse molluscan fauna long lycoceras cf. P. harpex (Stoliczka 1865), Inocer- 55 ft (16.8 m) above the base of the Chispa known as the Euomphaloceras septemseria- amus arvanus Stephenson, I. rutherfordi (War- Summit Formation at Chispa Summit (Ken- tum Zone. Calcareous concretions in the ren 1930), and Ostrea beloiti Logan. At Gold nedy et al. 1989, p. 45). At Gold Hill in Jeff Bridge Creek Limestone Member of the Hill, a lower zone of Inoceramus arvanus Davis County, Hook and Cobban (1983, Mancos Shale in the Cookes Range and Big I. rutherfordi and an upper zone of are pres- pp. 51, 52) recorded Calycoceras cf. canitau- Burro Mountains of southwest New Mexi- ent in the ammonite zone of A. amphibolum rinum in a thin bed of limestone 20 ft (6 m) co yielded the following ammonites of the (Hook and Cobban 1983, p. 51, fig. 27). The above the base of the Boquillas Formation. zone (Cobban et al. 1989): ammonite zones of Conlinoceras tarrantense, Metoicoceras mosbyense Cobban 1953a Acanthoceras granerosense, Plesiacanthoceras Moremanoceras scotti (Moreman) was selected as the main guide to an upper muldoonense, and P. wyomingense have not Placenticeras (Karamaites) cumminsi been recognized in Trans-Pecos Texas, in Cenomanian zone owing to its wide distri- Cragin southern New Mexico, nor in Coahuila. bution in the Western Interior from north- Calycoceras (Calycoceras) naviculare ern Montana to southwest New Mexico. The (Mantell) zone is best developed and most diverse in Upper Cenomanian Pseudocalycoceras angolaense (Spath) the flag member of the Mancos Shale in the Sumitomoceras bentonianum (Cragin) The following ammonite zonation for rocks area from the Cookes Range northwest- Sumitomoceras conlini Wright and Kennedy of late Cenomanian age is recommended for ward to the Virden area in southwest New Euomphaloceras septemseriatum (Cragin) southwestern New Mexico from youngest Mexico, where the following ammonites Metoicoceras geslinianum (d’Orbigny) to oldest: have been described and illustrated (Cob- Vascoceras diartianum (d’Orbigny) Neocardioceras juddii (Barrois and de Guerne) ban et al. 1989): Allocrioceras annulatum (Shumard) Burroceras clydense Cobban, Hook, and Moremanoceras scotti (Moreman) Neostlingoceras apiculatum Cobban, Hook, Kennedy Moremanoceras sp. nov. and Kennedy Euomphaloceras septemseriatum (Cragin) Placenticeras sp. Sciponoceras gracile (Shumard) Vascoceras diartianum (d’Orbigny) Forbesiceras sp. Worthoceras vermiculus (Shumard) Metoicoceras mosbyense Cobban Cunningtoniceras novimexicanum Cobban, Metoicoceras geslinianum has been applied Calycoceras canitaurinum (Haas) Hook, and Kennedy to a Cenomanian zone in Europe at least for

August 2008, Volume 30, Number 3 Ne w Me x i c o Ge o l o g y 77 the last 25 yrs (Wright and Kennedy 1981), The zone of E. septemseriatum is present in Vascoceras cf. gamai Choffat and Euomphaloceras septemseriatum has been Coahuila, Mexico, where Jones (1938) described Vascoceras silvanense Choffat applied to a subzone in the Sciponoceras as a new species Metoicoceras bosei from the Indi- Vascoceras sp. B gracile Zone in the Western Interior (Cob- dura Formation. His holotype, the only figured Vascoceras barcoicense exile Cobban, Hook, ban 1984). Sciponoceras gracile is no longer specimen, appears to be a microconch of M. and Kennedy used as a zonal index species. Cobban et al. geslinianum. Likewise, the fragment from the Vascoceras hartti (Hyatt) (1989, p. 63) showed that S. gracile ranged Davis Mountains in Jeff Davis County illustrat- Fagesia catinus (Mantell) from the E. septemseriatum subzone through ed by Young (1959) as Metoicoceras sp. cf. bosei Rubroceras alatum Cobban, Hook, and the Neocardioceras juddii Zone. Therefore, appears to be a microconch of M. geslinianum. Kennedy Euomphaloceras septemseriatum is now used Wright and Kennedy (1981) regarded M. bosei Rubroceras burroense Cobban, Hook, and as the zonal index species (Fig. 2). as a synonym of M. geslinianum as well as the Kennedy In contrast to the large ammonite fauna specimen figured as M. aff. whitei Hyatt from Rubroceras rotundum Cobban, Hook, and of southwestern New Mexico, records Mexico by Böse (1920). Kennedy of the Euomphaloceras septemseriatum Ammonites from the Mancos Shale just Hamites cf. simplex d’Orbigny Zone are sparse farther southeastward above the zone of Sciponoceras gracile in the Big Anisoceras coloradoense Cobban, Hook, in Trans-Pecos Texas and in the adjacent Burro Mountains in Grant County, New Mexi- and Kennedy part of Mexico. The first record from that co, were assigned to the new zone of Burroceras Sciponoceras gracile (Shumard) part of Texas is probably that of Adkins clydense by Cobban et al. (1989) who described Worthoceras sp. nov. (1931, p. 67, pl. 11, figs. 7, 9) who briefly and illustrated the following species: An ammonite described as Microsulcatoceras described a small ammonite as Kanabic- sp.? by Kennedy and Cobban (1990a) from eras septemseriatum (Cragin) from Chispa Placenticeras (Karamaites) cumminsi Cragin Burroceras clydense Cobban, Hook, and Kennedy this zone in Hidalgo County, New Mexico, Summit, but in a footnote, he referred can be added to this list. the genus to Neocardioceras Spath 1926. Paraburroceras minutum Cobban, Hook, and Kennedy In Trans-Pecos Texas, the N. juddii fauna Powell (1963a) figured Adkins’ speci- was described and illustrated by Ken- men and reassigned it to Kanabiceras. Vascoceras cf. gamai Choffat Vascoceras sp. A nedy et al. (1989) from a bed of limestone That genus was considered later as a approximately 40 ft (12 m) above the base synonym of Euomphaloceras by Wright Vascoceras sp. B Vascoceras barcoicense exile Cobban, Hook, of the Chispa Summit Formation at Chispa and Kennedy (1981, p. 54). Adkins (1931) Summit. The fauna includes several species also figured ammonites as Scaphites sp. and Kennedy not recorded from the Cookes Range: aff. S. africanus Pervinquiere and Alloc- Microdiphasoceras novimexicanum Cobban, rioceras n. sp. aff. ellipticum Mantell from Hook, and Kennedy Thomelites robustus Kennedy, Cobban, the Chispa Summit Formation. These Hamites pygmaeus Cobban, Hook, Hancock, and Hook specimens were reillustrated by Kenne- and Kennedy Neocardioceras juddii (Barrois and de Guerne) dy et al. (1989, text fig. 10) and assigned Sciponoceras gracile (Shumard) Pseudaspidoceras pseudonodosoides (Choffat) to Worthoceras vermiculus (Shumard) and Worthoceras vermiculus (Shumard) Nigericeras gadeni (Chudeau) Allocrioceras annulatum (Shumard). In This fauna has not been found elsewhere Thomelites kaulabicus (Kler) the Chispa Summit Formation at Chis- along the Virden–Del Rio transect. Thomelites sp. pa Summit, Powell (1965, p. 517) noted The youngest Cenomanian ammonite fauna Thomelites sp.? a “Zone of Kanabiceras septemseriatum” known from the Virden–Del Rio transect lies Vascoceras (V.) silvanense Choffat containing the guide fossil and the spe- in the Neocardioceras juddii Zone. The zonal Vascoceras (V.) cauvini Chudeau cies Watinoceras sp. cf. W. coloradoense guide fossil, described as Ammonites juddii by (Henderson) and Metoicoceras sp. Barrois and de Guerne (1878) from France, is Turonian Stage From chalky limestone beds 120–126 ft widely distributed in Europe at the top of the (36.5–38.5 m) above the base of the Chis- Cenomanian and designated the Neocardio- Lower Turonian pa Summit Formation at Chispa Summit, ceras juddii Zone (Wright and Kennedy 1981). The lower Turonian ammonite zonation Kennedy et al. (1989, p. 45) reported the This zone was first applied in the Western following ammonites: Interior by Hook and Cobban (1981). in the Western Interior has been based Moremanoceras scotti (Moreman) Ammonites of the Neocardioceras juddii mainly on the Bridge Creek Member of the Calycoceras (C.) naviculare (Mantell) Zone attain their greatest variety at the top Greenhorn Limestone in the Pueblo area of Euomphaloceras septemseriatum (Cragin) of the Bridge Creek Limestone Member of south-central Colorado, where the follow- Pseudocalycoceras angolaense (Spath) the Mancos Shale in the Cookes Range and ing sequence has been determined: Metoicoceras geslinianum (d’Orbigny) in the equivalent shale member farther west Mammites nodosoides (Schlüter) Borissiakoceras reesidei Morrow in southwestern New Mexico, where the fol- Vascoceras birchbyi Cobban and Scott Sciponoceras gracile (Shumard) lowing species were described and illustrated Pseudaspidoceras flexuosum Powell Worthoceras vermiculus (Shumard) (Cobban et al. 1989): Watinoceras devonense Wright and Kennedy Strata of this age are present near the Placenticeras (Karamaites) cumminsi Cragin Watinoceras devonense, at the base of the Del Rio end of the transect. Freeman (1968) Neocardioceras juddii (Barrois and de sequence, was described first by Wright and recognized the following four lithologic Guerne) Kennedy (1981) from the base of the Middle units of his calcareous Boquillas Flags Neocardioceras woodwardi Cobban, Hook, Chalk of England. The species occurs in the unit in his geologic investigation of parts and Kennedy Pueblo area in a bed of limestone 14.5 ft (4.4 m) of Brewster, Terrell, and Val Verde Coun- Ammonite indet. (gen. nov.?) above the base of the Bridge Creek Member ties: (1) a basal pinch and swell unit, (2) a Watinoceras odonnelli Cobban, Hook, and (Cobban and Scott 1973, p. 23, bed 86). This flagstone unit, (3) a ledgy limestone unit, Kennedy bed has been selected as the Global Boundary and (4) a laminated unit. Ammonites from Euomphaloceras costatum Cobban, Hook, Stratotype Point for the base of the Turonian the lower part of his ledgy unit (approxi- and Kennedy Stage (Kennedy et al. 2000, 2005). Vascoceras mately 110 ft or 33.5 m above the base of Euomphaloceras sp. birchbyi Cobban and Scott is abundant and Boquillas) include Metoicoceras geslinianum Burroceras irregulare Cobban, Hook, and restricted near Pueblo to a bed of limestone (d’Orbigny), Pseudocalycoceras angolaense Kennedy 19.8 ft (6 m) above the base of the Bridge (Spath), and Tarrantoceras (Sumitomoceras) Burroceras transitorium Cobban, Hook, and Creek Member that contains the most diverse conlini Kennedy, all restricted to the zone Kennedy ammonite fauna (eight species) of the mem- of Euomphaloceras septemseriatum. Pseudaspidoceras pseudonodosoides (Choffat) ber in Colorado. Mammites nodosoides was

