AN OVERVIEW OF THE TERRESTRIAL EARLY TERTIARY OF SOUTHERN NORTH AMERICA- FOSSIL SITES AND PALEOPEDOLOGY
JUDITH A. SCHIEBOUT DEPARTMENT OF GEOLOGY LOUISIANA STATE UNIVERSITY
ABSTRACT would have suggested. Evidently, neither Increasingly detailed stratigraphic work the slow-to-open North Atlantic nor the in intermontane basins from Montana to long distances were insurmountable bar Texas has revealed significant differences riers to many mammals before the end of between northern and southern early Ter the early Eocene. The Cretaceous interior tiary terrestrial faunas of western North seaway split North America and served as America. Paleontological data from south a barrier to migration between west and ern California, Mexico, New Mexico, and east Texas. The effects of this separation west Texas allows analysis of the effects of may have lingered throughout the Pale topography and climate on southern faunal ocene. distribution. Endemism in the Paleocene and Eocene of southern California and the INTRODUCTION Paleocene of west Texas can be attributed in part to geographic isolation. Observed Several recent developments make this differences between northern and south a good time to look both backwards and ern faunas are tied to climatic differences, forwards at the terrestrial Paleocene and which are traceable from locality to locali Eocene of southern North America. Are ty using paleopedology. For example, Pa vision of terrestrial Cenozoic chronology edited by M.O. Woodburne is in prepara leocene fluvial mudstones in west Texas and New Mexico show prominent red and tion and should be published within 1979 or 1980 (Woodburne, 1978, pers. comm.). black banding. Red layers are rich in soil Although many aspects of this summing up formed calcite nodules. Red color-banding of available data on Cenozoic chronology and nodules are not widespread in north will be highly controversial, it should serve ern localities until the early Eocene, indi as a reference point for decades, as tts cating a northward spread of warm, vari predecessor by Wood et al. (1941) did. A able climate. Migrations of animals, trig great deal of new stratigraphie data has gered by such climatic changes, may be become available recently. Detailed strati responsible for abrupt faunal changes m graphic studies such as those of Gingerich the northern intermontane basins. (1976) are making possible a much greater Early Tertiary fossil vertebrate sites are precision in examining past evol~bonary scarce east of the Big Bend region of Texas and paleoecologic events. New datmg and now but within a decade lignite strip min fossil-collecting techniques and changes m ing in east Texas, Louisiana, and Arkan the legal status of pre-Pleistocene fossils sas will be producing outcrops. The best also provide an increasingly detailed back hope for fmding extensive early Terltary ground against which attempts can be terrestrial faunas in eastern North Amen made to correlate paleontological data on ca lies in the Gulf Coast. animal distributions with information on The early Tertiary Gulf Coast may have small scale environmental changes, ~vail served as a source for new forms migrat able from studies of depositional environ ing to the west and north. The Paleocene ments and paleopedology. and early Eocene faunas of the southeast ern U. S. can be expected to have strong ADVANCES IN European affinities, and the late Eocene to TERRESTRIAL PALEONTOLOGY have close ties to western North Amenca. Screen washing for microvertebrat: The Paleocene faunas of west Texas show f~s sils (Hibbard, 1949; McKenna, 1962) IS m less resemblance to those of France, which creasing the value of vertebrate fossils as were similar in latitude, than the high de stratigraphic tools. It greatly mcrease~ gree of similarity of early Eocene animals sample sizes and recovers rare matena of Europe and western North Amenca 75 76 Tulane Studies in Geology and Paleontology Vol. 15 from sediments essentially barren to sur migration route (see summary of Berg face hunting and quarrying. For example, gren et al., 1978). a screen washing of approximately one ton Both problems and opportunities arise of sediment from a single Paleocene site in from changes in the legal status of verte west Texas yielded 19 genera (Schiebout, brate fossils and from extensive mining 1974), three times the total previously and other disturbances that will affect known from the whole formation (Wilson, early Tertiary terrestrial deposits more 1967). New techniques of sorting fossils and more frequently in the future. A de from concentrate (screen wash residue), bate is underway between federal officials such as the heavy liquid method reported and the paleontological community regard by Murray and Lezak (1977), will make ing the applicability of such legislation as this technique more and more useful. the Antiquities Act of 1906, the National New dating techniques and increasing Environmental Protection Act, and the application of old ones are producing a Moss-Bennett Bill to those paleontological more reliable framework for reconstruc materials not associated with anthropologi tion of early Tertiary events. For example, cal or archaeological material. The Nation radiometric dating of volcanic rocks in al Heritage Act of 1972 specifically includes tercalated with vertebrate-bearing sedi paleontological materials for protection, ments is producing better resolution of the and new legislation specifically aimed at age of many classic sites. A magnetic re providing salvage procedure for such fos versal scale for the terrestrial early Terti sils can be expected in a few years (Me ary is also being developed (Berggren et Kinney, 1978, pers. comm.). Marshall (1976) al., 1978; Lindsay et al. , 1978). provided a review of the legal status of pa Widespread acceptance of the idea of leontology in the U.S. at that time. plate tectonics has revolutionized paleo At present, regulation often means that geography and spurred interaction of pa scientists and conscientious amateurs are leocologists in testing reconstruction of excluded from areas where vandals and continental positions and latitudes. The re ill-trained amateurs continue to roam at cent work of Dawson et al. (1976) and West will. As the historical, scientific, and aes et al. (1977) in the Eureka Sound Forma thetic values of vertebrate fossils are grad tion of Ellesmere Island is an example of ually communicated to the bureaucracy "continental drift" providing incentive for responsible for regulating antiquities, bet investigation of a new and unusual area ter cooperation between government agen for vertebrate fossils. Drift theory and pa cies and scientists should develop. As pale leobotanical evidence had led McKenna ontologic remains come to be regarded as (1972a, 1972b, 1972c, 1975) to consider an a natural resource, they can no longer be early Tertiary North Atlantic migration blithely ignored by miners and land devel route for terrestrial animals between North opers. Availability of funds for survey and America and Europe. Dawson et al. (1976) salvage, long a boon to archeologists, is reported a small Eocene fauna of verte beginning to extend to paleontologists. An brates which supports the idea that a example is the Bureau of Land Manage warm temperate climate extended to 80° ment-sponsored survey in 1977 by the north latitude. A symposium entitled "Cen University of New Mexico and Louisiana ozoic History in and around the northern State University of 41/2 million acres of land Atlantic and Arctic Oceans" at the 1978 in the San Juan Basin (Kues et al. , 1977). Geological Society of America Annual Cretaceous and early Tertiary paleonto Meeting drew workers interested in recon logic resources threatened by coal strip structing early Tertiary conditions in this mining were the specific target of the region from a wide variety of disciplines. study (Fig. 2). Opportunities for employ The early Eocene (Wasatchian) mammali ment for paleontologists, particularly ver an faunas of North America show at last tebrate paleontologists, with governmental 50o/o generic similarity to those of Europe; agencies and industry are likely to increase such similarity is not repeated again and in the future and museums can expect drops to 10o/o in the Bridgerian (Dawson et large, sometimes overwhelming, increases al. , 1976), suggesting that this marks the in specimens recovered in salvage work. severance of the North America-to-Europe A concurrent flood of new data on the No. 3 Terrestrial Early Tertiary 77
7•