78 Ne w Me x i c o Ge o l o g y August 2008, Volume 30, Number 3 described as Ammonites nodosoides by Schlüt- Powell (1963a) Chancellor (1982) and The holotype of Morrowites depressus (Mam- er (1871) from the lower Turonian of Czecho- Kennedy et al. (1987) mites? depressus Powell 1963b, p. 1228) is slovakia. The species is widely distributed in a weathered specimen from the Ojinaga Europe, Africa, South America, Mexico, and Mammites nodosoides Mammites powelli Formation at Cannonball Hill in northern (Schlüter) Kennedy, Wright, and United States. In the Pueblo area, the species Hancock Chihuahua a mile southwest of the inter- is present from 22 to 32 ft (7–10 m) above the national boundary. In a later paper, Powell base of the Bridge Creek Member. Pseudaspidoceras Pseudaspidoceras (1967) described additional material from The Watinoceras devonense Zone has not flexuosum Powell flexuosum Powell the Boquillas Formation at Gold Hill in Jeff been recorded along the Virden–Del Rio Acanthoceras Kamerunoceras Davis County, where he assigned the species transect, and the Vascoceras birchbyi Zone is calvertense Powell calvertense (Powell) to the middle Turonian. Collections from the poorly known only from the Mancos Shale Greenhorn Limestone near Pueblo, Colorado above the Bridge Creek Limestone Member Acanthoceras sp. Kamerunoceras (Cobban 1985, fig. 1), reveal that M. depressus in the Cookes Range and areas farther west. calvertense (Powell) has a short range that straddles the lower– Cobban et al. (1989) list the following ammo- Fagesia haarmanni Böse Fagesia catinus (Mantell) middle Turonian boundary. The follow- nites from the V. birchbyi Zone in the Little ing well-preserved and varied ammonite Pachyvascoceras Burro Mountains and Fort Bayard area: Vascoceras proprium fauna of latest nodosoides age that includes compressum Reyment (Reyment) Watinoceras sp. M. depressus was described from the Man- Nigericeras cf. scotti Cobban Vascoceras globosum Vascoceras proprium cos Shale from the Fence Lake area of west- Vascoceras birchbyi Cobban and Scott Reyment (Reyment) central New Mexico about 140 mi (225 km) Vascoceras sp. north of Virden (Cobban and Hook 1983). Fagesia catinus (Mantell) Allocrioceras sp. Allocrioceras larvatum Tragodesmoceras socorroense Cobban and Fagesia sp. (Conrad) Hook Neoptychites cephalotus (Courtiller) Quitmaniceras reaseri Quitmaniceras reaseri Placenticeras cumminsi Cragin Thomasites adkinsi (Kummel and Decker) Powell Powell Mammites nodosoides (Schlüter) In the Mancos Shale below the V. birchbyi Morrowites subdepressus Cobban and Hook Zone in the Cookes Range are the following Quitmaniceras brandi Quitmaniceras reaseri Powell Powell M. depressus (Powell) ammonites assigned to a Pseudaspidoceras Kamerunoceras turoniense (d’Orbigny) flexuosum Zone (Cobban et al. 1989): Kennedy et al. (1987) figured the following Neoptychites cephalotus (Courtiller) Watinoceras sp. additional ammonites of the P. flexuosum Fagesia superstes (Kossmat) Quitmaniceras reaseri Powell Zone: Cibolaites molenaari Cobban and Hook Pseudaspidoceras flexuosum Powell Neoptychites sp. Cibolaites molenaari seems to be the immediate Vascoceras sp. Wrightoceras munieri (Pervinquiere) ancestor of the middle Turonian Collignonic- Fagesia catinus (Mantell) Thomasites adkinsi (Kummel and Decker) eras woollgari (Mantell). Pseudaspidoceras flexuosum was described Allocrioceras dentonense Moreman Wright and Kennedy (1981) described by Powell (1963a) from the Ojinaga For- Sciponoceras sp. the subspecies Watinoceras coloradoense mation in Chihuahua, Mexico, and given Worthoceras cf. vermiculus (Shumard) praecursor from the Middle Chalk of Eng- zonal rank by him in 1965. A single well- Thomasites adkinsi was described as Hopli- land and recognized the zones of W. colo- preserved adult specimen of P. flexuosum toides adkinsi by Kummel and Decker (1954) radoense and Mammites nodosoides in the was found in the Vascoceras birchbyi bed from Loma el Macho, Coahuila. A new Watinoceras in the Greenhorn Limestone near Pueblo. lower part of the Turonian. genus and species, Rhamphidoceras saxatilis The specimen, described as Ampakabites coloradoense coloradoense (Henderson 1908) Kennedy and Cobban 1990b from the Chis- collignoni Cobban and Scott 1973, was later has not been recognized in England, and determined as P. flexuosum by Kennedy pa Summit Formation in Hudspeth County, the slightly older W. devonense Wright et al. (1987, p. 34). The specimen could be Texas, is the 14th ammonite genus known and Kennedy 1981 has been applied to a interpreted as being from the top of the from the P. flexuosum Zone. zone in Europe and in the Western Inte- range of P. flexuosum. The species is widely The Mammites nodosoides Zone of latest rior (Hancock et al. 1994, table 3). These distributed in the southern part of the West- early Turonian age is poorly represented authors replaced Vascoceras birchbyi by ern Interior, Trans-Pecos Texas, and north- along the Virden–Del Rio transect. In the W. coloradoense as a lower Turonian zone ern Mexico, and even as far away as Japan, western part of the transect, the zone is pres- in the Western Interior sequence because where the species marks the basal Turonian ent in the uppermost marine sandstone bed the latter “has a similar range and a much zone (Matsumoto et al. 1991, table 2; Hira- in the sandstone and shale member of the wider geographical distribution” (p. 457). no et al. 1992, table 2). Mancos Shale in the Cookes Range, where In the present report, V. birchbyi is retained The holotype of P. flexuosum came from a the following ammonites were described as the zonal index (Fig. 2). bed of crystalline limestone 990 ft (302 m) (Cobban et al. 1989): Gale (1996, p. 181) reviewed the Turo- above the base of the Ojinaga Formation Watinoceras sp. nian ammonite zonation of southern Eng- about a mile south of the Kelsey Crossing Mammites nodosoides (Schlüter) land, introduced the new zone of Fagesia on the Rio Grande in northeastern Chihua- Infabricaticeras lunaense Cobban, Hook, catinus (Mantell 1822) between the zones of hua, Mexico (Powell 1961, fig. 1). A large and Kennedy W. devonense and M. nodosoides, and noted and diverse ammonite fauna is present in Thomasites? sp. that the F. catinus Zone was about equivalent the bed of limestone on both sides of the In Trans-Pecos Texas, M. nodosoides has been to the zones of Pseudaspidoceras flexuosum international border as well as farther east in recorded from 79 to 116 ft (24–35 m) above and Vascoceras birchbyi of the Western Inte- Coahuila. Powell (1963a) described 11 spe- cies in eight genera. Some ammonites of this the base of the Boquillas Limestone at Gold rior. Fagesia catinus occurs in the latter two fauna (P. flexuosum Zone) had been described Hill in Jeff Davis County, Texas, where the zones, and the species is especially abundant earlier by Böse (1920) from Coahuila. The following species were found (Hook and in the zone of P. flexuosum in Trans-Pecos fauna in Coahuila was further investigated Cobban 1983): Texas and adjoining part of Mexico. These by Chancellor et al. (1977) and Chancellor Mammites nodosoides (Schlüter) two zones are closely related timewise and (1982) and in Chihuahua and Trans-Pecos Morrowites depressus (Powell) have several ammonite species in common. Texas (Hudspeth County) by Kennedy et al. Kamerunoceras turoniense (d’Orbigny) Perhaps F. catinus could be treated in North (1987). Their revision of Powell’s identifica- Hoplitoides sp. America as a zone with P. flexuosum and tions is as follows: Fagesia? sp. V. birchbyi as subzones.

August 2008, Volume 30, Number 3 Ne w Me x i c o Ge o l o g y 79 Middle Turonian Virden–Cookes Range area in southwest- Trans-Pecos Texas, and the adjoining part of ern New Mexico (Cobban et al. 1994, fig. 5), Chihuahua, see Kennedy et al. (1977), and Before 1979 Turonian rocks in the Western so that rocks of this age in that area are non- for the shoreline during hyatti time, see Cob- Interior were not divided into lower, middle, marine. The species does occur, however, in ban et al. (1994, fig. 6). and upper parts. At that time, a middle Turo- Trans-Pecos Texas, in the upper part of the The Prionotropis eaglensis Adkins 1928 nian substage was recognized in the United Chispa Summit Formation near Chispa Sum- (p. 250) from the base of the Eagle Moun- States that is divisible into two ammonite mit (Kennedy et al. 1989), where C. woollgari tains in Hudspeth County, Texas, is a zones, a lower Collignoniceras woollgari Zone regulare (Haas 1946) occurs with Tragodesmo- Prionocyclus hyatti as noted by Powell and an upper Prionocyclus hyatti Zone (Kauff- ceras socorroense Cobban and Hook, Romanic- (1963b, p. 1220). Prionocyclus hyatti also man et al. 1978, p. 23. 16). The woollgari Zone occurs in northeastern Chihuahua (Powell was subdivided into a lower woollgari wooll- eras (Yubariceras) ornatissimum (Stoliczka), 1965, fig. 6). Kennedy and Cobban (1988) gari Subzone and an upper woollgari regulare and Spathites coahuilaensis (Jones). The last described the following new additions to Subzone by Cobban and Hook (1979, fig. 1). species is known also from Coahuila and hyatti Puzosia A zone of Prionocyclus percarinatus was recog- Chihuahua, where the species was described the fauna from Chihuahua: nized later between the woollgari and hyatti under several names by Jones (1938), Kum- (P. ) serratocarinata Kennedy and Cobban, Zones, and the hyatti Zone was divided into mel and Decker (1954), and Kennedy et al. Romaniceras (Yubariceras) kanei Jones, and Hoplitoides sandovalensis and Coilopoceras (1980) (see Cobban 1988a, p. 8; Kennedy Romaniceras (R.) reymenti (Collignon). springeri Subzones (Cobban and Hook 1983, et al. 1989, p. 77). There is also a record of Cooper et al. (2008, p. 28, fig. 35) report fig. 1). The poorly defined P. percarinatus C. woollgari from the Big Bend National Park P. hyatti and Inoceramus howelli White from (Hall and Meek 1856) was replaced later (Bell 1994), and the species has been found a thin bed of limestone in the Ernst Member (Merewether et al. 1998, fig. 2) by the much as far east as south-central Kinney County, of the Boquillas Formation in the southern better defined Collignoniceras praecox (Haas Texas (USGS locality D2464). part of Big Bend National Park. 1946). Another change in the middle Turo- At Gold Hill, Jeff Davis County, Texas, Rocks of the age of the Prionocyclus nian zonation in the paper by Merewether et C. woollgari woollgari (Mantell) occurs macombi and P. wyomingensis Zones are al. (1998, fig. 2) is a shift in the middle–upper approximately 144 ft (44 m) above the base of probably nonmarine west of El Paso, and Turonian boundary upward to the base of the Boquillas Limestone (Hook and Cobban records of these zones farther southeast are the Scaphites whitfieldi Zone based on work 1983) associated with Spathites rioensis Pow- sparse. Hook and Cobban (1983) reported in progress at that time on Turonian and ell and Neoptychites sp. Collignoniceras wooll- the presence of the small bivalve Nicaiso- Coniacian inoceramid faunas by Ireneusz gari has been described also as Prionotropis lopha lugubris (Conrad) in the upper part Walaszczyk (Institute of Geology, University woollgari (Mantell) var. mexicana Böse 1928 of the shale and limestone member of the of Warsaw, Poland). He found that Inocera- from near Villa Acuña, Coahuila, across the Boquillas Limestone at Gold Hill in Jeff mus costellatus Woods 1912 of most authors, Rio Grande from Del Rio, and Powell (1963b) Davis County, Texas. That fossil is common and long regarded as the main guide to the noted its occurrence in the Ojinaga Forma- in the zones of P. macombi and P. wyomin- base of the upper Turonian of Europe, is the tion at Cannonball Hill, Chihuahua. Other gense in the Juana Lopez Member of the same species as I. perplexus Whitfield (1877, ammonites from the C. woollgari woollgari Mancos Shale in northern New Mexico. 1880), a common species restricted to the Subzone at Cannonball Hill were reported Kennedy et al. (1989, fig. 3) listed the fol- Scaphites whitfieldi Zone in the middle of the by Kennedy and Cobban (1988) as follows: lowing species from a bed of limestone high upper Turonian of the Western Interior (for Morrowites depressus (Powell), Morrowites sp., in the Chispa Summit Formation at Chispa discussion, see Walaszczyk and Cobban 2000, Spathites (S.) rioensis (Powell), Neoptychites Summit and assigned them to the Scaphi- p. 34). The middle Turonian ammonite zona- cephalotus (Courtiller), Kamerunoceras iso- tes warreni Subzone of the P. wyomingensis tion in the Western Interior now consists of vokyense (Collignon), Hoplitoides ingens (von Zone: P. wyomingensis Meek, Hourcquia cf. the following sequence modified from Cob- Koenen), and Baculites yokoyamai Tokunaga mirabilis Collignon, Coilopoceras inflatum ban (1984, fig. 2). and Shimizu. Kennedy and Cobban (1988) Cobban and Hook, Baculites yokoyamai also noted the presence of Hoplitoides cf. gib- Tokunaga and Shimizu, and Inoceramus Zone Subzone bulosus (von Koenen) in the C. woollgari Zone dimidius White. For further information on Scaphites ferronensis in Chihuahua. the occurrence of Hourcquia at Chispa Sum- Scaphites warreni The zone of Collignoniceras praecox has not mit, see Kennedy et al. (1988b, p. 92). Prionocyclus Coilopoceras inflatum been reported from the area of the Virden–Del macombi Coilopoceras colleti Rio transect, but the slightly younger Priono- Upper Turonian cyclus hyatti Zone is known from Trans-Pecos, Prionocyclus hyatti Coilopoceras springeri Texas. At Chispa Summit, P. hyatti (Stanton) Records of late Turonian fossils are few Hoplitoides sandovalensis occurs in septarian limestone concretions in along the Virden–Del Rio transect and con- Collignoniceras the upper part of the Chispa Summit For- fined to Trans-Pecos Texas. Kennedy et al. praecox mation approximately 130–165 ft (40–50 m) (1989, fig. 3) reported Inoceramus perplexus from a bed of limestone high in the Chis- Collignoniceras Collignoniceras woollgari above concretions that contain C. woollgari woollgari regulare regulare (Kennedy et al. 1989, fig. 3; Powell pa Summit Formation at Chispa Summit Collignoniceras woollgari 1965, fig. 4). Other ammonites from the hyatti approximately 2 m (6.5 ft) above a bed con- woollgari concretions include Romaniceras (R.) mexica- taining I. dimidius of middle Turonian age. They also reported I. perplexus and Prionocy- Collignoniceras woollgari (Mantell 1822) has num Jones, Spathites puercoensis (Herrick and Johnson), Coilopoceras springeri Hyatt, and clus novimexicanus (Marcou) approximately long been accepted informally by authors Scaphites carlilensis Morrow. A most interest- 22 m (72 ft) above the I. dimidius bed. This as a guide to the base of the middle Turo- ing and unusual bed of limestone contain- last occurrence indicates the Prionocyclus nian; however, more recently, bed 120, a ing C. woollgari woollgari occurs in the upper novimexicanus Zone. limestone high in the Bridge Creek Member part of the Boquillas Limestone at Gold Hill Young (1963) described Prionocycloceras of the Greenhorn Limestone near Pueblo, (Hook and Cobban 1983, bed 20, p. 49). adkinsae as a new species from the upper Colorado, containing the first occurrence of The bed, approximately 6 inches (15 cm) part of the Chispa Summit Formation near C. woollgari was suggested, but not accepted, thick, contains well-preserved specimens of Chispa Summit, and also noted its presence as the base of the middle Turonian substage P. hyatti and phosphatic pebbles and cobbles in Presidio County. His illustrated speci- (Kennedy et al. 2000, fig. 5). made from worn fragments of C. woollgari mens are herein interpreted as the robust The western shoreline during the time and other ammonites of woollgari age. For form of Prionocyclus wyomingensis Meek of Collignoniceras woollgari was east of the a discussion on other hiatus concretions in (compare to Kennedy et al. 2001, fig. 85).

80 Ne w Me x i c o Ge o l o g y August 2008, Volume 30, Number 3 As noted earlier in the treatment of the A conspicuous ledge-forming unit a few Substage Ammonite zone upper Cenomanian, Freeman (1961, 1968) feet thick consisting of flaggy limestone with subdivided his Boquillas Flags into four infor- upper shale partings is present approximately 330 ft Prionocycloceras gabrielense mal lithologic units in Val Verde and Terrell (100 m) above the base of the Ernst Member Coniacian Counties, Texas. The uppermost unit, “lami- of the Boquillas Formation in the Big Bend Peroniceras westphalicum nated unit,” contains Inoceramus cf. dimidius area of Texas (Maxwell et al. 1967) The unit lower Coniacian White 10 ft (3 m) above the base, which sug- is characterized by the uncoiled planispiral Peroniceras haasi gests a high position in the middle Turonian ammonite Allocrioceras hazzardi Young (1963), (Freeman 1961, table 1). Near the top of the The holotype of Peroniceras haasi Young (1963, and the unit is “commonly termed the ‘Crio- p. 72) came from the Austin Chalk of east- unit, Freeman listed I. cf. perplexus Whitfield ceras’ ledge or ‘Crioceras’ zone” (Young 1963, and Prionocyclus sp., which suggests a low central Texas, but Young recorded the spe- p. 45). Young assigned a late Turonian age to position in the upper Turonian. Chalky lime- cies farther southwest in Uvalde and Kinney A. hazzardi. A few fragments of Allocrioceras stone overlying the Boquillas was referred to Counties. Young did not recognize a middle the Austin Chalk by Freeman, who listed Pri- from Wyoming, Colorado, and Utah, associ- Coniacian, but the species P. westphalicum onocyclus reesidei Sidwell 1932 and Inoceramus ated with early Coniacian molluscan fossils, (von Strombeck 1859) is confined to that sub- stage according to Kennedy (1984, p. 74). cf. incertus Jimbo in the lower 35 ft (10 m). The were assigned to A. hazzardi by Kennedy and P. reesidei is now considered a junior synonym Cobban (1991a). A small collection made by Prionocycloceras gabrielense Young (1963, of P. germari Reuss 1845 (Kennedy et al. 2001, V. L. Freeman (unpublished, USGS Mesozoic p. 69–71) is a problematic species as noted by p. 127), and the inoceramid is now assigned locality D2874) from the A. hazzardi bed at Del Young, who assigned it to the upper Conia- to Mytiloides. Freeman (unpublished) also Norte Gap in the Big Bend area of Texas con- cian. Matsumoto (1965a, p. 41) considered collected P. germari and Eubostrychoceras mat- sists of the following molluscan species: Crem- it a Protexanites also of late Coniacian age sumotoi Cobban 1987b approximately 25 ft noceramus deformis erectus, Didymotis variabilis as did Kennedy and Cobban (1991a, p. 53). (7.7 m) above the base of the Austin Chalk Gerhardt, and Forresteria sp. J. D. Powell col- Smith (1981, p. 21) reported the species in Val Verde County. The helicoid ammonite lected Scaphites semicostatus Roemer 1852 (Ken- (identified by Young) from 10 ft (3 m) above Eubostrychoceras was known previously from nedy et al. 2004) from the Allocrioceras ledge in the base of the Atco Formation of the Austin the D-Cross Tongue of the Mancos Shale in the Pico Etereo area in northern Chihuahua Group at Pinto Creek and Sycamore Creek Doña Ana County, New Mexico, near Davis (USGS locality D14397). The scaphite was col- southwest of Del Rio in Kinney County Well, approximately 60 mi (100 km) north of lected also by Freeman from the Austin Chalk associated with a late Turonian inoceramid El Paso, where it was associated with P. germa- 52 ft (16 m) above a bed containing the upper (Mytiloides sp. identified by E. G. Kauffman). ri and M. incertus. The “Bostrychoceras” noted Turonian Prionocyclus at USGS locality D2457 The ammonite at hand (USGS D14557) from by Powell (1967, p. 318) from a higher level in southwestern Terrell County. Roemer’s Pinto Creek seems better assigned to Pri- than Morrowites depressus in Jeff Davis County, species seems to be the same as the European onocyclus quadratus Cobban 1953b of late Texas, is probably E. matsumotoi. S. kieslingswaldensis Langenhan and Grundey Turonian age. Smith (1981, p. 21) collected 1891 that straddles the Turonian–Coniacian the middle Coniacian ammonite Peroniceras Turonian–Coniacian boundary boundary (Kaplan et al. 1987). Roemer’s spe- westphalicum 65 ft (19.8 m) above the base cies occurs also in the Allocrioceras ledge in the of the Austin at Pinto Creek and the late At the Second International Symposium on Big Bend National Park, where large collec- Coniacian inoceramids identified by E. G. Cretaceous Stage Boundaries, Brussels, Bel- Kauffman as “Inoceramus stantoni Sokolow” gium, 1995, the first occurrence of the inoc- tions (Cooper et al. 2008) reveal that the spe- cies is dimorphic. at 68 ft (20.7 m) and “Inoceramus sp. aff. eramid bivalve Cremnoceramus rotundatus I. (Magadiceramus) subquadratus Schlüter” at (of Tröger 1967, non Fiege 1930) was recom- 143–147 ft (43.6–44.8 m) above the base. Lower Coniacian mended as marking the Turonian–Coniacian An early Coniacian fauna has been boundary. Soon after that, Walaszczyk (in described recently from the “Austin Group” Walaszczyk and Cobban 2000) determined Kennedy and Cobban (1991a) recognized three interval range zones of the ammonite at the El Rosario quarry in northwestern that the species was a junior synonym of Coahuila approximately 100 km (62 mi) Inoceramus erectus Forresteria and part of a fourth in the lower Meek 1877, a species now southeast of Big Bend National Park (Stin- placed in Cremnoceramus, and so C. deformis Coniacian rocks of the central and southern nesbeck et al. 2005). Two zones were recog- erectus now marks the boundary. Walaszc- part of the Western Interior, and Walaszczyk nized: a lower one of Cremnoceramus deformis zyk and Cobban (2000) treated C. erectus and Cobban (2000) recognized four inocer- erectus and an upper one of C. crassus incon- as a chronologic subspecies of C. deformis amid interval zones in the lower Coniacian. stans. The following molluscan fossils were (Meek 1871). The inoceramid zonation for Ammonite zone Inoceramid zone listed from the lower zone: the upper Turonian–lower Coniacian of the Western Interior modified from Walaszczyk Forresteria alluaudi Cremnoceramus crassus Cremnoceramus deformis erectus (Meek) and Cobban (2000, table 1) is as follows. crassus Forresteria (F.) brancoi (Solger) Peroniceras (P.) tridorsatum (Schlüter) Substage Inoceramid zone Forresteria hobsoni Cremnoceramus crassus inconstans Scaphites (S.) frontierensis Cobban Scaphites (S.) uintensis Cobban Cremnoceramus crassus crassus Forresteria brancoi Cremnoceramus deformis Scaphites (S.) sagensis Cobban lower Cremnoceramus crassus inconstans dobrogensis Coniacian Scaphites (S.) cf. preventricosus Cobban Cremnoceramus deformis dobrogensis Forresteria peruana Cremnoceramus deformis The following molluscan fossils were listed (part) erectus Cremnoceramus deformis erectus from the upper zone: Cremnoceramus waltersdorfensis Forresteria peruana represents the upper Cremnoceramus crassus inconstans (Woods) part of its range, inasmuch as the species Peroniceras cf. P. (P.) dravidicum (Kossmat) upper Mytiloides incertus Turonian straddles the Turonian–Coniacian bound- Gandryceras mite (von Hauer) Inoceramus perplexus ary. The ranges of F. brancoi and F. hobson Scaphites cf. S. (S.) preventricosus Cobban Rocks of early Coniacian age are prob- overlap as do the ranges of Cremnoceramus In addition, Baculites yokoyamai Tokunaga ably nonmarine west of El Paso (Young 1983, dobrogensis and C. crassus inconstans. and Shimizu and Neocrioceras sp. were noted fig. 14), and the ammonite record is poor in the Young (1963, p. 18) divided the Coniacian but not assigned to a zone. marine rocks of that age in Trans-Pecos Texas of Texas and the Gulf Coast into lower and Young and Woodruff (1985) treated the southeast of El Paso. The inoceramid record, upper substages with the following three stratigraphy and paleontology of the Aus- however, is much better and more useful. zones of ammonites. tin Chalk in its type area in central Texas,

August 2008, Volume 30, Number 3 Ne w Me x i c o Ge o l o g y 81 where they termed it the “Austin Division” from near Ojinaga of the Rio Grande border Young (1969, p. 44), a heteromorph ammo- made up of seven formations. Peroniceras area, and P. tridorsatum (Schlüter), identified nite, was noted with Santonian fossils in Jeff haasi and P. westphalicum were assigned to as P. moureti de Grossouvre by Young (1963; Davis County but not assigned to a zone. the middle Coniacian and Prionocycloceras see Klinger and Kennedy 1984, p. 189). There is no international agreement about gabrielense to the upper Coniacian. Klinger Records of middle Coniacian inocer- the substages and ammonite zonation of the and Kennedy (1984, p. 169) noted the close amid bivalves seem to be missing along Santonian (Lamolda and Hancock 1996). resemblance of P. haasi to the middle Coni- the transect. This is odd because the com- Most authors recognize lower and upper acian P. subtricarinatum (d’Orbigny) and mon middle Coniacian genus Volviceramus substages. A threefold subdivision based considered it as possibly d’Orbigny’s spe- is known from many localities north of the on scaphitid ammonites in the central and cies. Böse (1928, p. 268) figured a specimen transect and usually from carbonate rocks northern parts of the Western Interior was as Peroniceras aff. subtricarinatum from near like those in southwest Texas. recommended by Scott and Cobban (1964, Ojinaga in northeast Chihuahua. Klinger table 3). As revised slightly by Cobban (1994, and Kennedy (1984, p. 157) consider it a fig. 2), it is shown in Figure 2 and below. Peroniceras (P.) subtricarinatum. The small Upper Coniacian Substage Ammonite zone specimen (USGS D14456), mentioned by Young (1963) described his new species Smith (1981, p. 21) from 143 ft (43.6 m) Prionocycloceras hazzardi and Paratexanites Desmoscaphites bassleri above the base of the Austin approximately sellardsi from his upper Coniacian Priono- upper 20 mi (37 km) southeast of Del Rio, iden- Santonian Desmoscaphites erdmanni cycloceras gabrielensis Zone. Both species are tified by Young as Protexanites? sp. indet. Clioscaphites choteauensis assigned to Protexanites (Matsumoto 1965a, and by one of us (W. A. Cobban) as ques- p. 41). Young recorded the species from middle Clioscaphites vermiformis tionable juvenile whorls of Peroniceras haasi, Santonian closely resembles in size and ornament the Brewster County, Texas. The heteromorph small specimen assigned to Peroniceras ammonite Phlycticrioceras sp. cf. douvillei (Grossouvre) was also recorded from Trans- lower Clioscaphites saxitonianus (Zuluiceras) bajuvaricum (Redtenbacher) by Santonian Kennedy and Cobban (1991a, pl. 6, fig. 8) Pecos Texas (Young 1963, p. 45), and Clark (1963) recorded P. douvillei from Brewster of middle Coniacian age and is probably We apply a threefold division for the San- County. That species is considered a junior that species. Smith (1981, p. 22), however, tonian in Trans-Pecos Texas but use Young’s synonym of Hamites trinodosus Geinitz 1850 would place this part of the Austin in the updated texanid species (Fig. 2). lower Santonian on the basis of planktonic now placed in Phlycticrioceras and known Foraminifera. from Europe, Mexico, and the United States Substage Ammonite zone Two fragments of Peroniceras cf. dravidi- (Kennedy and Cobban 1991a, p. 57). Another upper Plesiotexanites shiloensis cum Kossmat were collected by Val Freeman upper Coniacian ammonite from southwest Santonian Texanites texanus gallicus and Cobban from the uppermost beds of the Texas noted by Young (1963, pp. 120, 124) is Texasia dentatocarinata (Roemer) from Kin- Boquillas Formation in Lozier Canyon in middle Texanites texanus texanus southwestern Terrell County, Texas. These ney County and from the Study Butte area of Santonian fragments (USGS D2451) may be of early Brewster County. Wolleben (1967) described as Placenticeras colquitti, a new species that Coniacian age. Freeman and Cobban also col- lower Plesiotexanites stangeri densicostus lected a specimen (USGS D14510) of Crem- he assigned to the upper Coniacian part of Santonian noceramus crassus crassus (Petrascheck) of late the Ojinaga Formation. early Coniacian age in Lozier Canyon about Young (1963, p. 69) described a few small 100 ft (30 m) above the base of the Austin. fragments of an ammonite as the new spe- Santonian Stage Keith Young noted the following early cies Prionocycloceras adkinsae from the upper Coniacian species in an unpublished man- part of the Chispa Summit Formation Lower Santonian near Chispa Summit; and Wolleben (1967, uscript on the Coniacian–lower Campanian Texanites stangeri (Baily) densicostus ammonites of Trans-Pecos Texas: p. 1152) recorded it from the Ojinaga Forma- tion associated with Placenticeras colquitti. (Spath), the guide fossil to the oldest Forresteria alluaudi (Boule, Lemoine, and The specimens illustrated by Young and ammonite zone of the lower Santonian, Thevenin) Wolleben suggest assignment to the late was recorded by Young (1963, p. 88) from the inoceramid zone of Cladoceramus undu- Forresteria cf. peruana (Brüggen) Coniacian Protexanites. Allocrioceras hazzardi Young latoplicatus in Brewster County. A single Baculites cf. yokoyamai Tokunaga and ammonite found as float below the Clado- Shimizu Santonian zonation ceramus undulatoplicatus Zone in Brewster Yezoites aff. cobbani (Collignon) County, Texas, was described as the new Young (1963) divided the Santonian of genus and species Defordiceras hazzardi by Texas and the Gulf Coast into a lower San- Young (1963, p. 118). Wright (1996, p. 198) Middle Coniacian tonian consisting of three zones of Texan- believed it to be a pathologic specimen. As noted earlier, Young and Woodruff ites and an upper Santonian consisting of a Young (1963, p. 88) reported T. stangeri (1985) recognized Peroniceras westphalicum single Texanites Zone as follows. densicostus from near the top of the Fizzle as a zonal fossil of the middle Coniacian. Substage Ammonite zone Flat Lentil of the Terlingua Formation of Moon (1953) in Brewster County. He also The species, first described as Ammonites upper described his species Prionocycloceras adkin- westphalicus by von Strombeck (1859) from Texanites shiloensis Santonian sae from the Chispa Summit Formation Germany, is widely distributed in western Texanites texanus gallicus near Chispa Summit, and Wolleben (1967, Europe, southern Africa, Madagascar, Texas, lower p. 1152) recorded it from the Ojinaga. and sparsely in New Mexico and Wyoming. Santonian Texanites texanus texanus Freeman and Cobban found it in Lozier Texanites stangeri densicostus Middle Santonian Canyon in southeast Terrell County approxi- The Santonian zonation was followed by mately 125 ft (38 m) above the base of the Young (1982) in his great summary of the Ammonites from the middle Santonian zone Austin. Other middle Coniacian ammo- Cretaceous rocks of central Texas, but a lit- of Texanites texanus texanus are uncommon nites from southwest Texas and adjoining tle later Young and Woodruff (1985, figs. 1, and yield that species near Del Rio as well parts of Mexico include P. subtricarinatum 2) replaced T. shiloensis with Bevahites beva- as the holotype of Texanites texanites twin- (d’Orbigny), recorded by Böse (1928, p. 268) hensis Collignon. Bostrychoceras braithwaitei ingi Young from Brewster County (Young