Figure 1. Index Map to Paleontological and Paleopedological Localities. Paleocene: 1, G?ler Format~on locahty; 5, San Diego County; 6, Punta Prieta; 9, San Juan Basin ; 14, Big Be nd NatiOnal Park; 16, Caddo Parish. Eocene: 2 & 3 Ventura Basin· 4 Carlsbad· 5, ~an Diego; 7, Guanajuato; 8, Parras and La Popa B~sins; 9 San Ju;n Basin ; 10: Galisteo Formation locality; 11, Baca Formation locality; 12, Vieja; 13, Agua Fria; 14, Big Bend Nationa l Park; 15, Laredo; 17, Clark County; 18, Little Stave Creek; 19, Twiggs County. early Tertiary of North American can also well-known rock units and the names re be expected. main a link to western history. The redefi A fossil "gold rush" in the last quarter of nition now in progress should bring use of the 19th century set the stage fo r modern these terms more into line with modern work on the terrestrial early Tertiary of stratigraphic practice. From oldest to North America. Deposits that are still con youngest, the Paleocene is divided into the sidered the best terrestrial fossil-bearing following Land Mammal Ages: Puercan, Paleocene and Eocene sites in the world Torrejonian, and Tiffanian. The Eocene is were discovered in the Ame rican west, divided into the Wasatchian, Bridgerian, a nd fo ssils stream ed back from Wyoming, Uintan and Duchesnean. Some specialists Colorado, and New Mexico, to eastern consider the Clarkforkian wholly Eocene museum s. The Cope-Marsh feud raged, and others partly Paleocene and partly leaving a legacy of over-split early Tertiary Eocene. Future papers on its placement taxa. The concepts of the North American can be expected shortly (Sloan, 1978, pers. Land Mammal Ages of the Paleocene and comm.: Gingerich, 1978, pers. comm.). Eocene , which are currently in use, devel PALEOCENE AND EOCENE oped through work on the fossils pre PALEOCLIMATE se rve d in the intermonta ne basins of Wy oming, Colorado, a nd New Mexico. Wood The emerging large-scale picture of et al. (1941) a ttempted to standardize these North American Paleocene and Eocene subdivisions as biostra tigraphic units but paleoclimate is a synthesis of many lines of the d e finitions of many remained tied to evidence. Frakes and Kemp (1972) sum- 78 Tulane Studies in Geology and Paleontology Vol. 15
Figure 2. Skull of Claenodonferox in place as discovered in the Naciemiento Formation on the 1977 paleontological survey in the San Juan Basin. Specimen is approximately 13 em long. Photo by A. K. Schrodt.
marized information on Paleocene and Eo with data on paleogeography. For ex cene climate worldwide and integrated it ample, Miocene Basin-and-Range faulting with plate tectonic data. Wolfe (1978) pro produced generally north-south trending vided a summary of foliar physiognomy ranges that isolated parts of the American data in tracing North American Tertiary southwest from moisture-bearing winds large scale climatic changes, which he at and produced a degree of aridity not seen tributes to changes in the earth's inclina in the early Tertiary. The lack of polar ice tion. Paleobotanical data derived from caps, considered by Sevin (1975) to have palynology and the study of leaf form, and formed in the Miocene, would also have paleontological data derived from a slowly produced a less latitudinally-stratified early developing picture of animal migrations Tertiary climate in which the subtropical and from the ranges of animals with tem conditions postulated for Ellesmere island perature-limited distributions, such as could fit. crocodiles and alligators, must be joined Work by Sloan (1969) and Van Valen No. 3 Terrestrial Early Tertiary 79 and Sloan (1977) has documented early northern and southe rn faunas are known Tertiary animal distribution patterns, which to have shifted. The San Juan Basin Pale may have been climate-controlled. Sloan ocene and Eocene faunas are among the (1969) recognized distinctive northern and best known southern early Tertiary de southern Paleocene faunas separated by posits of North America. They, and depos an east-west line running through south its further south both east and west of the ern Wyoming. A large Paleocene fauna Paleocene continental divide, can serve to from Trans-Pecos Texas, the southern characterize southern sites and associated most large assemblage of mammals of this paleopedological climatic indicators. age from North America, agrees with Information on paleopedology is begin some of his generalizations (Schiebout ning to be used in conjunction with paleon 1974, p. 44). New information suggests that tological data to reconstruct local climates the continental divide may have shifted for individual Paleocene vertebrate locali from west to east of the San Juan Basin in ties. Soil-formed color banding in over the Tiffanian (Sloan, 1977, pers. comm.) so bank mudstones has been recognized as a that elements previously considered "north climate indicator by vertebrate paleontolo e rn" in the west Texas fauna may in reali gists for over 60 years. Sinclair and ty be due to both faunas being east of the Granger (1911, p. 116-117) considered color divide. This could explain puzzling differ banding in mudstones in the Eocene and e nces between the P aleocene faunas of Oligocene of the Wind River and Bighorn west Texas and the San Juan Basin, 850 basins to be a result of recurring moist and kilometers a way. Van Valen and Sloan arid climatic cycles. Color banding has (1977) considered the shift in faunas mark been used to reconstruct details of temper ing the Cretaceous-Tertiary boundary in ature and rainfall for individual early Ter Montana to be the result of a shift south tiary paleontological sites only in the last ward of temperate coniferous forest dis decade (Schiebout, 1970, 1974, 1978; Bown, placing subtropical deciduous ones. Savin 1975, 1977). For example, Schiebout (1970, (1975) provided oxygen isotope data for 1974), working in the Paleocene of West late Cretaceous cooling; McLean (1978) Texas, described color banding in over postulated a brief, intense warm spell at bank muds of the fluvial Black Peaks For the Cretaceous-Tertiary boundary. The mation as indicative of alternating wet and fauna that m arks the base of the Eocene in dry post-depositional conditions of greater the well-studied northern intermontane than seasonal duration in a semitropical to basins is considered to have shifted in re tropical climate (Fig. 3). Red bands rich in sponse to a northward spread of subtropi soil-formed microcrystaline calcium car cal climates after a warm temperate inter bona te nodules developed during dry peri val in the Tiffanian (Sloan, 1969). Gingerich ods when flood-deposited alluvium dried (1977, p. 497) discussed the correlation be out and water ta bles were low. Black tween major climatic warming periods layers, colored by organic matter, formed seen in the early Eocene, early Oligocene , in wet periods when the water table stayed early Miocene, and early Pliocene, and at or above the alluvial surface, producing high latitude intercontinental migration reducing conditions. During these pe riods, such as tha t noted between North America the floodplain may ha ve resembled parts and Europe in the Wasatchian. Estes of the modern Amazon Basin (Sioli, 1951, (1976) briefly discussed the effect of early p. 279) and the Atchafalaya Basin of Loui Tertiary climatic shifts on the lower verte siana where heavy forests grow in stand brates of North America. ing water. According to Van Houten ( 1948, 1973), discussing North American early No single fixed north-south geographic Tertiary banded beds, recently-depos1ted barrier is known for the early Tertiary of a lluvium would have been drab, probably the American west. The northern extent brownish in color and the eventual red of the San Juan Basin of new Mexico and color would have been a result of dehydra Colorado has been selected as the north tion of inherited iron oxides plus in-place ern boundary delineating the "south" for oxidation of iron-bearing minerals in the the purposes of detailed discussion of sites floodplain soils. Gray zones and mottled in this paper. No single line could separate areas were the product of reduction. all northern and southern features, and Vol. 15 80 Tulane Studies in Geology and Paleontology
bonate availability may greatly modify the time needed to form nodules and the range of climates in which they can form. The color bands are not facies indicators as such because they are post-depositional features. Regional climatic factors, includ ing amount and periodicity of rainfall and annual temperature means and ranges, af fect the pattern of ground water changes, as do local features such as avulsions. Both banding and the formation of nodule rich zones would be affected by geomor phology, i .e., floodplain relief. Schumm (1968, 1977) assigned a major role in fluvial geomorphology to stabilization of flood plains by vegetation, which is strongly af fected by climate. Results of local tecton ism may eventually become clearly under stood for the sites discussed in the remain der of this paper, allowing recognition of small scale climatic changes.