82 Ne w Me x i c o Ge o l o g y August 2008, Volume 30, Number 3 FIGURE 1— Map showing the line of transect from Virden, New Mexico, southward to El Paso, Texas, and then down the Rio Grande area to Del Rio, Texas. August 2008, Volume 30, Number 3 Ne w Me x i c o Ge o l o g y 83 84 84 Interior of the United States, and the upper middle Turonian through Campanian zonation is based on on based is zonation Campanian through Turonian middle upper the and States, United the of (2006). Interior al. et Cobban from Westernthe of part northern modified and central the in are abundant especially are ammonites ages baculitid and Scaphitid radiometric and zones inoceramid and ammonite Interior Texas.southern areain Rio Del the to Westernkm) (800 mi 500 southeastwardmorethan Mexico New west Virdensouth- from in transect a along localities key 12 recordat molluscan Cretaceous Upper 2— FIGURE N w e M o c i x e G o l o e g y

August2008, 3 Volume Number 30,

Pen Formation to that zone, but not the index species; index the not but zone, that to letters: following the by indicated are locality each at collected fossils diagnostic Age dominant. are ammonites collignonicerid where them. These ammonites are scarce in the southern part of the Western Interior into Trans-Pecos Texas, fossil or tentative identification. Verticalidentification. hiatuses. tentative indicate or lines fossil = zonal index ammonite species; ammonite index zonal = a = zonal index inoceramid species; and species; inoceramid index zonal = i = ammonite species confined species ammonite = o

= poorly preserved poorly = ? Pen Formation 1963, pp. 81, 82). The holotype and only the Austin Group southeast of Del Rio on the zonal fossil came from Tequesquite specimen known from southwest Texas of the American side of the Rio Grande not far Creek in Kinney County, and the holotype Muniericeras? twiningi Young from Brewster from Jiménez, Mexico. of S. uddeni Young came from Brewster County may be from this zone. A collection Maxwell et al. (1967, pp. 77–78) recorded County. Another specimen assigned to S. (USGS 1467) from the San Carlos Forma- a “dwarf fauna” of small bivalves, gastro- chicoense (Trask) by Young (1963, p. 106) tion of Presidio County made by T. W. pods, and ammonites near the middle of came from the Study Butte area in Brewster Vaughan (1900, p. 79) contains Clioscaphites the approximately 213-m-thick (700-ft-thick) County. Another Texanitinae, Bevahites vermiformis (Meek and Hayden), the zonal Pen Formation near Study Butte in Brewster costatus Collignon subsp. coahuilaensis was index fossil for the middle Santonian of the County. A collection by W. S. Adkins at the described by Young (1963, p. 96) from the Western Interior (Fig. 2). Texas Memorial Museum in Austin was Jiménez area, Coahuila, and Australiella examined by W. J. Kennedy and illustrat- pattoni Young was recorded from the Davis ed by Kennedy and Cobban (1991b), who Upper Santonian Mountains area, Jeff Davis County. referred to the fossils as the Boehmoceras The holotype of Pseudoschloenbachia chis- Young (1963) recognized only a Texanites fauna. Three specimens collected by L. W. paensis Adkins (1929, p. 210) was said to be shiloensis Zone for the upper Santonian Stephenson in 1948 from the Study Butte from the San Carlos Formation of Presidio and recorded that species from southwest area were also illustrated by Kennedy and County, but Wolleben (1967) reported it from Texas in Kinney and Presidio Counties and Cobban (1991b, locality 26335). The ammo- the older Ojinaga Formation, and C. L. Metz Coahuila, Mexico. Young noted Texasia den- nites from the Study Butte area, as now (pers. comm. 1992) collected several speci- tatocarinata (Römer) from Kinney County known, consist of the following species: mens from the uppermost concretion unit and from the Study Butte area in Brewster Pseudoschloenbachia mexicana (Renz) in the Ojinaga in the Gettysburg Peak quad- County. Bevahites bevahensis Collignon and Reginaites subtilis Kennedy and Cobban rangle in Presidio County. the holotype of Reginaites durhami were also Glyptoxoceras spp. Eupachydiscus sp. was recorded by Young found in Kinney County. The holotype of Scaphites leei Reeside, form I (1963, pp. 60–61) from Tequesquite Creek in Pseudoschloenbachia wilsoni Young came from Baculites capensis Woods Kinney County, and from northern Coahuila. Presidio County. Regarding the latter spe- Boehmoceras arculus (Morton) Robust species of Placenticeras, often assigned cies, a collection (USGS 1467) from the San The age is late Santonian, Texanites shiloensis to Stantonoceras Johnson 1903, are abundant Carlos Formation of Presidio County made Zone of Young. Scaphites leei form I occurs in the upper part of the Ojinaga Formation by T. W. Vaughan (1900, p. 79) contains in the late Santonian Desmoscaphites erd- in Presidio County. Wolleben (1967) placed P. wilsoni and Clioscaphites vermiformis (Meek manni Zone of the Western Interior region them all in P. syrtale (Morton) with the sub- and Hayden). Lot 1467 includes a lengthy (Cobban 1969, p. 14). Young (1969, table 2) species syrtale, adkinsi, and rooneyi. Young list of molluscan species and may represent later considered T. shiloensis and B. bevahen- (1963) had earlier recognized the placentic- several stratigraphic levels inasmuch as P. sis as early Campanian in age. eratids from the San Carlos area as Stantono- wilsoni is upper Santonian according to Texanites stangeri densicostus was assigned ceras guadalupae (Roemer), S. sancarlosense (Hyatt), and S. pseudosyrtale (Hyatt). Other Young, and C. vermiformis is a zonal index to the subgenus Plesiotexanites by Matsumoto ammonites from the Submortoniceras teques- fossil for the middle Santonian of the middle (1970, p. 285) and to the full genus Plesiotex- anites by Klinger and Kennedy (1980, p. 67). quitense Zone from southwest Texas reported and northern part of the Western Interior. Texanites texanus texanus and T. texanus galli- by Wolleben include Texanites lonsdalei Young Pseudoschloenbachia mexicana was cus as well as T. texanus twiningi Young were and Glyptoxoceras ellisoni Young. described by Renz (1936) as Schloenbachia grouped by Klinger and Kennedy (1980, The late J. P. Conlin (1908–1972) pur- bertrandi de Grossouvre var. mexicana from p. 162) as T. texanus s.l. Texanites shiloensis chased a collection of ammonites from near Jiménez in northern Coahuila. Young was assigned to the subgenus Plesiotexanites Presidio County labeled “San Carlos shale (1963, p. 121) raised the variety to a spe- by Klinger and Kennedy (1980, p. 65). facies.” In the collection was a specimen cies of Pseudoschloenbachia, designated one The only ammonite from southwest of Neogauthiericeras zafimahovai Collignon, of Renz’s specimens as the holotype (lecto- Texas from the lower upper Santonian a species noted by Kennedy and Cobban type), and considered it as a late Santonian Texanites texanus gallicus Zone recorded by (1990c) and assigned to the S. tequesquitense species. Among the fossils of the USGS at the Young (1963, p. 82) is Texanites texanus twin- Zone. The Conlin collection includes sever- Denver Federal Center is a small collection ingi from Brewster County, a species that S. tequesquitense of ammonites (USGS 14678) that includes al good specimens of from begins in the upper part of the underlying P. mexicana from 8 mi (13 km) south of Oji- the Porvenir area of Presidio County. T. texanus texanus Zone. naga, Chihuahua. The species is present also Young (1963, p. 28) recorded 21 species of in the J. P. Conlin collection from near Study ammonites from the lower Campanian zone Butte in Brewster County (USGS D14555). Campanian Stage of Menabites (Delawarella) delawarensis in the Renz (1936, p. 3) described also the new spe- Gulf Coast area of which 11 occur in south- cies Pachydiscus (Parapachydiscus) jimenezi as Lower Campanian west Texas including the zonal fossil. Ken- nedy et al. (1997, p. 3) noted that D. delawa- a Santonian form from the Jiménez area, but In his 1963 treatment of the Austin Chalk, rensis has a very long vertical range into the Young (1963, p. 59) assigned it to Eupachy- Young divided the Campanian into lower Delawarella sabinalensis Zone of Young, and discus and to the lower Campanian. Another and upper parts. Three ammonite zones recommended that the two zones could be new species, described by Renz (1936, p. 57) were defined for the lower Campanian and combined into a single zone of Baculites taylo- as Mortoniceras densinodosum from the Jimé- one for the upper Campanian. The three rensis Adkins. Delawarella is now considered nez area and assigned to the Santonian, was zones of the lower Campanian are shown Menabites later considered a Menabites by Young (1963, below. a subgenus of Collignon (1948; see p. 108), who placed it in the lower Campa- Wright 1996, p. 197). Menabites (Delawarella) nian Submortoniceras tequesquitense Zone. Substage Ammonite zone delawarensis (Morton) occurs in the Pen For- The slender, densely ribbed whorls of an Delawarella sabinalensis mation in Big Bend National Park (Maxwell lower et al. 1967, pp. 75, 78) and in the San Carlos ammonite identified as Puzosia (Parapuzosia) Campanian Delawarella delawarensis corberica de Grossouvre by Renz (1936, p. 5) Formation in Presidio County (Young 1963, Submortoniceras tequesquitense from the Jiménez area and assigned to the p. 112). Young recorded Submortoniceras Santonian was found by Young (1963, p. 52) Young (1963, p. 29) listed 23 species of vanuxemi (Morton) from the M. delawarensis to be the inner whorls of the huge ammo- ammonites from the zone of Submortonic- Zone of Brewster County. This species is now nite Parapuzosia bosei Scott and Moore 1928 of eras tequesquitense of which 10 were known placed in Menabites (Cobban and Kennedy early Campanian age. The holotype is from from southwest Texas. The holotype of 1991, p. 2). The holotype of Submortoniceras

August 2008, Volume 30, Number 3 Ne w Me x i c o Ge o l o g y 85 sancarlosense Young 1963 is from the upper Europe occurs in the basal upper Campanian shale member, (3) a limestone and calcare- part of the San Carlos Formation of Presidio zone of H. vari (Schlüter), which is overlain by ous shale member containing fossiliferous County, and the holotype of S. maricalense the upper Campanian zone of Trachyscaphites concretions, and (4) an upper shaly unit that Young is from Brewster County in Big Bend spiniger (Schlüter) (for example, Kaplan et al. grades upward into sandstone. These units National Park. Submortoniceras candelariae, 2005). Young (1963) illustrated several frag- have been termed the flag member, lower another species described by Young from the ments of H. marroti from the Anacacho Lime- shale member, Bridge Creek Limestone M. delawarensis Zone, came from Brewster stone from south-central Texas, but none Member, and upper sandstone and shale County. It is also present in the J. P. Conlin from southwest Texas. Kennedy and Cob- member (Cobban et al. 1989, fig. 3). collections from the Porvenir area of Presi- ban (2001) recorded a single fragment from Graphic sections for the sequence of the dio County. The species is better assigned to the Anacacho of Medina County, Texas, and Virden area are shown by Cobban et al. Texanites (Plesiotexanites) according to Mat- described the new species H. minor from the (1989, fig. 15), Lucas and Estep (1998, fig. Wolfe City Sand that underlies the Pecan Gap sumoto (1970, p. 279) and Klinger and Ken- 16), and Lucas et al. (2000, fig. 3). There, Chalk (Anacacho equivalent) of northeastern nedy (1980, p. 65). the flag member yielded Metoicoceras mos- Texas (Cobban and Kennedy 1993), where Two huge ammonites, Parapuzosia bosei byense it is associated with Trachyscaphites spiniger. from limestone concretions, 10–15 ft and P. americana, were described by Scott Assuming that one or more of these species (3–5 m) above the base, and the lower shale and Moore (1928) from the Austin Group of Hoplitoplacenticeras will be found in Trans- member had M. frontierense, Eucalycoceras southeast of Del Rio. They were assigned Pecos Texas, Young’s zone is herein treated as pentagonum, Moremanoceras scotti, Euompha- to the Santonian, but Young (1963, p. 52) Hoplitoplacenticeras spp. (Fig. 2). loceras merewetheri, and the heteromorph placed them in the M. delawarensis Zone. Adkins (1933, p. 475) recorded the pres- ammonites Hamites cf. simplex, H. salebro- He also figured a specimen of P. sp. aff. ence of an ammonite resembling Libycoceras sus, Metaptychoceras hidalgoense, Neostlingo- P. bradyi Miller and Youngquist (1946) from Hyatt southeast of Terlingua, Texas. The ceras procerum, and N. virdenense (Cobban the lower Campanian of Jeff Davis County. specimen is probably Manambolites ricensis et al. 1989, p. 16). The last species has been Renz (1936) described the new species Young (1963, p. 127), an early Campanian recorded from the upper Cenomanian Caly- Pachydiscus (Parapachydiscus) jimenezi from species inasmuch as Adkins (p. 508) noted coceras guerangeri Zone of England (Wright the Jiménez area of northern Coahuila the occurrence of “Libycoceras(?) n. sp.” along and Kennedy 1996, p. 330). Metoicoceras ges- and assigned it to the Santonian. Young with “Mortoniceras cfr. delawarense” and other linianum occurs in the Bridge Creek Member (1963, p. 59) placed it in Eupachydiscus and ammonites in the Aguja Formation. in the Virden area. Euomphaloceras costatum assigned it to the M. delawarensis Zone. He and Pseudaspidoceras pseudonodosoides occur also described Eupachydiscus sp. from Kin- high in the Bridge Creek Member. Ammo- ney County and Coahuila. Localities nites were not found in the upper sandstone After completing a thesis on the San and shale member, but the presence there of Carlos beds of Presidio County, C. L. Metz Formations and stratigraphic positions of Mytiloides puebloensis indicates an early Turo- (Blinn College, Bryan, Texas) donated some diagnostic fossils are shown in Figure 2. At nian age (Walaszczyk and Cobban 2000). ammonites to the USGS. Among them were the west end of the transect near Virden, New Mexico, strata of late Cenomanian age several specimens of Baculites vaalsensis Ken- Big Burro Mountains nedy and Jagt 1995, a species described from rest unconformably on Precambrian rocks, Belgium from the Vaals Formation that con- and eastward from Virden to the Cookes The lithology and fossil sequence in the Big tains Scaphites hippocrepis III of early, but not Range, the middle Cenomanian and Burro Mountains is treated by Cobban et al. earliest, Campanian age. Kennedy and Jagt younger ammonite and inoceramid records (1989, pp. 15, 16). The flag unit of the Man- also noted the occurrence of the baculitid in are missing because the rocks are nonma- cos has a basal conglomerate of chert and New Jersey and in the Western Interior. rine. This middle Cenomanian hiatus may quartzite pebbles that rests disconformably J. P. Conlin obtained a specimen from the extend through Trans-Pecos Texas to or on the Beartooth Quartzite. Ammonites col- “San Carlos shale facies” of the Porvenir area beyond the Del Rio area. A minor hiatus lected from calcareous concretions 11–16 ft in western Presidio County that appears to may exist at the top of the upper Cenoma- (3–5 m) above the base consist of Moremano- be Ishikericeras Matsumoto (1965b, p. 236). nian, where records of the Nigericeras scotti ceras sp., Tarrantoceras sp., and Hamites sp., The specimen is missing from the Conlin col- Zone are lacking. which suggest the upper Cenomanian zone lection, but there is a good plaster cast of it Strata above the Mancos Shale in south- of Calycoceras canitaurinum as does the Inoc- (Conlin 14932). Conlin assigned the specimen western New Mexico are nonmarine and not eramus prefragilis stephensoni? collected from to the “Submortoniceras candelariae Zone.” treated in this report. In the area from Sierra near the base of the flags (D11014). The lower The zonal species of Delawarella sabinalen- de Cristo Rey to Chispa Summit, records of shale unit is thin and concealed, but above it sis was described by Young (1963, p. 112), marine fossils above the Boquillas, Ojinaga, is a 15-ft-thick (4.6-m-thick) sandy, calcareous who mentioned the occurrence of a speci- and Chispa Summit Formations are lack- coral thicket (Archohelia dartoni Wells) that men from “the Terlingua formation on Tor- ing. Farther southeastward from the Chispa contains Metoicoceras geslinianum and other nillo Creek, Big Bend National Park, Trans- Summit area to the Del Rio area, marine fos- fossils of the upper Cenomanian Euompha- Pecos Texas.” Delawarella sabinalensis is the sils as young as late Campanian are known. loceras septemseriatum Zone. Four feet above only ammonite recorded by Young from this the coral thicket is a 5-ft-thick (1.5-m-thick) zone in southwest Texas. This species is now Virden shale unit that contains limestone concre- assigned to the genus Menabites, subgenus tions with Burroceras clydense overlain by Delawarella. The shaly marine Cenomanian–Turonian limestone concretions with Neocardioceras strata of southwestern New Mexico have juddii and Pseudaspidoceras pseudonodosoides. long been termed the Colorado Formation. The highest of the last concretions represent Upper Campanian Molenaar (1983, p. 213 and fig. 4) pointed a hardground with corroded ammonites that Adkins (1933, p. 474) noted the European out that these strata represent a tongue of the mark the end of Cenomanian deposition. upper Campanian zone of Hoplitoplacenticeras Mancos Shale, and that Mancos Shale should Resting sharply on the hiatus concretions vari (Schlüter) in the basal Aguja Formation in be applied (see also Lucas and Estep 1998, is silty shale containing an occasional Quit- the Big Bend area. The zone overlies a zone of pp. 51–53). In the area from Virden eastward maniceras reaseri Powell of the lower Turo- “Mortoniceras aff. delawarense.” Young (1963, to the Cookes Range, much of the Mancos nian zone of Pseudaspidoceras flexuosum. The p. 28) recognized for the Gulf Coast area a Shale consists of the following lithologic presence of Mytiloides puebloensis still higher basal late Campanian zone of Hoplitoplacen- units: (1) a basal ledge-forming flaggy mem- in the section suggests the lower Turonian ticeras marroti (Coquand 1859). This species in ber of siltstone, sandstone, and shale, (2) a zone of Vascoceras birchbyi.

86 Ne w Me x i c o Ge o l o g y August 2008, Volume 30, Number 3 Cookes Range Bits of a large ammonite that has alternate et al. 1989, fig. 1). Graphic sections of the primary and secondary ribs (USGS D14390) Chispa Summit Formation were presented At one locality in the Cookes Range (Cobban were collected approximately 100 ft (30 m) by those authors. 1987a, fig. 1, locality D10104), several speci- above the base, and could be from Calyco- At its type locality, the Chispa Summit mens of the early Cenomanian ammonite ceras canitaurinum. Associated fragments of Formation rests disconformably on the Buda Mantelliceras (probably M. budaense Adkins) Inoceramus resemble I. prefragilis stephensoni Limestone and contains the early Cenoma- were found in sandy, nodular limestone of early late Cenomanian age. nian Acompsoceras inconstans and Forbesiceras at the top of the Sarten Sandstone, which brundrettei faunas in the basal beds. A col- suggest an age equivalent to the upper lection 15 ft (4.6 m) above the base contains part of the Buda Limestone of Trans-Pecos Cieneguilla area Acanthoceras bellense and other fossils of that Texas. The collection, which is considerable, Upper Cretaceous strata and fossil content in middle Cenomanian zone. Calycoceras canitau- includes a specimen identified as Turrilites the Cieneguilla area, which borders the Rio aff. T. costatus Lamarck (Cobban 1987a, p. 3) rinum is present 59 ft (18 m) above the base. Grande in Chihuahua, Mexico, and Hud- that is now assigned definitely to T. costatus The next 60 ft (18.5 m) of calcareous shale did speth County, Texas were treated by Powell (Hook and Cobban 2007). not yield fossils. Limestone beds in a calcare- (1961, 1963a, b, 1965), Reaser (1970, 1974), Much of the Mancos Shale in the Cookes ous shale unit 120–125 ft (36.5–38.5 m) above Jones and Reaser (1970), Kennedy and Cob- Range area is very fossiliferous. The flag the base contain Metoicoceras geslinianum, ban (1988), Kennedy et al. (1989), and Cob- member has a large fauna of the lowermost Euomphaloceras septemseriatum, Sciponoceras ban and Kennedy (1989). The stratigraphic upper Cenomanian zone of Calycoceras can- gracile, and other ammonites of the upper sequence consists of the Eagle Mountains itaurinum with the ammonite genera Boris- Cenomanian E. septemseriatum Zone. Pseudo- Formation and Buda Limestone of early siakoceras, Moremanoceras, Cunningtoniceras, calycoceras angolaense was recorded from Cenomanian age and the Del Rio Clay Calycoceras, Tarrantoceras, Metoicoceras, Chispa Summit 128 ft (39 m) above the base equivalent, which contains the Graysonites Hamites, Turrilites, and Neostlingoceras. The (Cobban 1988b, p. 14). Approximately a meter fauna including abundant foraminifera (Cri- E. septemseriatum lower shale member and the basal part bratina texana). The Buda Limestone, three- above the Zone is a soft bed of the Bridge Creek Limestone Member fold and nearly 850 ft (259 m) thick, contains of limestone that contains Neocardioceras jud- Vascoceras diartianum Metoicoceras contain , the Neophlycticeras (Budaiceras) fauna. dii and other ammonites whose top surfaces mosbyense Moremanoceras , and the genera , The Ojinaga Formation is at least 2,000 ft are corroded indicating a hiatus just as in Placenticeras, Forbesiceras, Cunningtoniceras, thick (610 m) and consists of a lower flaggy ammonites at the top of the N. juddii Zone in Calycoceras, Eucalycoceras, Euomphaloceras, unit 75 ft (23 m) thick, a much thicker mid- southwest New Mexico. Above the N. juddii Nannometoicoceras, Hamites, Metaptychocer- dle shale unit 1,380 ft (420 m), and an upper Zone is 26 ft (8 m) of calcareous shale lack- as, and Neostlingoceras. Calycoceras (Proeuca- sandy unit 1,010 ft (308 m) (Kennedy et al. ing molluscan fossils that probably contains lycoceras) guerangeri, guide to the European 1987, fig. 1). A fauna characterized by the the Cenomanian–Turonian boundary. A bed basal upper Cenomanian C. guerangeri early Cenomanian Acompsoceras inconstans of concretionary limestone above this bar- Zone, was found in the upper part of the Zone is present in the flaggy unit 30 ft (9 m) ren unit contains Pseudaspidoceras flexuosum, lower shale member. above the base. (See early part of the present Mammites powelli, Vascoceras proprium, and The upper part of the Bridge Creek Mem- report for an updated list of fossils.) Fossils Neoptychites cf. cephalotus. Limestone beds ber contains Euomphaloceras septemseriatum, have not been recorded from the lower one- and concretions a little above the flexuosum Metoicoceras geslinianum, Sciponoceras gracile, half of the thick middle shale unit. Powell and the genera Moremanoceras, Placenticeras, bed contain Mammites nodosoides, Morrowites (1963a) described an early Turonian fauna depressus, and other ammonites of the upper- Calycoceras, Pseudocalycoceras, Sumitomoceras, that contained Pseudaspidoceras flexuosum Vascoceras, Allocrioceras, Neostlingoceras, and most lower Turonian Mammites nodosoides from a limestone bed 990 ft (302 m) above Zone. (See Hancock et al. 1994, pp. 469–470.) Worthoceras. Calcareous hiatus concretions the base of the Ojinaga. This fauna was at the top of the Bridge Creek Member con- In the Needle Peak area approximately revised by Chancellor (1982) and Kennedy 2 km southwest of Chispa Summit, a flaggy tain Neocardioceras juddii, Pseudaspidoceras et al. (1987), and updated names are given in pseudonodosoides, and Anisoceras coloradoense sandstone unit lies at an undetermined dis- the early part of the present report. A total of tance above the M. nodosoides Zone. The mid- of the upper Cenomanian N. juddii Zone. 12 genera of ammonites is now known from The lower part of the upper shale member dle Turonian ammonite Collignoniceras wooll- the P. flexuosum Zone of Trans-Pecos Texas. gari woollgari was found 105 ft (32 m) below has yielded Pseudaspidoceras flexuosum, Fage- The lower part of the upper sandy unit is the flaggy sandstone, and C. woollgari regulare sia catinus, and Watinoceras sp. of early Turo- of early middle Turonian age. Concretions was found 39 ft (12 m) below. Limestone con- nian age. The lower part of the sandstone at the base of the unit contain Collignonic- cretions 65–98 ft (20–30 m) above the flaggy and shale member contains F. catinus, Vas- eras woollgari (Mantell), identified by Powell coceras birchbyi, and Neoptychites cephalotus. (1963b) as Selwynoceras mexicanum (Böse) sandstone contain Prionocyclus hyatti, abun- Mammites nodosoides, of latest early Turonian from Powell’s Cannonball Hill locality. For dant Coilopoceras springeri, and other ammo- age, was found higher in the member. other ammonites from that locality, see the nites of the middle Turonian P. hyatti Zone. A early part of the present report. The middle barren shaly unit, possibly 150 ft (45 m) thick Sierra de Cristo Rey Turonian Prionocyclus hyatti Zone was not separates the hyatti beds from calcarenite and observed in the Cieneguilla area, but Powell calcarenitic concretions with Scaphites warreni Strain (1968) applied the name Boquillas (1965, p. 519) noted the occurrence of P. hyatti and Prionocyclus wyomingensis of late mid- Formation to marine Upper Cretaceous beds in the Cuchillo Parado area approximately dle Turonian age. A thin bed of sandstone resting on the Buda Limestone at Sierra de 100 mi (160 km) south of Cieneguilla, and slightly higher has Inoceramus perplexus of Cristo Rey (Cerro de Cristo Rey, Cerro de Kennedy and Cobban (1988) figured speci- earliest late Turonian age, and a concretion- Muleros) west of El Paso, Texas, but later mens from that area. ary limestone still higher yielded the middle (1976) he suggested that the names Ojina- late Turonian Mytiloides incertus. At another ga or Chispa Summit could be just as well locality in the Chispa Summit area, the early applied. We are following Lovejoy (1976), Chispa Summit area Coniacian Cremnoceramus deformis erectus and who mapped the beds as Boquillas at Sierra The thick shale of the Ojinaga Formation Forresteria sp. were collected. The J. P. Conlin de Cristo Rey. We examined only the lower was deposited in the Chihuahua trough collection (see pp. 85 and 86) from the San part of the Boquillas, which has a fossilifer- along the Chihuahua–Texas border area, Carlos shale facies near Porvenir, Presidio ous calcarenitic limestone at the base. The whereas the equivalent Chispa Summit For- County, 15 mi (27 km) southwest of Chispa molluscan fauna that represents the middle mation was deposited to the northeast as a Summit, contains several good specimens Cenomanian Acanthoceras amphibolum Zone shelf facies on the Diablo platform (Powell of the lower Campanian zonal index spe- is listed in the first part of the present report. 1965, fig. 2; Lehman 1986, fig. 7; Kennedy cies, Submortoniceras tequesquitense, as well as