SITES OF THE SOUTHWEST Paleocene and Eocene localities of south ern North America will be considered in an effort to extract faunal and paleopedo logical clues concerning the factors con trolling the faunal character of the south, in this section and the following one. Lo Figure 3. Color banding in mudstone of calities will be considered roughly in se the Paleocene Black Peaks Formation quence from the west where data is mod in Big Bend National Park, Texas. Two erately abundant to the east where it is red layers are separated by light gray very sparse. For a discussion of all North layers from a prominent black band American Paleocene localities see Russe ll (arrow). Meter stick for scale. (1967). Figure 1 gives localities discussed in the following sections. The presence of calcium carbonate nod ules is becoming widely recognized as an California indicator of semiaridity (Steele, 1974; Me The only Paleocene mammalian re Bride, 1974, 1975; Pierce and Peterson, mains from southe rn California constitute 1975). According to Freytet (1973), nodule the Laudate faunule from the Coler For formation occurs in the zone of oscillation mation (Fig. 1, no. 1). The 2000-meter-thick of a phreatic water table. Cracks, narrow Coler Formation has yielded only three ing toward the outside of the nodule, are identifiable mammal tee th. According to common in nodules of the west Texas Pa M'CK_enna (1960) they belong to three spe leocene. The cracks indicate wetting and cies, only one of which can unquestionably drying, and thus are consistent with Frey be referred to a previously known genus. let's model of nodule formation. The exact The faunule is possibly Torrejonian in age. role of calcium carbonate availability in According to McKenna (1960), the location nodule formation remains to be clarified. of the Laudate fa unule west of the Paleo For example, thick P leistocene caliches in cene continental divide accounts for its the J ornada Basin of New Mexico are at containing two genera not know n from tributed by Seager and Hawley (1973) to further east and one which may have been leaching of abundant wind-deposited car present in California be fore its dispersal bonate dust from upper soil layers. Car- eastward. No.3 Terrestrial Early Tertiary S l
F igure 4. An Eocene (Uintan) site in San Diego County, California. Students from San Diego State University collect fossil mammals from gray mudstone of the Mission Valley Formation. To the north, Jurassic rocks form highlands as they did in the Eocene.
West of the San Andreas fault system in Three areas of exposure of mammal San Diego County (Fig. 1, no. 5) , red pale bearing terrestrial Eoce ne rocks are avail osols developed on Jurassic and Cretace able from southern California. Exposures ous rocks. They underlie Eocene mammal in San Diego County (Fig. I, no. 4,5) are bearing rocks, which have been intensive fl uvial and alluvial fan coastal deposits in ly studied. They have been interpreted as tertonguing with marine rocks. These laterites, probably Paleocene with a possi rocks have provided a rare opportunity for bility that some may be late Cretaceous or comparison of the terrestrial biostrati early Eocene, by Peterson and Abbott graphic chronology with the marine micro (1975) and Abbott et al. (1976). These in fossil and megafossil subdivisions of the vestigators consider the paleosols indica Eocene. Fluvial, alluvial fan, and lacustrine tive of a humid tropical climate with great deposits of the Ventura Basin to the north e r than 120 em annual rainfall, a climate filled an east-west trending trough (Golz, warmer than the Eocene climate and the 1976, fig. 1). Recent work on the Eocene of modern climate of the area. These paleo southern California, including a salvage sols certainly indicate a climatic difference program in San Diego County under the from that under which the overlying Eo direction of Jason A. Lilligraven, has pro cene rocks accumulated because the latter duced a sequence of papers on these Uintan lack the striking red color. Movement on deposits (Fig. 4). Several authors have the San Andreas fault may have been as found evidence of endemism in Southern much as 200 km, so that climatic conclu California Eocene faunas. ManJ species of sions based on the laterite or on the over Artiodactyls not known from deposits fur lying Eocene deposits must be considered ther east indicate the presence of geologic as applying to lower latitudes in Mexico and ecologic barriers encouraging specia during the Paleocene. tion accordinr, to Golz (1 976). The far Vol. 15 82 Tulane Studies in Geology and Paleontology smaller collection of San Diego County Cretaceous-Paleocene Difunta Group in perissodactyls also shows some evidence these basins are rich in red or reddish of endemism (Schiebout, 1977). Black and brown mudstones, which contain abundant Dawson (1965) considered small rodents soil-formed nodules. The red color is caused and primates to indicate endemism, but by post-depositional oxidation during dry small reptiles do not, according to Schatz seasons, induced by strong seasonal aridi inger (1975). Lillegraven's (1976) study of ty, when the water table was low in an small insectivores suggested that a contm overall warm subhumid to semiarid climate uous forest cover was available from San (McBride et al., 1975, p. 497). Caliche nod Diego County eastward to sites in the ules are particularly common in coarse Rocky Mountains and high plains. A pos material topping upward-coarsening se sible explanation for endemism in some quences interpreted as caused by gradual groups and not in others could li e in local filling of lakes and swamps (McBride, 1975, climate, clues to which lie in the paleosols. p. 499-500). An Eocene vertebrate site in Unlike the older underlying rocks, middle western Mexico at Guanajuato has yielded and late Eocene rocks of San Diego County two rodents and a tapir forelimb from a lack red color but are rich in microcrystal site having red sediment (Fries et al. , 1955; line calcium carbonate nodules. Pierce and Black and Stephens, 1973; Ferrusquia, Peterson (1975, p. 75 ) postulated a change 1978). in climate from the older, hot, humid con ditions (temperature 20-25°C, rainfall over New Mexico 120 em) to warm semiarid conditions (38-64 The concept of the Paleocene developed em of rainfall) with a pronounced dry sea through studies of North American west son. Some animals could have been con ern intermontane deposits, and none fined to riparian forests and others could played a greater role than those of the San have ventured into drier interfluvial areas. Juan Basin in northwestern New Mexico Endemism seems most pronounced in and adjacent Colorado (Fig. 1, no. 9). The those animals that would range beyond Puercan and Torrejonian