August 2008, Volume 30, Number 3 Ne w Me x i c o Ge o l o g y 87 ammonites restricted to the overlying Mena- woollgari regulare Zone], Prionocyclus hyatti A white limestone near the middle of the bites (Delawarella) delawarensis Zone. approximately 2,130 ft (650 m), and Coilopo- Ernst Member has yielded the middle Turo- ceras higher. nian fossils Collignoniceras woollgari (Man- San Carlos tell)? as float, Prionocyclus hyatti, and Inocera- Big Bend National Park mus howelli White, both in situ. High in the Vaughan (1900, p. 81) gave the name San Car- Ernst Member, the Coopers have collected los Formation to the fossiliferous sandstone The authors have not carried out field work the upper Turonian inoceramids Inoceramus and shale with some coal exposed at the for- in the Big Bend National Park, and the fol- perplexus Whitfield, I. dakotensis Walaszczyk mer San Carlos store and San Carlos Coal lowing account is based mainly on collec- and Cobban, Mytiloides incertus (Jimbo), Company’s coal mine in northwestern Presi- tions made by Maxwell et al. (1967), Cooper M. scupini (Heinz), and Cremnoceramus wal- dio County, Texas. He included shaly rocks et al. (2008), and Keith Young (University of tersdorfensis (Andert). The Allocrioceras haz- now assigned to the Ojinaga Formation. A Texas, Austin). zardi beds at the top of the Ernst contain generalized graphic section by Wolleben (1967, Maxwell et al. (1967) and Maxwell and the important lower Coniacian inoceramid fig. 2E-F) shows the restricted San Carlos For- Dietrich (1972) recognized the following Cremnoceramus deformis erectus (Meek). mation to consist of lower and upper sand- Upper Cretaceous sequence of strata in Maxwell et al. (1967, pp. 53, 64) reported stone members separated by a shaly member the Big Bend National Park: Aguja Forma- the ammonites Sciponoceras cf. gracilis and and to lie in the lower Campanian zone of tion, Pen Formation, Boquillas Formation Scaphites from the Allocrioceras hazzardi beds. Menabites (Delawarella) delawarensis as well as (San Vicente Member, Ernst Member), Buda Collections made by the Coopers show that in the upper part of the underlying Submor- Limestone, and Del Rio Clay. the specimens of Sciponoceras are poorly pre- toniceras tequesquitense Zone. Fossils reported Those authors noted the presence of Stolicz- served Baculites (possibly B. yokoyamai Toku- by Wolleben (1967, fig. 3) from the San Carlos kaia sp. in the Del Rio and Budaiceras spp. in the naga and Shimizu) and that the scaphite is included Placenticeras syrtale rooneyi, Submor- Buda. They noted also the presence of “small Scaphites semicostatus Roemer (1852, p. 35; toniceras vanuxemi, Menabites belli, Delawarella desmoceratid ammonites”(Moremanoceras) Kennedy et al. 2004, p. 442). delawarensis, Pseudoschloenbachia cf. mexicana, near the base of the Boquillas. They rec- James and Margaret Stevens, Terlingua, and the oyster Exogyra ponderosa upatoiensis. ognized a widely distributed, prominent, Texas, are investigating the San Vicente C. L. Metz, who did a Ph.D. dissertation on ledge-forming unit of limestone and shale Member of the Boquillas Formation and the the San Carlos area (pers. comm. 1995), noted known as the “Allocrioceras beds” or “Crio- overlying Pen Formation. Many collections that carbonate concretions were abundant in ceras ledge” for the many A. hazzardi Young of fossils made by them and identified by the lower part of the middle shale member of (1963, p. 44). Maxwell et al. (1967) placed this Keith Young reveal almost all of the Coni- the San Carlos and that they contain Baculites unit in the upper part of their Boquillas For- acian–lower Campanian ammonite zones vaalsensis Kennedy and Jagt 1995. Wolleben mation. Cooper et al. (2008) have found for recognized by Young (1963). Among the key (1967, figs. 2, 3) reported the following fossils mapping purposes that the Allocrioceras bed lower Coniacian to lower Santonian fossils from concretions in the upper part of the Oji- is better considered as the top of the Ernst shown by Cooper et al. (2008, table 2) from the naga Formation: Glyptoxoceras ellisoni, Placen- Member. San Vicente Member are (in ascending strati- ticeras syrtale adkinsi, Texanites aff. omeraensis, The following discussion of fossils from graphic order): Cremnoceramus deformis erec- Submortoniceras candelariae, Pseudoschloenbachia the Ernst Member of the Boquillas Forma- tus (Meek), C. crassus crassus (Petrascheck), chispaensis, and Exogyra ponderosa upatoiensis. tion is based on Cooper et al. (2008, pp. 24–33, Protexanites bourgeoisianus (d’Orbigny), and His Placenticeras colquitti is said to come from fig. 35). Careful collecting in the lower Cladoceramus undulatoplicatus (Roemer). Young’s upper Coniacian Prionocycloceras 16 inches (40 cm) of the Ernst Member in Big J. D. Powell collected and donated to gabrielensis Zone. Vaughan (1900, p. 75) listed Bend National Park has revealed the presence the U.S. Geological Survey a phragmocone many bivalves, gastropods, and cephalopods of Moremanoceras bravoense Cobban and Ken- of the scaphitid Trachyscaphites spiniger collected by him and T. W. Stanton in 1895 nedy and Euhystrichoceras adkinsi (Powell) of (Schlüter) that came from just outside Big from “1 mi south of store, San Carlos.” The the early Cenomanian Acompsoceras inconstans Bend National Park. The specimen (USGS collection (USGS 1467), however, is a mixture Zone. Inoceramus arvanus Stephenson collect- D14461), associated with a worn Pachydis- of San Carlos and Ojinaga species because it ed from approximately 10 ft (3 m) above the cus aff. P. paulsoni Young, came from the includes a specimen of the early Campanian Buda may represent the middle Cenomanian “Aguja Formation” near the Study Butte Menabites (Delawarella) delawarensis and a Acanthoceras bellense Zone. The large coiled road entrance to Big Bend National Park. specimen of the middle Santonian Clioscaphi- ammonite 12 ft (3.6 m) above the contact with In terms of the Western Interior sequence of tes vermiformis. the Buda tentatively identified as Calycoceras ammonites, T. spiniger lies in the upper part sp. (Cooper et al. 2008, p. 26) is quite likely a of the Baculites obtusus–B. asperiformis Zones large A. bellense Adkins. Ojinaga–El Sobaco of Campanian age (Hoplitoplacenticeras spp. Approximately 7 ft (2 m) above I. arvanus, Zone of present report). Wolleben (1967, fig. 2; 1968, fig. 2) mea- a collection of Ostrea beloiti Logan, Tarranto- Lehman (1985, fig. 2; 1986, fig. 1) showed sured a section of Ojinaga Formation ceras sellardsi (Adkins), and Turrilites acutus the relationship of the Ojinaga, Boquillas, 4,577 ft (1,395 m) thick overlain conform- Passy indicates the middle Cenomanian San Carlos, Pen, and Aguja Formations in ably by 424 ft (129 m) of San Carlos For- Acanthoceras amphibolum Zone. This assem- the Big Bend area. He also showed that mation in the Ojinaga area. He placed the blage is followed by Inoceramus ginteren- the Pen Formation interfingered with the latter in the early Campanian Delawarella sis Pergament probably from the upper overlying Aguja Formation and that both delawarensis Zone, and noted the presence Cenomanian Metoicoceras mosbyense Zone; units rise in age eastward. In a more recent of the lower Santonian Texanites stangeri a little higher Inoceramus pictus Sowerby paper, Lehman and Tomlinson (2004, fig. 1) densicostus 1,800 ft (548 m) above the base and Pseudocalycoceras angolaense indicate the show details of the interfingering and that a of the Ojinaga. upper Cenomanian Euomphaloceras septem- westward-thinning marine unit, informally Powell (1965, p. 519, fig. 6) applied the seriatum Zone; and higher still, the inocer- called the McKinney Springs tongue of the name Chispa Summit Formation in the amids Mytiloides puebloensis Walaszczyk and Pen Formation, is present near the middle Cuchilla Parado area and recorded the fol- Cobban and M. goppelnensis (Badillet and of the Aguja. The McKinney Springs tongue lowing ammonites above the base of the Sornay) are probably from the lower Turo- rests on a marine sandstone referred to Ojinaga: Pseudouhligella elgini [Moremanoceras nian Pseudaspidoceras flexuosum Zone. These informally by Lehman and Tomlinson as the bravoense] at 10–35 ft (3–10.6 m), mantellic- middle Cenomanian–lower Turonian zones Rattlesnake Mountain sandstone member of eratines at 300 ft (91 m), a Spathites chispaen- have not been recorded previously in Big the Aguja Formation. Fossils collected from sis fauna at 1,600 ft (488 m) [Collignoniceras Bend National Park. this sandstone include Pachydiscus paulsoni

88 Ne w Me x i c o Ge o l o g y August 2008, Volume 30, Number 3 (Young), Baculites maclearni Landes, and lugubris, and Prionocyclus sp. 6 ft (1.8 m) References Hoplitoplacenticeras cf. plasticum (Paulcke). below the top (USGS D2443). The small oys- ter N. lugubris (Conrad), widely distributed Adkins, W. S., 1928, Handbook of Texas Cretaceous in the Juana Lopez Member of the Mancos fossils: Texas University, Bulletin 2838, 385 pp. Pico Etereo Adkins, W. S., 1929, Some Upper Cretaceous Taylor Shale in New Mexico, Utah, and Colorado, ammonites from Texas: University of Texas, Bul- Fossils from the Pico Etereo fluorite dis- has been recorded as far south as Coahuila letin 2901, pp. 203–211. trict in northern Coahuila, just east of (Böse 1913, pl. 8). Adkins, W. S., 1931, Some Upper Cretaceous ammo- the Big Bend area, were listed by Daugh- Freeman measured the lower 113 ft (34 m) nites in western Texas: Texas University, Bulletin erty and Powell (1963) and Powell (1965). of his Austin Chalk, which rests conformably 3101, pp. 35–72. Euhystrichoceras adkinsi and Moremanoceras on the Boquillas (Freeman 1961, fig. 1). The Adkins, W. S., 1933, The geology of Texas, Part 2, The Mesozoic systems in Texas: Texas University Bul- elgini at the base of the Boquillas indicate late Turonian inoceramid Mytiloides incertus letin 3232, pp. 239–518, pls. 2–5 (1932 imprint). the lower Cenomanian zone of Forbesiceras was collected in the lower 15 ft (5 m) of the Bailey, T. L., Evans, F. G., and Adkins, W. S., 1945, brundrettei. The presence of an undescribed Austin, and the early Coniacian Cremnoc- Review of stratigraphy of part of Cretaceous in species of the ammonite Tragodesmoceroides eramus sp. was found approximately 75 ft Tyler basin, northeast Texas: American Associa- 75 ft (23 m) above the base of the Boquil- (23 m) above the base. A specimen of Peronic- tion of Petroleum Geologists, Bulletin, v. 29, no. 2, las suggests the basal upper Cenomanian pp. 170–185. eras was found as float approximately 25 ft Barrois, C., and de Guerne, J., 1878, Description de zone of Calycoceras canitaurinum. The basal (7.6 m) higher. quelques espèces nouvelles de la Craie de l’est Coniacian Allocrioceras hazzardi ledge was Hazzard (1959) showed a zone of Coilopo- du Bassin de Paris: Société Géologique du Nord recorded 282 ft (86 m) above the base of the ceras and Glebosoceras in his upper unit (Free- Annales, v. 5, p. 42–64. Boquillas. Limestone of Austin age overly- man’s laminated unit). Glebosoceras is none Bell, G. L., Jr., 1994, Middle Turonian mosasauroids ing the Boquillas yielded the middle Conia- from the Cretaceous Boquillas Formation in the other than an inflated form of Coilopoceras. Big Bend National Park, Texas (abs.): Geologi- cian Gauthiericeras sp. 40 ft (12 m) above the Pessagno (1969) investigated the stra- cal Society of America, Abstracts with Programs, base, Cladoceramus undulatoplicatus and Tex- tigraphy and foraminiferal content of the Rocky Mountain Section, p. 3. anites texanus at the lower-middle Santonian Upper Cretaceous strata in Lozier Canyon, Birkelund, T., Hancock, J. M., Hart, M. B., Rawson, boundary 101 ft (31 m) above the base, and where he divided the Boquillas Formation P. F., Remane, J., Robaszynski, F., Schmid, F., and the lower Campanian Bevahites bevahensis Surlyk, F., 1984, Cretaceous stage boundaries— into a lower Rock Pens Member of calcare- proposals: Geological Society of Denmark, Bulle- near the top. ous siltstone, mudstone, and flaggy lime- tin, v. 33, pt. 1-2, pp. 3–20. stone and an upper Langtry Member of Böse, E., 1913, Algunas faunas del Cretacio Supe- Lozier Canyon marlstone, marl, and chalky limestone. In rior de Coahuila: Instituto Geológico de México, the Rio Grande area of Terrell, Val Verde, Boletín 30, 56 pp. Lozier Canyon, a tributary of the Rio Grande, Böse, E., 1920, On a new ammonite fauna of the and Kinney Counties, Pessagno applied the lower Turonian of Mexico: Texas University, Bul- is located in southeast Terrell County, Texas name Austin Chalk, in which he recognized letin 1856, pp. 173–252 (1918 imprint). (Sharps 1963). There, the Boquillas and lower the Atco, Dessau, Burditt, and Big House Böse, E., 1928, Cretaceous ammonites from Texas part of the Austin are well exposed and Members from other areas in Texas. and northern Mexico: Texas University, Bulletin quite fossiliferous. Hazzard (1959) referred 2748, pp. 143–312 (1927 imprint). to them as the Eagle Ford and Austin For- Chancellor, G. R. C., 1982, Cenomanian–Turonian Del Rio area ammonites from Coahuila, Mexico: Geological mations and presented two graphic sections Institutions of University of Uppsala Bulletin, n. with a few invertebrate fossils identified by The Boquillas Formation and Austin Group ser., v. 9, pp. 77–129. W. S. Adkins. Hazzard showed the Eagle crop out in Kinney County southeast of Chancellor, G. R. C., Reyment, R. A., and Tait, E. A., Ford as a threefold formation consisting of a Del Rio. Pessagno (1969) noted outcrops at 1977, Notes on lower Turonian ammonites from lower shaly member, a thinner middle mem- Loma el Macho, Coahuila, Mexico: Geological Sycamore Creek, Cow Creek, Pinto Creek, Institutions of University of Uppsala, Bulletin, n. ber of interbedded limestone and calcareous and Tequesquite Creek and that Texanites ser., v. 7, pp. 85–101. clay, and an upper shaly member. Freeman [Plesiotexanites] aff. T. stangeri densicostus Clark, D. L., 1963, The heteromorph Phlycticrioceras (1968, pp. 11–18) referred to the formation as was found at the last locality. Reeside (1932, in the Texas Cretaceous: Journal of Paleontology, the Boquillas Flags and recognized a four- pl. 4) illustrated a fragment of the Santonian v. 37, no. 2, pp. 429–432. fold division consisting of a basal pinch and Clark, D. L., 1965, Heteromorph ammonoids from ammonite Texasia dentatocarinata (Roemer) the Albian and Cenomanian of Texas and adjacent swell unit, a flagstone unit, a ledgy unit, from the Austin at Cow Creek, and Young areas: Geological Society of America, Memoir 95, and a laminated unit. The pinch and swell (1963, p. 120) recorded the species from 99 pp. unit yielded flattened fragments of Tar- Tequesquite Creek. Young also recorded Cobban, W. A., 1953a, Cenomanian ammonite fauna rantoceras sellardsi that suggest the middle Plesiotexanites shiloensis, Reginaites durhami, from the Mosby sandstone of central Montana: Cenomanian Acanthoceras amphibolum Zone, U.S. Geological Survey, Professional Paper 243–D, Bevahites bevahensis, and Submortoniceras pp. D45–D55, pls. 6–12. and one large but badly corroded ammo- tequesquitense from Tequesquite Creek and Cobban, W. A., 1953b, A new species of Prionocyclus nite that appears to be the late Cenomanian Texanites texanus from Cow Creek. The from Upper Cretaceous Carlile shale: Journal of Calycoceras (Proeucalycoceras) canitaurinum. holotype of Parapuzosia bosei Scott and Paleontology, v. 27, no. 3, pp. 353–355. Ammonites were not found in the overlying Moore came from Tequesquite Creek. Cobban, W. A., 1969, The Late Cretaceous ammo- flagstone unit, but the basal part of the ledgy nites Scaphites leei Reeside and Scaphites hippocre- pis (DeKay) in the western interior of the United unit (Hazzard’s interbedded limestone and States: U.S. Geological Survey, Professional Paper clay unit) contains the middle late Cenoma- Acknowledgments 619, 29 pp. nian Euomphaloceras septemseriatum fauna Cobban, W. A., 1972, New and little-known ammo- mentioned earlier in the present report. A We thank Glenn R. Scott (U.S. Geological nites from the Upper Cretaceous (Cenomanian specimen of Tarrantoceras (Sumitomoceras) Survey), Thomas W. Judkins (U.S. Geo- and Turonian) of the Western Interior of the Unit- conlini from this fauna was illustrated by logical Survey), and Neil H. Landman ed States: U.S. Geological Survey, Professional (American Museum of Natural History) Paper 699, 24 pp. (1971 imprint). Kennedy (1988, pl. 6, figs. 16, 17). Mammites Cobban, W. A., 1984, Mid-Cretaceous ammonite zones, was found near the top of the unit. for thoughtful and thorough reviews. Dee Western Interior, United States: Bulletin of the Geo- Freeman’s laminated unit contains Inoc- Ann Cooper (research fellow, nonvertebrate logical Society of Denmark, v. 33, pt. 1–2, pp. 71–89. eramus cf. dimidius in the lower half, which paleontology laboratory, Texas Natural Sci- Cobban, W. A., 1985, Ammonite record from Bridge suggests a very late middle Turonian age for ence Center, University of Texas at Austin) Creek Member of Greenhorn Limestone at Pueblo very graciously provided us with a preprint Reservoir State Recreation Area, Colorado: Society this part. A late Turonian age is indicated of Economic Paleontologists and Mineralogists, for the upper part of the unit by the pres- of the field trip guidebook to the geology of Field Trip Guidebook 4, 1985 midyear meeting, ence of Inoceramus perplexus, Nicaisolopha Big Bend National Park. Golden, Colorado, pp. 135–138.