Land Mammal small forest belts. On the whole, the Cali Ages were originally defined on San Juan fornia Paleocene and Eocene data sug gests that local microclimatcs and Lara Basin mammal sites and faunas. Paleocene mide uplifts could have had major effects sites in the San Juan Basin number in th e on early Tertiary mammal distributions. hundreds, and fossils from these localities are housed in many of the major museums of North America. Salvage work in the Mexico mainly fluvial Nacimiento Formation, A fossil locality from Baja California (Fig. made necessary by strip mining of coal con I, no. 6) is the southernmost site yielding tained in the underlying Cretaceous Kirt Paleocene mammals from North America. land a nd Fruitland Formations, can be ex Like other sites lying west of the San peeled to greatly increase our knowledge Andreas Fault zone, it surely lay further of Paleocene faunas in this area. Overbank south at the time of deposition. The locali mudstones of the Nacimiento (Fig. 5) and ty has yielded a barylambdid pantodont, San Jose Formations show prominent Esthonyx, and a primitive Hyracotherium, color banding with bright red beds becom and is a pproximately Tiffanian in age ing more common upsection (Simpson, (Morris, 1968; Ferrusquia, 1978). 1948, 1950). In the Nacimiento Formation Mexican Paleocene and Eocene paleosols red bands are rare in sediments bearing east of the San Andreas Fault Zone give Puercan faunas but common in some sedi indications of the early Tertiary climate ments bearing Torrejonian fossils, while that are valuable for comparisons to the rare in others (Simpson, 1950). Soil-formed vertebrate-bearing localities lying in inter calcium carbonate nodules are locally montane basins to the north. In the Late common. According to Simpson (1948, p. Cretaceous and Paleocene, the Parras and 368-369), the banded mudstones of the La Papa basins of northeast Mexico re uppe r portion of the San Jose Formation ceived approximately 6000 m of terrigen contain more red beds and are brighte r in ous sediment (McBride et al. , 1975 , p. 1663). color, in general, than those of the lower The delta plain sediments of the Upper San Jose Formation. No.3 Tenestrial Early Tertiary 83
...... ·- - F igure 5. Two prominent red mudstone layers (arrow) at Barrel Springs, co-typical area for the TorreJOruan Land Mammal Age of the Paleocene. Nacimiento Formation of the San Juan Basin.
Preliminary study of Eocene fossils of Texas the San Jose Formation, which overlies Work by John A. Wilson and colleagues the Nacimiento F ormation in the San Juan in three areas of Trans-Pecos Texas has Basin, fossils from the Galisteo Formation uncovered the southernmost large early exposed in the Rio Grand Valley, (Fig. 1, Tertiary mammal faunas known from no. 10) and fossils from the Baca Forma North America. The Vieja and the Agua tion of central western New Mexico, (Fig. Fria areas have yielded Eocene fossils; 1, no. 11) is underway. The San Jose For Big Bend National Park has yielded both mation contains Wasatchian vertebrates Paleocene and Eocene sites. Work is in (Simpson, 1948), and is currently yielding progress by Testamada on magnetic re specimens from new sites (Lucas, 1977, versal chronology of the Trans-Pecos vol pers. comm.). The Galisteo Formation has canic field (Wilson, 1978, pers. comm. ). yielded a few fossils indicating a possible Color banding and calcareous nodules age range from Wasatchian to Duchesnean characterize the overbank deposits of fluv (Stearns, 1943; Robinson, 1957; Mellett, ial rocks of Maestrichtian to Wasatchian 1976). Stearns (1943) interpreted the color age in Big Bend National Park (Wilson, banding in the Galisteo Formation, includ 1967; Schiebout, 1974; Lawson, 1972!. Late ing red bands, as formed in a warm cli Cretaceous and early Tertiary rocks m the mate with variable rainfall. The Baca For park were subdivided by Maxwell et al. mation ranges in age from late Cretaceous (1967) into the Javelina Formation, which to early Oligocene. Rocks containing Bridg contains Maestrichtian dinosaurs and pter erian fossils in the Baca Formation north osaurs (Lawson, 1972), the Black Peaks of Datil are interbedded with red mud Formation, which contains Tiffanian to stone rich in soil-formed carbonate nod Clarkforkian mammalian faunas (Fig. 6; ules. The Galisteo and the Baca Formation Schiebout, 1974), and the Hannold Hill are both capped with volcanic rocks, re Formation, which has yielded a Wasatchi cording the onset of local volcanism. an fauna (Wilson, 1967). Some typically Vol. 15 84 Tu lane Studies in Geology and Paleontology
F igure 6. Sinkhole in color banded fl uvial mudstone of the P aleocene Black P eaks For mati on. Microcrystalline calcium carbonate nodules are abundantly visible on eroded surfaces and in the scree in the foreground.
Torrejonian taxa are present in the Black closely contemporary to floras of the P ale· Peaks Formation, but the Pue rcan faunas ocene T ullock and Lebo F ormations, and as found in the San Juan Basin a re a bsent conclud ed that it li ved under a climatic or at last have not been recovered. The regime of therm al equability and seasonal Canoe Formation, w hi ch marks the begin p recipitation. ning of local tectonic acti vi ty in the Big Eocene fossil-bearing sites in the Vieja Bend region, contains a sparse, possibly area of west Texas (Fig. 1, no. 12) have re Bri dgeri a n, mammal fauna (Wilson, 1967). ceived compre he nsive treatment in a paper The Canoe Formation includes coarse con by Wilson (1977). The Vieja fa unas have glomerates, unlike the unde rl ying de posits. been published in several systematic works including Wilson (197la, b ; 1974, 1977), Wil P aleobotanical evidence substantiates son and Szalay (1976), F orsten (197la,b) climatic variability as partially responsible Ha rris (1967), McGrew (1971 ), Wood (1974 for the color banding in the late Cretace and Novacek (1976). Study of the Agua ous P aleocene and Eocene rocks in Big Fria region (Fig. 1, no. 13) by Wilson and Bend National P ark. Some P aleocene fos othe rs is unde r way. sil wood from the Black Peaks Formation The Vieja Group Uintan and Chadron shows seasonal rings and some does not ian fossils occur in vo lcaniclastic rocks, (M.L. Abbott, 1974, pers. comm.). Ripa ri and local volcanism was a major feature of an forests would not have suffered in dry the region. Tempe ratures were warm periods as interfluvial ones would have. enough to make possible the presence of Lawson (1972, p. 71) studied a polle n fl ora crocodiles in some braided streams; how· of 37 species from one locality in B ig Be nd ever, the y we re not a bundant (Wilson, National Park, which he conside red most 1977). Harris (1967) and Wilson (1977) noted No.3 Terrestrial Early Tertiary 