August 2008, Volume 30, Number 3 Ne w Me x i c o Ge o l o g y 89 Cobban, W. A., 1987a, Ammonite faunas of the Cohee, G. V., chairman, 1961, Tectonic map of the Hirano, H., Tanabe, K., Ando, H., and Futakami, M., Sarten Sandstone (Cretaceous), Luna County, United States: U.S. Geological Survey and Ameri- 1992, Cretaceous forearc basin of central Hokkai- New Mexico: U.S. Geological Survey, Bulletin can Association of Petroleum Geologists, scale do; lithofacies and biofacies characteristics: 29th 1641–B, 17 pp. 1:2,500,000. International Geological Congress Field Trip CO2, Cobban, W. A., 1987b, The Upper Cretaceous ammo- Collignon, M., 1948, Ammonites néocrétacées du pp. 1–36. nite Eubostrychoceras Matsumoto in the Western Menabe (Madagascar). I. Les Texanitidae: Annales Hook, S. C., and Cobban, W. A., 1981, Late Green- Interior of the United States: U.S. Geological Sur- Géologiques du Service des Mines, no. 13, horn (mid-Cretaceous) discontinuity surfaces, vey, Bulletin 1690, pp. A1–A5. pp. 49–107; no. 14, pp. 5–101. southwest New Mexico; in Hook, S. C. (comp.), Cobban, W. A., 1988a, The Late Cretaceous ammo- Cooper, R. W., Cooper, D. A., Stevens, J. B., and Contributions to mid-Cretaceous paleontology nite Spathites Kummel & Decker in New Mexico Stevens, M. S., 2008, Geology of the Hot Springs and stratigraphy of New Mexico: New Mexico and Trans-Pecos Texas; in Contributions to Late Trail area, Ernst and San Vicente Members of Bureau of Mines and Mineral Resources, Circular Cretaceous paleontology and stratigraphy of New the Boquillas Formation; in Cooper, D. A. (ed.), 180, pp. 5–21. Mexico, Part 2: New Mexico Bureau of Mines and The southern extension of the Western Interior Hook, S. C., and Cobban, W. A., 1983, Mid-Creta- Mineral Resources, Bulletin 114, pp. 5–21. Seaway: Geology of Big Bend National Park and ceous molluscan sequence at Gold Hill, Jeff Davis Cobban, W. A., 1988b, Tarrantoceras Stephenson Trans-Pecos, Texas: 2008 Joint Annual Meeting of County, Texas, with comparison to New Mexico; and related ammonoid genera from Cenomanian the Geological Society of America and the Hous- in Hook, S. C. (comp.), Contributions to mid-Cre- (upper Cretaceous) rocks in Texas and the West- ton Geological Society, pp. 24–33. taceous paleontology and stratigraphy of New ern Interior of the United States: U.S. Geological Coquand, H., 1859, Synopsis des animaux et des Mexico, part II: New Mexico Bureau of Mines and Survey, Professional Paper 1473, 30 pp. végétaux fossiles observés dans la formation créta- Mineral Resources, Circular 185, pp. 48–54. Cobban, W. A.,1994, Diversity and distribution of cée du sud-ouest de la France: Société Géologique Hook, S. C., and Cobban, W. A., 2007, A condensed Late Cretaceous ammonites, Western Interior, de France, Bulletin, 2d ser., v. 16, pp. 945–1023. middle Cenomanian succession in the Dakota United States; in Caldwell, W. G. E., and Kauff- d’Orbigny, A., 1840-42, Paléontologie francais: Ter- Sandstone (Upper Cretaceous), Sevilleta National man, E. G. (eds.), Evolution of the Western Inte- rains crétacés, v. 1, Céphalopodes: Paris, V. Mas- Wildlife Refuge, Socorro County, New Mexico: rior basin: Geological Association of Canada, Spe- son, pp. 1–120 (1840), pp. 121-430 (1841), pp. 431– New Mexico Geology, v. 29, no. 3, pp. 75–99. cial Paper 39, pp. 435–451. 662 (1842). Cobban, W. A., and Hook, S. C., 1979, Collignoniceras Hyatt, A., 1903, Pseudoceratites of the Cretaceous, d’Orbigny, A., 1850-52, Prodrome de paléontolo- woollgari woollgari (Mantell) ammonite fauna from edited by T. W. Stanton: U.S. Geological Survey, gie stratigraphique universelle des animaux Upper Cretaceous of Western Interior, United Monograph 44, 351 pp. mollusques et rayonnés: Terrains crétacés, v. 2, States: New Mexico Bureau of Mines and Mineral Johnson, D. W., 1903, The geology of the Cerrillos Céphalopodes: Paris, V. Masson, 428 pp. Resources, Memoir 37, 51 pp. Hills, New Mexico; Part 2, palaeontology: School Daugherty, F. W., and Powell, J. D., 1963, Late Creta- Cobban, W. A., and Hook, S. C., 1980, Occurrence of of Mines, Quarterly, v. 24, pp. 101–174. ceous stratigraphy in northern Coahuila, Mexico: Ostrea beloiti Logan in Cenomanian rocks of Trans- Jones, B. R., and Reaser, D. F., 1970, Geology of American Association of Petroleum Geologists, southern Quitman Mountains, Hudspeth County, Pecos Texas; in Dickerson, P. W., Hoffer, J. M., and Bulletin, v. 47, no. 12, pp. 2059–2064. Callender, J. F. (eds.), Trans-Pecos region (west Texas; in Geology of the southern Quitman Moun- Fiege, K., 1930, Über die Inoceramen des Oberturon tains area, Trans-Pecos Texas: Society of Economic Texas): New Mexico Geological Society, Guide- mit besonderer Berücksichtigung der in Rheinland Paleontologists and Mineralogists, Permian Basin book 31, pp. 169–172. und Westfalen vorommenden Formen: Palaeonto- Section, Publication 70-12, pp. 1–24; also in Texas Cobban, W. A., and Hook, S. C., 1983, Mid-Creta- graphica, v. 73, pp. 31–47. ceous (Turonian) ammonite fauna from Fence Freeman, V. L., 1961, Contact of Boquillas Flags and Bureau of Economic Geology, 1970, Geologic Lake area of west-central New Mexico: New Austin Chalk in Val Verde and Terrell Counties, Quadrangle Map 39, scale 1:48,000, text. Mexico Bureau of Mines and Mineral Resources, Texas: American Association of Petroleum Geolo- Jones, T. S., 1938, Geology of Sierra de la Peña and Memoir 41, 50 pp. gists, Bulletin, v. 45, no. 1, pp. 105–107. paleontology of the Indidura formation, Coahuila, Cobban, W. A., and Kennedy, W. J., 1989, Acompsoce- Freeman, V. L., 1968, Geology of the Comstock– Mexico: Geological Society of America, Bulletin, ras inconstans zone, a lower Cenomanian marker Indian Wells area, Val Verde, Terrell, and Brewster v. 49, no. 1, pp. 69–150. horizon in Trans-Pecos Texas, U.S.A.: Neues Counties, Texas: U.S. Geological Survey, Profes- Kaplan, U., Kennedy, W. J., and Hiss, M., 2005, Jahrbuch für Geologie und Paläontologie Abhan- sional Paper 594-K, pp. K1–K26. Stratigraphie und Ammonitenfaunen des Campan dlungen, v. 178, no. 2, pp. 133–145. Gale, A. S., 1996, Turonian correlation and sequence im nordwestlichen und zentralen Münsterland: Cobban, W. A., and Kennedy, W. J., 1991, New stratigraphy of the Chalk in southern England; in Geologie und Paläontologie in Westfalen, no. 64, 176 pp. records of the ammonite Subfamily Texanitinae Hesselbo, S. P., and Parkinson, D. N. (eds.), Sequence Kaplan, U., Kennedy, W. J., and Wright, C. W., 1987, in Campanian (Upper Cretaceous) rocks in the stratigraphy in British geology: Geological Society, Turonian and Coniacian Scaphitidae from Eng- Western Interior of the United States; in Sando, Special Publication 103, pp. 177–195. land and north-western Germany: Geologisches W. J. (ed.), Shorter contributions to paleontology Geinitz, H. B., 1850, Das Quadersandsteingebirge Jahrbuch, Reihe A, no. 103, pp. 5–39. and stratigraphy: U.S. Geological Survey, Bulletin oder Kreidegebirge in Deutschland: Freiberg, Kauffman, E. G., Cobban, W. A., and Eicher, D. L., 1985, pp. B1–B4. (Germany), Craz & Gerlach, 292 pp. 1978, Albian through lower Coniacian strata, bio- Cobban, W. A., and Kennedy, W. J., 1993, Middle Haas, O., 1946, Intraspecific variation in, and ontog- stratigraphy and principal events, Western Interi- Campanian ammonites and inoceramids from the eny of, Prionotropis woollgari and Prionocyclus wyo- Wolfe City Sand in northeastern Texas: Journal of mingensis: American Museum of Natural History, or United States; in Événements de la partie moy- Paleontology, v. 67, no. 1, pp. 71–82. Bulletin, v. 86, art. 4, pp. 141–224. ene du Crétacé, Uppsala Nice 1975-1976: Annales Cobban, W. A., and Kennedy, W. J., 1994, Cenoma- Haas, O., 1949, Acanthoceratid Ammonoidea from du Muséum d’Histoire Naturelle de Nice, v. 4, nian (Upper Cretaceous) nautiloids from New near Greybull, Wyoming: American Museum of pp. 23.1–23.52 (1976 imprint). Mexico: U.S. Geological Survey, Bulletin 2073-E, Natural History, Bulletin, v. 93, art. 1, 39 pp. Kellum, L. B., and Mintz, L. W., 1962, Cenomanian pp. E1–E3. Hall, J., and Meek, F. B., 1856, Descriptions of fossils ammonites from the Sierra de Tlahualilo, Coa- Cobban, W. A., and Scott, G. R., 1973, Stratigraphy from the Cretaceous formations of Nebraska, with huila, Mexico: University of Michigan Museum and ammonite fauna of the Graneros Shale and observations upon Baculites ovatus and B. compres- of Paleontology, Contributions, v. 13, no. 10, Greenhorn Limestone near Pueblo, Colorado: U.S. sus, and the progressive development of the septa pp. 267–287. Geological Survey, Professional Paper 645, 108 pp. in Baculites, Ammonites, and Scaphites: American Kellum, L. B., Imlay, R. W., and Kane, W. G., 1936, (1972 imprint). Academy of Arts and Science, Memoir, new ser., Evolution of the Coahuila Peninsula, Mexico. Part Cobban, W. A., Hook, S. C., and Kennedy, W. J., 1989, v. 5, pp. 379–411. 1, Relation to structure, stratigraphy and igneous Upper Cretaceous rocks and ammonite faunas of Hancock, J. M., Kennedy, W. J., and Cobban, W. activity to an early continental margin: Geological southwestern New Mexico: New Mexico Bureau of A., 1994, A correlation of the upper Albian to Society of America, Bulletin, v. 47, pp. 969–1008. Mines and Mineral Resources, Memoir 45, 137 pp. basal Coniacian sequences of northwest Europe, Kennedy, W. J., 1984, Systematic palaeontology and Cobban, W. A., Merewether, E. A., Fouch, T. D., and Texas, and the United States Western Interior; in stratigraphic distribution of the ammonite faunas Obradovich, J. D., 1994, Some Cretaceous shore- Caldwell, W. G. E., and Kauffman, E. G. (eds.), of the French Coniacian: Palaeontological Associ- lines in the Western Interior of the United States; Evolution of the Western Interior basin: Geo- ation, Special Papers in Palaeontology 31, 160 pp. in Caputo, M. V., Peterson, J. A., and Franczyk, K. logical Association of Canada, Special Paper 39, Kennedy, W. J., 1988, Late Cenomanian and Turo- J. (eds.), Mesozoic systems of the Rocky Mountain pp. 453–476 (1993 imprint). nian ammonite faunas from north-east and cen- region, USA: Society for Sedimentary Geology, Hazzard, R. T., 1959, Diagrammatic stratigraphic tral Texas: Palaeontological Association, Special Rocky Mountain Section, pp. 393–413. section, Lozier Canyon sections, Terrell County, Papers in Palaeontology 39, 131 pp. Cobban, W. A., Walaszczyk, I., Obradovich, J. D., and Texas; in Cannon, R. L., and others (eds.), Geol- Kennedy, W. J., and Cobban, W. A., 1988, Mid-Turo- McKinney, K. C., 2006, A USGS zonal table for the ogy of the Val Verde Basin: West Texas Geological nian ammonite faunas from northern Mexico: Upper Cretaceous middle Cenomanian–Maastrich- Society, Field trip Guidebook 1950, p. 36. Geological Magazine, v. 125, no. 6, pp. 593–612. tian of the Western Interior of the United States Henderson, J., 1908, New species of Cretaceous Kennedy, W. J., and Cobban, W. A., 1990a, Cenoma- based on ammonites, inoceramids, and radiomet- invertebrates from northern Colorado: U.S. nian micromorphic ammonites from the Western ric ages: U.S. Geological Survey, Open-file Report National Museum, Proceedings, v. 34, no. 1611, Interior of the USA: Palaeontology, v. 33, pt. 2, 2006-1250, 46 pp. pp. 259–264. pp. 379–422.