85 the presence of caliche in Chadronian THE SOUTHEAST (early Oligocene) beds at Ash Spring and postulated a gradual drying trend for the The southeast, here defmed as beginning Eocene and Oligocene Vieja Group as a in eastern Texas, is considered as a unit whole. (Fig. 7). Accidental discovery has played a A single mammal mandible, which has major role in early Te rti ary vertebrate been recovered from the mid-Eocene Cook fmds in southeaste rn North America; there Mountain Formation at Lake Casa Blanca fore, terrestnal vertebrate finds and ter in Laredo, Webb County, Texas (Fig. 1, restnal environmental studies are rare at no. 15), is under study by John A. Wilson. the moment. The only Paleocene terrestn He identifies it as belonging to Leptoreodon al vertebrate find known from the south cf. marshi (Wilson, 1978, pers. comm.). east is the facial and palatal part of a small The prominent color banding seen m the skull, on the basis of which Simpson (1 932) early Tertiary deposits of New Mexico and named Anisonchus fortunatus. The speci Big Bend National Park, Texas, is not men was recovered from a well core in widespread in Wyoming until the early Eo Caddo Parish, Louisiana (Fig. I, no. 16) cene. Climatic change is likely to have from an approxunate depth of 750 m (Simp played a major role in triggering changes son, 1932J. Few Eocene mammals have from drab to red banded beds. Red color been reported from the southeast m the and carbonate nodules of the Willwood literature. One of these is a titanothere Formation are a good example . Neasham from the Lisbon Formation of Clark and Vondra (1972) and Bown (1977) attrib County, Mississippi !Fig. I, no. 17; Gazin uted the red banding of fl uvial overbank and Sullivan, 1942>. These authors named facies of the mid-basin region to fluctuation Notiotitanops mississippiensis on the basis of the water table. Red layers are de of this specimen. One molar of the tillodont scribed as produced in interfluvial areas Anchippus. possibly Bridgerian, was re where sedimentation rates were low in a covered from the Shark River marine warm, humid climate with periodic dry marl of New Jersey (Gazin, 1953). A smgle seasons (Neasham and Vondra, 1972, p. miacid tooth has been recovered from the 2178-2179). Red banding is also prominent base of the Gosport Sand, which overhes in the Indian Meadows Formation (proba the Lisbon Formation at the Little Stave bly Wasatchian) and in some Eoce ne rocks Creek site in Clark County, Alabama !Fig. of the Green River Basin (Picard and High, 1, no. 18; J. Thurmond, 1977, pers. comm. l. 1968). On the other hand, Braunagel and A fauna of marine and terrestrial animals Stanley (1977) described Eocene variegated has been recovered from upper Eocene redbeds in the Cathedral Bluffs Tongue of estuarine sediments of the Twiggs Clay m the Wasatch Formation in Wyoming that Georgia !Fig. I, no. 19). The snake fauna were controlled mainly by local deposition indicates semitropical or tropical conditions al events, rather than post-depositional (Holman. 1977). A terrestrial mammal conditions. According to Braunagel and fauna from this site is under study by M. Stanley (1977), upward-fining couplets of Voorhies !Voorhies, 1978, pers. comm.J. green iron-poor siltstone overlain by red Palynological data on the paleoclimate claystone represent individual floods on an of the Paleocene and Eocene of the Gulf alluvial plain near a lake. According to Coaot mdicates the presence of temperate Dorr and Gingerich (1978, pers. comm.) as weil as subtropical elements (Gray, 1960; the boundary between drab beds and var Jonps, !961; Elsik, 1965; Nichols and Tra iegated redbeds in the Chappo Member of verse, 1969: Fredericksen, 19731. The pos the Wasatch Formation is sharply time 'ibilitv exist' that the Eocene temperate transgressive in the Fossil Basin of Wyom elcm~pt, arc really part of upland floras. ing. Redbeds first appear in the middle perhaps fr'JT'I s far away a' the Appalach Tiffanian in the Fossil Basin; in the Hoback ians, admixec with coastal plam floras and Bighorn Basins they first appear in (Nich0ls and Traverse, 19691. Graham !1972 1 consider.ed temperate plant commu· the Clarkforkian (Dorr, 1978, pers. comm.). When color banding is water-table-con nities of thL easterP escarpment of ~he troll ed both local basinal conditions and Mexican IJiateau, some members ?f ~hich are prt:scnt m the Ec<·t ne of the MissiSSippi climate will be important in determining Embayment, '0 hclvt "H.. Ned progressively the color of overbank mudstones. Tulane Studies in Geology and Paleontology Vol. 15
PALEOCENE-EOCENE OUTCROP
Figure 7. Paleocene and Eocene rocks of the southeast. southward to reach Mexico in the Mio trend seen on the southern coastal plain cene. The work of Dilcher (1973) on less supports the idea that the warmth and at readily transportable plant megafossils least seasonal dryness reflected in soil from the middle Eocene of Kentucky and forming processes in the Eocene of north Tennessee indicates that some of the tem ern intermontane basins, such as those in perate e lements were part of the coastal Wyoming, was due in part to mid-conti plain flora. Foliar physiognomy of floras nent-wide climatic changes. from clay pits dug in Eocene abandoned Less is known of early Tertiary paleo channel deposits, including leaf margin pedology for the southeast than is known and leaf size analysis, indicates a tempera for the southwest. In a discussion of the ture regime of equable warm-temperate to origin of bauxite, Harder (1949) described cool-subtropical, and a moisture regime of scattered bauxite deposits of Paleocene seasonably dry to slightly moist (Dilcher, and Eoce ne age, which occur in a belt 1973). Dilcher (1973) also reported wood along the east side of the Mississippi Em with growth rings indicating seasonal fluct bayment from southwestern Georgia to uations. Wolfe (1978), also working on foli central Arkansas, and concluded that a ar physiognomy, postulated a cooling trend warm, humid climate with alternating wet from early Paleocene Tropical Rain Forest and dry seasons favored the formation of conditions in north Louisiana to late Paleo such bauxites. cene Paratropical Rain Forest conditions, Hope for future fmds of southeastern followed by an early Eocene warming mammals is greatly increased by the pros trend in the Mississippi Embayment. The pect of lignite mining in the Paleocene and middle Eocene floras studied by Dilcher Eocene rocks exposed along the west side ( 1973) are considered to be dry subtropical of the Mississippi Embayment. Strip mining by Wolfe (1978). These floras indicate a will produce extensive outcrops where soil pronounced drying trend from Paleocene cover had previously prevented paleonto to middle Eocene in the Mississippi Em logical work. Tens of thousands of acres bayment (Wolfe, 1978). This Eocene drying are a lready leased preparatory to mining :-.J o. :J Terrestrial Early Terti(lry