90 Ne w Me x i c o Ge o l o g y August 2008, Volume 30, Number 3 Kennedy, W. J., and Cobban, W. A., 1990b, Rham- Kennedy, W. J., Cobban, W. A., Hancock, J. M., and (eds.), Lower and Middle Cretaceous terrestrial eco- phidoceras saxatilis n. gen. and sp., a micromorph Hook, S. C., 1989, Biostratigraphy of the Chispa systems: New Mexico Museum of Natural History ammonite from the lower Turonian of Trans- Summit Formation at its type locality; a Cenoma- and Science, Bulletin 14, pp. 39–55. Pecos Texas: Journal of Paleontology, v. 64, no. 4, nian through Turonian reference section for Trans- Lucas, S. G., Estep, J. W., Boucher, L. D., and Ander- pp. 666–668. Pecos Texas: Geological Institutions of the Univer- son, B. G., 2000, Cretaceous stratigraphy, bio- Kennedy, W. J., and Cobban, W. A., 1990c, The Mad- sity of Uppsala, Bulletin, n. ser., v. 15, pp. 39–119. stratigraphy and depositional environments near agascan ammonite Neogauthiericeras Collignon, Kennedy, W. J., Hancock, J. M., Cobban, W. A., and Virden, Hidalgo County, New Mexico; in Lucas 1969, from the Upper Cretaceous (Campanian) of Landman, N. H., 2004, A revision of the ammo- S. G. (ed.), New Mexico’s fossil record 2: New Texas: Paläontologische Zeitschrift, v. 64, no. 1/2, nite types described in F. Roemer’s “Die Kreide- Mexico Museum of Natural History and Science pp. 57–61. bildungen von Texas und ihre organischen Ein- Bulletin 16, pp. 107–119. Kennedy, W. J., and Cobban, W. A., 1991a, Coniacian schlüsse” (1852): Acta Geologica Polonica, v. 54, Mantell, G. A., 1822, The fossils of the South Downs, ammonite fauna from the United States Western no. 4, pp. 433–445. or illustrations of the geology of Sussex: London, Interior: Palaeontological Association, Special Lupton Relfo, 327 pp. Kennedy, W. J., Lindholm, R. C., Helmold, K. P., and Papers in Palaeontology 45, 96 pp. Martin, K. G., 1967, Stratigraphy of the Buda Lime- Hancock, J. M., 1977, Genesis and diagenesis of Kennedy, W. J., and Cobban, W. A., 1991b, Upper stone, south-central Texas: Society of Economic hiatus- and breccia-concretions from the mid-Cre- Cretaceous (upper Santonian) Boehmoceras fauna Paleontologists and Mineralogists, Permian Basin taceous of Texas and northern Mexico: Sedimen- from the Gulf Coast region of the United States: Section, Publication 67-8, pp. 287–290. Geological Magazine, v. 128, pt. 2, pp. 167–189. tology, v. 24, pp. 833–844. Matsumoto, Tatsuro, 1965a, A monograph of the Kennedy, W. J., and Cobban, W. A., 1993, Lower Klinger, H. C., and Kennedy, W. J., 1980, Cretaceous Collignoniceratidae from Hokkaido, Part 1: Cenomanian Forbesiceras brundrettei zone ammo- faunas from Zululand and Natal, South Africa. Kyushu University, Faculty of Science Memoirs, nite fauna in Texas, U.S.A.: Neues Jahrbuch für The ammonite subfamily Texanitinae Collignon, Series D, Geology, v. 16, no. 1, 80 pp. Geologie and Paläontologie Abhandlungen, 1948: Annals of the South African Museum, v. 80, Matsumoto, Tatsuro, 1965b, A monograph of the v. 188, no. 3, pp. 327–344. 357 pp. Collignoniceratidae from Hokkaido, Part 2: Kennedy, W. J., and Cobban, W. A., 2001, Campanian Klinger, H. C., and Kennedy, W. J., 1984, Cretaceous Kyushu University, Faculty of Science Memoirs, (Late Cretaceous) ammonites from the upper part faunas from Zululand and Natal, South Africa. Series D, Geology, v. 16, no. 3, pp. 209–243. of the Anacacho Limestone in south-central Texas: The ammonite subfamily Peroniceratinae Hyatt, Matsumoto, Tatsuro, 1969, Selected acanthoceratids Acta Geologica Polonica, v. 51, no. 1, pp. 15–30. 1900: Annals of the South African Museum, v. 92, from Hokkaido (Studies of the Cretaceous ammo- Kennedy, W. J., and Jagt, J. W. M., 1995, Lower pt. 3, pp. 113–294. nites from Hokkaido and Saghalien-XIX): Kyushu Campanian heteromorph ammonites from the Kummel, B., and Decker, J. M., 1954, Lower Turo- University, Faculty of Science Memoirs, Series D, Vaals Formation around Aachen, Germany, and nian ammonites from Texas and Mexico: Journal Geology, v. 19, no. 2, pp. 251–296. adjacent parts of Belgium and The Netherlands: of Paleontology, v. 28, no. 3, pp. 310–319. Matsumoto, Tatsuro, 1970, A monograph of the Col- Neues Jahrbuch für Geologie and Paläontologie Lamarck, J. B. P. A. de M. de, 1801, Système des lignoniceratidae from Hokkaido, Part 4: Kyushu Abhandlungen, v. 197, pt. 3, pp. 275–294. animaux sans vertèbres: Paris, J. B. P. A. de M. de University, Faculty of Science Memoirs, Series D, Kennedy, W. J., Cobban, W. A., and Hook, S. C., Lamarck, Chez Deterville, 432 pp. Geology, v. 20, no. 2, pp. 225–304. 1988a, Middle Cenomanian (Late Cretaceous) Lamolda, M. A., and Hancock, J. M., 1996, The San- Matsumoto, T., Noda, M., and Maiya, S., 1991, molluscan fauna from the base of the Boquillas tonian stage and substages: Bulletin de l’Institut Towards an integrated ammonoid-, inoceramid-, Formation, Cerro de Muleros, Doña Ana County, Royal des Sciences Naturelles de Belgique, Sci- and foraminiferal biostratigraphy of the Cenoma- New Mexico; in Contributions to Late Cretaceous ence de la Terre, v. 66 (Supplement), pp. 85–102. nian and Turonian (Cretaceous) in Hokkaido: paleontology and stratigraphy of New Mexico, Langenhan, A., and Grundey, M., 1891, Das Kies- Journal of Geography, v. 100, no. 3, pp. 378–398 Part II: New Mexico Bureau of Mines and Mineral lingswalder Gestein und seine Versteinerungen: (Japanese, English summary). Resources, Bulletin 114, pp. 35–44. Jahrbuch Glatzer Gebirges-Vereins, v. 10, 12 pp. Maxwell, R. A., and Dietrich, J. W., 1972, Geologic Kennedy, W. J., Cobban, W. A., and Hook, S. C., (Breslau). summary of the Big Bend region; in Geology of 1988b, Hourcquia Collignon, 1965 (Cretaceous Lasswitz, R., 1904, Die Kreide-Ammoniten von the Big Bend area, Texas: West Texas Geological Ammonoidea) from the upper Turonian of Texas: Geologische und Palaeontologisch Abhan- Society, Publication 72-59, pp. 11–33. the southern United States: Paläontologische dlungen, v. 10, pp. 223–259. Maxwell, R. A., Lonsdale, J. T., Hazzard, R. T., and Zeitschrift, v. 62, no. 1/2, pp. 87–93. Lehman, T. M., 1985, Transgressive-regressive cycles Wilson, J. A., 1967, Geology of Big Bend National Kennedy, W. J., Cobban, W. A., and Landman, N. H., and environments of coal deposition in Upper Park, Brewster County, Texas: University of Texas, 1997, Campanian ammonites from the Tombigbee Cretaceous strata of Trans-Pecos Texas: Gulf Coast Bureau of Economic Geology, Publication 6711, Sand Member of the Eutaw Formation, the Moore- Association of Geological Sciences, Transactions, 320 pp. ville Formation, and the basal part of the Demopolis v. 35, pp. 431–438. Meek, F. B., 1871, Preliminary paleontological Formation in Mississippi and Alabama: American Lehman, T. M., 1986, Late Cretaceous sedimentation report, consisting of lists of fossils, with descrip- Museum Novitates 3201, 44 pp. in Trans-Pecos Texas: West Texas Geological Soci- tions of some new types, etc.: U.S. Geological Sur- Kennedy, W. J., Cobban, W. A., and Landman, N. ety, Bulletin 25, no. 7, pp. 4–9; also in Pausé, P. H., vey of Wyoming (Hayden), Preliminary Report H., 2001, A revision of the Turonian members and Spears, R. G. (eds.), 1986, Geology of the Big v. 4, pp. 287–318. of the ammonite Subfamily Collignoniceratinae Bend area and Solitario dome: West Texas Geo- Meek, F. B., 1877, Paleontology: U.S. Geological from the United States Western Interior and Gulf logical Society, 1986 field trip, Publication 86-82, Exploration of the Fortieth Parallel (King), v. 4, Coast: American Museum of Natural History, Bul- pp. 105–110. pp. 1–197. letin 267, 148 pp. Lehman, T. M., and Tomlinson, S. L., 2004, Terlin- Merewether, E. A., Tillman, R. W., Cobban, W. A., Kennedy, W. J., Juignet, P., and Girard, J., 1990, guachelys fischbacki, a new genus and species of and Obradovich, J. D., 1988, Outcrop sections of Budaiceras hyatti (Shattuck, 1903), a North Ameri- sea turtle (Chelonoidea): Protostegidae from the the Upper Cretaceous Frontier Formation, south- can index ammonite from the lower Cenomanian Upper Cretaceous of Texas: Journal of Paleontol- eastern Bighorn Basin, Wyoming; in Keefer, W. R., of Haute Normandie, France: Neues Jahrbuch für ogy, v. 78, no. 6, pp. 1163–1178. and Goolsby, J. E. (eds.), Cretaceous and lower Geologie and Paläontologie Monatshefte, 1990, Logan, W. N., 1899, Contributions to the paleontol- Tertiary rocks of the Bighorn Basin, Wyoming no. 9, pp. 525–535. ogy of the Upper Cretaceous series: Field Colum- and Montana: Wyoming Geological Association, Kennedy, W. J., Walaszczyk, I., and Cobban, W. A., bian Museum Publication 36, Geological Series, Guidebook 49, pp. 31–42. 2000, Pueblo, Colorado, USA, candidate Global v. 1, no. 6, pp. 201–216. Miller, A. K., and Youngquist, W., 1946, A giant Boundary Stratotype Section and Point for the Lonsdale, J. T., Maxwell, R. A., Wilson, J. A., and ammonite from the Cretaceous of Montana: Jour- base of the Turonian Stage of the Cretaceous, and Hazzard, R. T., 1955, Geology of Big Bend Nation- nal of Paleontology, v. 20, no. 5, pp. 479–484. for the base of the middle Turonian Substage, al Park: West Texas Geological Society, Guide- Molenaar, C. M., 1983, Major depositional cycles and with a revision of the Inoceramidae (Bivalvia): book, 1955 Spring Field Trip, pp. 19–126. regional correlations of upper Cretaceous rocks, Acta Geologica Polonica, v. 50, no. 3, pp. 295–334. Lovejoy, E. M. P., 1976, Geology of Cerro de Cristo southern Colorado Plateau and adjacent areas; in Kennedy, W. J., Walaszczyk, I., and Cobban, W. A., Rey Uplift, Chihuahua and New Mexico: New Reynolds, M. W., and Dolly, E. D. (eds.), Mesozoic 2005, The global boundary stratotype and point Mexico Bureau of Mines and Mineral Resources, paleogeography of west-central United States: for the base of the Turonian Stage of the Creta- Memoir 31, 82 pp. Society of Economic Paleontologists and Miner- ceous, Pueblo, Colorado, U.S.A.: Episodes, v. 28, Lozo, F. E., Jr., 1951, Stratigraphic notes on the Man- alogists, Rocky Mountain Section, pp. 201–224. no. 2, pp. 93–104. ess (Comanche Cretaceous) shale; in Lozo, F. E., Moon, C. G., 1953, Geology of Agua Fria quadran- Kennedy, W. J., Wright, C. W., and Hancock, J. M., Jr. (ed.), The Woodbine and adjacent strata of the gle, Brewster County, Texas: Geological Society of 1980, Origin, evolution and systematics of the Waco area of central Texas: Fondren Science Series America, Bulletin 64, pp. 152–195, also in Univer- Cretaceous ammonoid Spathites: Palaeontology, 4, pp. 65–92. sity of Texas, Bureau of Economic Geology, Report v. 23, pt. 4, pp. 821–837. Lucas, S. G., and Estep, J. W., 1998, Lithostratigraphy of Investigations 15. Kennedy, W. J., Wright, C. W., and Hancock, J. M., and biostratigraphy of the Lower-Middle Creta- Morrow, A. 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August 2008, Volume 30, Number 3 Ne w Me x i c o Ge o l o g y 91 Passy, A., 1832, Description géologique du dépar- Sowerby, J., 1818-1820, The mineral conchology of (ed.), Treatise on invertebrate paleontology, Part L. tament de la Seine-Inférieure: Rouen, Imprimerie Great Britain: London, B. Meredith, v. 3, 1818, Mollusca 4, v. 4, 362 pp. Nicétas Periaux, 371 pp. pp. 1–40; 1819, pp. 41-98; 1820, pp. 99–126. Wright, C. W., and Kennedy, W. J., 1981, The Pessagno, E. A., Jr., 1969, Upper Cretaceous stratig- Stephenson, L. W., 1953, Larger invertebrate fos- Ammonoidea of the Plenus Marls and the Middle raphy of the western Gulf Coast area of Mexico, sils of the Woodbine Formation (Cenomanian) of Chalk: Palaeontographical Society, Monograph, Texas, and Arkansas: Geological Society of Amer- Texas: U.S. Geological Survey, Professional Paper 148 pp. ica, Memoir 111, 139 pp. 242, 226 pp. (1952 imprint). Wright, C. W., and Kennedy, W. J., 1984, The Powell, J. D., 1961, Stratigraphy of Cenomanian– Stephenson, L. W., 1955, Basal Eagle Ford fauna Ammonoidea of the Lower Chalk: Palaeontographi- Turonian (Cretaceous) strata, northeastern Chi- (Cenomanian) in Johnson and Tarrant Counties, cal Society, Monograph, Part 1, 126 pp. huahua and adjacent Texas: Unpublished Ph.D. Texas: U.S. Geological Survey, Professional Paper Wright, C. W., and Kennedy, W. J., 1994, Evolution- dissertation, University of Texas, Austin, 46 pp. 274-C, pp. 53–67. ary relationships among Stoliczkaiinae (Creta- Powell, J. 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