POLAR ST EREOGRAPHIC P ROJECTION LATE M AESTRICH! AN. 66 Ma
PACIFIC
3o • N
OCEAN
! I !LAND D SHAllOW SEA
MODIFIED FR OM VAN VALEN AND SLOAN, 1977
F igure 8. Late Cretaceous distribution of land and sec for the northern hemisphere in e ast Texas, Louisia na and Arkansas. mil formations Each contains fluvial, T he pace and scale of this mining is like ly deltaic and lignite depo"ls !Murray, I94H, to surpass anything seen up to the present p. 881341. time in east T e xas. A test mine started in the spring of 1978 excavate d Eocene lignite DISCTJSSION in Red Rive r P arish, Louisiana. There is a possibility of recove ring P a le ocene as well Recognition of e; rly Tert1ary gt·ograpl11c as Eoce n e m amma ls from Louisiana. Mur feature.c;; (F1g:. 81 and faunal and lloral m1 ray (1948) named three P a leocene forma gration patterns make possibll· sornt> prt' tions cropping out in northwest Louisiana dictions regard;rg tl1l future paleor1 tolo),.!ll' the Na b orton , Logansport and Hall Sum and paleoecolo[fiC rv1P of the tl'rrt ..,trial Tulane Studies in Geology and Paleontology Vol. 15
early Tertiary deposits of the Gulf Coast. pers. comm .). Eventually the e ffect of Increased exposure of Gulf Coast early highlands versus the effect of a seaway Tertiary sediments by strip mining may may be analysed when mammal faunas of provide opportunity to test these predic the southeast are recovered. The lack of tions in the near future. local highlands along the Gulf Coast should Clues to the affmities of southeast faunas allow a much freer interchange of animals can be provided by paleoclimatic data. more like the situation noted by Wilson The Tiffanian faunas of the Big Bend (1956) for the Miocene of the Gulf Coast region of Texas show far less similarity to than that seen in the intermontane basins. French Paleocene assemblages than the It is likely that the southeast of North high degree of similarity of the Wasatchian America belonged to a faunal province faunas of the northern intermontane basins distinct from the better-known deposits of to the Wasatchian of Europe would lead western North America in the Paleocene. one to expect. If continental drift is con It can be anticipated that Paleocene faunas sidered to have disrupted the North Amer east of central Texas would have strong ican-Europe migration route in the middle European affmities and that the faunas Eocene (Dawson et al. , 1976), this route from the late Eocene east of central Texas should be expected to have been useable would show stronger affmities to those of in the Paleocene and early Eocene. Evi the classic western North American faunas dence exists, however, for climate and of the intermontane basins than to Euro vegetational shifts, particularly a north pean assemblages. A long route across ward shift of the subtropics in the earliest northern areas with distinctly different cli Eocene, which would make high latitude mate, or a long passage including a sea intercontinental routes particularly attrac way barrier, separated the southwestern tice in the early Eocene (Sloan, 1969; P aleocene faunas such as those from Big Hickey, 1977; Wolfe, 1978). The early Eo Bend National Park, Texas, from those of cene similarities suggest that mere dis Europe. In fl uxes of animals into northern tance, for example, between Wyoming intermontane basins such as those in Wy and Europe, was not a major barrier. An oming have been interpreted as north interior seaway linked with the Gulf of ward shifts of populations originating in Mexico in roughly the same position as the subtropical or tropical e nvironments Cretaceous interior seaway existed in the (Sloan, 1969). The North American south early TiJTanian (McGrew, 1963; Sloan, 1969; east is often ignored as a possible source Fox and Olsson, 1969, Van Valen and of immigrants and a region in which new Sloan, 1977). Lilligraven (1969) considered fo rms may have been developing, although the Cretaceous seaway an important factor Wood (1977) considered it the most li kely affecting marsupial and eutherian distribu area of origin for the Rodentia. The south tion. Krause and Baird (1 979) discussed east, as well as Me xico or even Central very fragmentary mammal specimens Ame rica, must be conside re d as a source from east Texas and New J ersey, which region for immigrants. establish the presence of therian and non Other generalizations about the signifi therian mammals in North America, east cance of southern faunas yet to be found of the seaway in the Late Cretaceous. The can be made. Southern regions can be ex Paleocene seaway would have had major pected to have had overall more stable en e ffects on climate and base level as well as vironmental conditions and, therefore, a geographic effects as a barrier. These greater faunal diversity and a highe r num effects may have lingered after its with drawal. be r of animal specia lists then northern regions. Both marine and terrestrial faunas The isolating effects of highlands are show this trend (Bretsky and Lorenz, 1970; probably partially responsible for ende J . W. Wilson, 1974). Some biostratigraphic mism in California in the Paleocene (Me zones, useful in th e north, will not be recog Kenna, 1960) and Eocene (Go lz, 1976), and ni zable in the south. Differing characteriza m west Texas (Schiebout, 1974), which lions for northe rn and southe rn areas will may have been affected by a Tiffanian be required for some Paleocene zones. For shift of the continental divide (Sloan, 1977, example, a zonation defined on pantodonts No.3 Terrestrial Early Tertwry 89 the most common large herbivore in the above the floodplam surface than if mter west Texas Paleocene (Schiebout 1974) fluvtal areas are well-drained. Hetght of or periptychids would prove mor~ usefui the water table would also have consider in Texas and probably also in areas further able affect on flora and fauna. The time south, than one based on primates such necessary to form pedological features as the elegant zonations produced b~ Gin such as nodule layers also provides a clue gerich (1976) and Rose (1977) from work in to detatls of rates of deposition. Wyoming. Soil forming processes produce diagenic Paleopedological data in the early Terti alterations that are useful to the terrestrial ary of North America does reflect large early Tertiary paleoecologist in under scale climatic shifts such as the northward standing the conditions under which de shift of subtropical climate at the beginning posits formed. Calcareous nodules form of the Eocene. Changes in the water table, today in the B horizon of pedocal soils in whtch produce the striking color banding regions where rainfall is sufficient to re of red, gray and black in many fluvial de move calcium from the A horizon by leach posits, may indicate widespread climatic ing, but not enough to wash carbonates changes or smaller shifts of greater than out of the soil zones. Temperature deter seasonal duration. Soil-formed features mines the effectiveness of rainfall, because such as thick color bands are often more tt controls evaporation (Pierce and Peter widespread than any fluvial facies and son, 1975). Nodular layers appear to form usually, being water-table-controlled, they in the part of the soil where the water represent synchronous surfaces that had table fluctuates because of seasonal aridity. little original relief. Color bands have long Red layers found in banded overbank de been used informally as stratigraphic posits require an envirorunent in which in markers. For example, prominent black herited iron oxide or iron oxide-bearing beds were useful in tying together locali minerals are altered further by oxidation ties in the west Texas Paleocene (Schie (VanHouten, 1973). Nodules may occur in bout, 1970). If local effects, caused by gray sediments, as in the California coastal changes in the positioning of major chan Eocene, or in both red and gray beds, nels and accompanying changes in sedi which are in intimate association as seen ment supply, can be separated from the in the west Texas Paleocene. In the west effects of climatic patterns, a powerful Texas Paleocene beds the nodules and stratigraphic tool would result, allowing nodular layers are best developed in the correlation beyond single outcrop areas. reddest beds, suggesting that intensifica Soils have begun to be used as strati tion of one or several of the nodule-pro graphic markers as well as climate indica· ducing factors triggers the production of tors. For example, Ortlam (1971), workmg red coloration. The Eocene Sespe Forma in the Triassic and Permtan of Germany, traced red-violet layers to produce corre tion of inland California contains variegated beds in contrast to the slightly younger lations useful over all of southern Ger many. Buurman (1975) has collected data coastal formations, so the controlling factor on a vanety of uses being made of paleo may be the lower temperature and/or the higher rainfall near the coast. Small cli pedology matic changes through time may be re Accurate notation of mudstone color and sponsible. Peterson and Abbott (1975) the presence and type of nodules by work postulated a cooler depositional tempera ers in the early Tertiary continental depos· ture for coastal Eocene beds of California its can produce a great deal of mformallon than for the underlying red sediments. valuable to the paleoecologist, phylogenet Changes in the level and stability of the icist, and stratigrapher. Vertebrate pale water table, which appear responsible for ontologists should be sure to record such the color banding, indicate considerable data for their locahlles and stratigraphtc variability with time in the floodplain en sections. Workers in the terrestrial Paleo vironment. Identical overbank deposits cene and Eocene should become as alert assume a very different appearance if the to paleopedolo[!ical features as workers m post-depositional water tables lie at or the terrestoial Pleistocene are !10 Tulane Studies in Geology and Paleontology Vol. 15
ACKNOWLEDGMENTS BLACK, C. C., and M. R. DAWSON, 1966, A review of late Eocene mammalian faunas Facilities at the University of Texas, from North America: Amer. Jour. Sci., v. 264, Louisiana State University, and San Diego p. 321-349. State Umversity have been used in my re BLACK, C. C., and J . J. STEPHENS Ill, 1973, search on the southern early Tertiary. My Rodent from the Paleogene of Guanajualo, work in New Mexico has been supported Mexico: Occasional Papers, The Museum, by funds from the New Mexico Bureau of Texas Tech. Univ., v. 14, p. 1-10. Mines and Mineral Resources, the Society BOWN, T. M. , 1975, Paleocene and lower Eo of the Sigma Xi, and Bureau of Land cene r·ocks in the Sand Creek - No Water Management Grant YA-512-CT7-50. Work Creek Area, Washakie County, Wyoming: Twenty-seventh Ann. F ield Conference, Wy m Texas has been supported by the Uni oming Geol. Assoc. Guidebook, p. 55-61. versity of Texas Geology Foundation, by BOWN, T. M. , 1977, Geology and mammalian Geological Society of America Research paleontology of the Sand Creek facies, lower Grant no. 1357-70, and by the Louisiana Willwood Formation (early Eocene), Washakie State University Department of Geology. Co., Wyoming: Univ. Wyoming Ph.D. disser A Summer Faculty Research Grant from tation, unpubl., 567 p. LSU for 1977 supported work in Texas BRAUNAGEL, L. H. and K. 0. STANLEY, and New Mexico. Work in Big Bend Na 1977, Origin of variegated redbeds in the tiOnal Park was conducted under Antiqui Cathedral Bluffs Tongue of the Wasatch For lies Act permits issued to the Texas Me mation (Eocene), Wyoming: Jour. Sed. P et., v. 47, p. 1201-1219. morial Museum (1968-1972) and to the Lou BRETSKY, P. W. and D. M. LORENZ, 1970, isiana State University Museum of Geosci Adaptive response to environmental stability, ence (1976-1978). a unifying concept in paleoecology: Geol. I wish to thank John A. Wilson who al Soc. Amer., Bull., v. 81, p. 2449-2456. ways emphasized the importance of depo BUURMAN, P., 1975, Possibil ities of palaeo sitional environments to a vertebrate pale pedology: Sedimentology, v. 22, p. 289-298. ontologist and Malcolm C. McKenna who DAWSON, M. R., R. M. WEST, W. LANGS first alerted me to the uses of paleopedol TON, JR. and J.H. HUTCHISON, 1976, Pa ogy when I was a graduate student. John eogene terrestrial vertebrates; northernmost A. Wilson and Earle F. McBride of the occurrence, Ellesmere I sland, Canada: Sci ence, v. 192, p. 781 -782. Umversity of Texas at Austin, Margaret S. DILCHER, P. L., 1973, A paleoclimatic inter and James B. Stevens of Lamar Universi pretation of the Eocene floras of southeastern ty, Robert E. Sloan of the University of North America in GRAHAM, A. (ed.), Vege· Minnesota, and Richard H. Kesel of Lou tation and vegetational history of northern Isiana Slate University read lhe manuscript Latin America. Elsevier, Amsterdam, p. 39-59. and provided helpful suggestions. Bruce ELS!K, W. C. , t965, Palynology of the lower J. MacFadden of the University of Florida, Eocene Rockdale Formation, Wilcox Group. Philip D. Gingerich and John A. Dorr of Milam and Robertson Counties, Texas: Texa: the University of Michigan, and Thompson A&M Univ. Ph.D. dissertation, unpubl.. 25:l M. Stout of the University of Nebraska p. ESTES, RICHARD, 1976, Middle Paleocene brought to my allention work which I lower vertebrates from the Tongue River would otherwise overlooked. I am very Formation, southeastern Montana: Jour. P a· grateful to the colleagues mentioned leontology, v. 50, p. 500-520. above and all others who have helped me FERRUSQUIA-VILLAFRANCA, JSMAEL. in gathering data. I remain responsible for 1978, Distribution of Cenozoic vertebratl errors and oversights in this paper. faunas in middle A mer·ica and problems ol migration between North and South Americu: LITERATURE CITED I nst. Geologia, Univ. Nat!. Auton. Mexico. Bol. 101, p. 197-329. ABBOTT, P. L., J. A. MINCH, and G. L. FORSTEN, A., 197ta, Early Te •·tiary verte PETERSON, 1976, Pre-Eocene paleosol south brate faunas, Vieja Group, Trans-Peco: of Tijuana, Baja California. Mexico: Jour. Texas. Equidae; Part 1. Epihippus from tht Sed. Pel., v. 46, p. 355-36!. Vieja Group, Trans-Pecos T exas: Pearcl· BERGGREN. W. A .. M. C. McKENNA J Sellards Ser. no. 18, Texas Mem. Mus. , p. 1-5 HARDENBOL, and JOHN D. OBRADO: FORSTEN, A. , 197J b, Eady Tertiary ve•~ebrat. VICH, 1978, Revised Paleogene polarity time faunas, Vieja Group, Trans-Pecos T exaL scale: Jour. Geology, v. 86, p. 67-8!. Equidae: Part 3, Comparison of populatior1 No. :l !II
of Mesohippus from Trans-Pecos Texa:-- and hotany of fll' Goltkn \'alh.·y Formalum tt.•arlv the Big Badlands, South Dakota: Pt.•arct-· T('HJary) of Wt.>Sll'nl ~orth Dakota: Gt·ol So(.: Sellar·d s Ser. no. 18. Texas Mem. Mus , p. 12- Anwr., :\1l'rn L"lO, u~:J p. 15. HOL~1A:\. J. A. 19/i, lippt•r f:on·rw snakt•s FOX, S. K ., JR., and R. K. OLSSON, 1969, Rt.·ptiha. S(.·rpt.·ntt•SJ from Gt•or~la Jour Danian planktonic foraminifera from the Can Ht•rpf'tology. v. II, no. '2. p. 1~1-1-l;'l nonball Formation in North Dakota Jour JO:\ES. E. L.. I~Wil. En\'lronmt.·ntal tgrulic.lll('t' Paleontology, v. 43, p. 1397-1403. of palynomorphs from lov.. pr f:on·m· ~t·dt FRAKES, L. A., and E. M. KEMP, 1972, 1nnu mt•nts of Arkansas. &·tt'llt't'. ,. 13~. p I:11~i ence of continental positions on early Terti KRAUSE, D.W., .md DO="ALD BAIHD, 1!17!1, ary climates : Nature, v. 240, p. 97-100. LntP Crt•l
Vieja Group, Trans-Pecos Texas: Pearce T e xas. Inse cti vora: P earce-Se llards Se r. no. St·llards Scr no. 18, Texas Mem. Mus., p. 6- 12, T exas Mem . Mus., 18 p. 11. ORTLAM, DIETER, 1971 , Paleosols and the ir McKENNA, M. C., 1960, A continental P aleo significance in stratigra phy a nd a pplied geo n•ne vertebrate fauna from California: Amer. ology in the P e rmian and Triassic of southe rn Mus. Nov1t., no. 2024, 20 p. Ge rmany in YAALON, D. H. (ed.) , Pa leo McKENNA. M. C., 1960, Fossil Mammalia from ped ology; origin, nature, and dating of pa leo the Early Wasatchian Four Mile Fa~na, E~ sols. lsr. Univ. Press, Jerusalem , p. 32 1-327. cene of Northwestern Colorado: Umv. Cah PETERSON, G. L. and P . L. ABBOTT, 1975, forma Pubis. Geol. Sci., v. 37, p. 1-130. P a leocene age of la te ritic paleosol , weste rn McKENNA, M. C., 1962, Coll ecting small fossils San Diego County, Ca lifornia in ROSS, A. by washmg and screening: Curator, v. 5, p. and R. J . DOWLEN (eds.), Studies on the 22 1-235. Geology of Ca mp P endleton, and weste rn McKENNA, M. C., 1972a, Was Europe con San Diego County Ca lifornia: San Di ego nected d1 rectly to North America prior to the Assoc. Geologists Fie ld Trip Guidebook, 90 p. m1ddle Eocene in DOBZHANSKY, T., M. K. PICARD, M. D., a nd L. R. HIGH, 1968, Sedi HECHT, and W. C. STEEVE (eds.): Evol. me ntological cycles in the Green River For BIOI., v. 6, p. 179-188. mation (Eocene) Uinta Basin , Utah: Jour. McK ENNA, M. C., 1972b, Eocene final separa Sed. P e t. , v. 38, p. 378-383. tion of the Eurasian and Greenland-North P IE RCE, S. E. a nd G. L. PETERSON, 1975 , American land mass: 24th Int. Geol. Con g. , P a leoclimatic implications of ca liche in the Section 7, p. 275-281. non-mar ine Friars a nd Mission Valley For McKENNA, M. C., 1972c, Vertebrate paleon mations, southwestern Ca lifornia in ROSS, tology of the Togwotee Pass a rea, northwest A. and R. J . DOWLEN (eds.), Studies on the ern Wyoming in WEST , R. M. , Coordinator: Geology of Camp P endleton and weste rn San Gu1d e book-Field Conference on Tertia1·y Bio Di ego Coun ty, Ca lifornia : Sa n Diego Assoc. stratigra phy of southe rn a nd weste rn Wyom Geologists F ield Trip Guidebook, p. 71 -76. ing, Aug. 5-10, 1972
SCHIEBOUT, J . A., 1978, An overv1ew of early Wo1 hK· tmpuc.H or-s n H. ~1 WEST ~t·d Tertiary ter-restrial paleogeography of tht..• Palt•l nt: logy .:tnd P1;:th.· Tt.·<·tonws ~1 Jiw.u 1 kt·t: North American southv.'e st and Gulf Coust PuhLc ~11 t.•um Spt•t· Publ. HKL Gt·ol. no (absl. ): Gulf Coast Assoc. Geol. Soc., T rans., 2, p. 7i93. v. 28, p. 459. \\'Il.... ~O:'-:. J A 1!1:H;, \ltot.'t'lll' formotii!HlS otlld SCHUMM, S. A., 1968, Speculations conc(.•rn \'ertt•hratt• hto:-strattgrapluc ttntts, Tt•X,l') ing paleohydrologic controls of te rrestnal JClSlctl plam Anwr .\<;soc Pt·tr-,) Gt"
November 9, 1979 Tulaue Sruclies bt Geology and Paleontology Vol. 15
IConunued from p. 74 > l!J2i Tht· Veneridae of eastern America, Cenozoic and R ecent: Paleont. Amer., vol. 1, no. 5, p 209-522, pis. 32-76. )Text published Ma rch, 1927; plates, February, 1929.) l!I~H. ,\ "''" fauna from the Cook Mountain Eocene near Smithville, Bastrop County, Tl•xas. Jour. Paleonl., val. 2, p. 20-31, pis. 6-7. l!J:lfi. Tunothy Abbott Conrad . . by llarry E. Wheeler. Bull. Ame r . Paleonl. , val. 23, no. 77· Rev1ew in Bull. A.A.P.G., val. 20, p. 321-322. I!J:;;,. ~larqUis de Gregono's Cla1borne types: Nautilus, val. 50, p. 100. 1!1:!1;. Unpublished poem by T .A. Conrad: Science, val. 84, no. 2167, p. 40. 1!J:lfi. Conrad. the reticent: a ture Magazine, val. 28, p. 273-274. 1!1:;7 ThL· Claiborn1an Scaphopoda, Gastropoda and Dibranchiate Cephalopoda of the soutlwrn Umted States: Bull. Amer. Paleont. , vol. 7, no. 32, 730 p., 90 p is. I!J:lx. :'\omenclatural notes on Eocene Mollusca: Bull. Amer. Pa leont., val. 24 , no. 81 , 7 p. t!J:lx Nl' I!JI:! :'\ot~o.·s on tlw nanw Luiopa melanoswma and distribution of the species: Naulilus. ,·ol. ;,;;, p. l~X l:lO. l!lll :'-:ott" on EO<.'t'IH.' Gastropods. chiefly Ch.ubornian: Bull. Amer. P aleont., vol. 2H. no. 112. 2fi p , 2 pis. 1!111 LiliopamelaHm.;wma Hang. a correction ofdistribuuon: Nautilus, vol. 58, p. 70-71 1~11:> ,\lollu.r...t·<•n types Ill tht• Carpt'lltt•r Collt•ctum 111 the Redpath Museum: Nautdu· \'ol. ;)H. p. ~17 10~. I!IJ:) ,\I.~rqlll:-. dt• G rt•gon<)s Claiborne types: Nautilus, vol. 59, p . 34·35. 1!11.-,. Fo:-.!-!1 lrt'sh \\·att'r l\Iollusca from the State of Monagas: Bull. Ame1. Paleont., vol. :H. no. II H. :{.t p .. 2 pis. l!Hfi. The :\lollusca of tht• J ackson Eocene ol the l\lls~J~S!ppi Embayment (Sabine Rl\.l'l to Alabama 1{1\'l'rl: Bull. Aml'l'. Paleont.. vol. 30, no. 11 7, Pt. II , p. 207-563. pi• ~f).fi.->. l~llli Sulu•,·mya, nt'\' ll