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We present new fossil records of the geoemydid turtle Bridgeremys pusilla from the Uinta Formation of Utah. Turtles are abundant throughout the unit, and known taxa are similar to those from the older strata in the Upper Green River Basin in Wyoming from the Bridger and Washakie Formations. B. pusilla is known from Bridgerian deposits but was not previously known from after the Turtle Bluff Member of the Bridger Formation. The taxon was coveal with two species of the geoemydid Echmatemys (E. callopyge and E. wyomingensis), a common genus of extinct pond turtles known primarily from lacustrine and fluvial deposits in western North America, including the Uinta Basin. In addition to previously documented morphological differences, our geometric morphometric analyses revealed significant differences in epiplastral morphology between B. pusilla and the two coeval Echmatemys species. Bridgeremys pusilla shared several morphological characters with Testudinidae. However, our anatomical network analysis suggests that the carapace of B. pusilla distributed stress forces in a manner more similar to emydids (basal and derived) than to derived testudinoids (Testudinidae and Emydidae), including Echmatemys species. This finding changes our understanding of the ecology of the species and sheds light onto how geoemydid turtles of the Uinta Formation may have partitioned the available ecospace. These new Uintan records extend the geographic range of B. pusilla into the Uinta Basin and stratigraphically through the top of the Uinta Formation, extending the temporal range of the taxon by more than 4 million years through the Uintan North American Land Mammal Age to the base of the Duchesne River Formation.

BackgroundAnosteira pulchrais one of two species of the obligately-aquatic freshwater clade Carettochelyidae (pig-nosed turtles) from the Eocene of North America.Anosteira pulchrais typically rare in collections, and their distribution is poorly documented. The Uinta Formation [Fm.] contains a diverse assemblage of turtles from the Uintan North American Land Mammal Age. Whereas turtles are abundantly preserved in the Uinta Fm.,A. pulchrahas been reported only from a few specimens in the Uinta C Member.MethodsWe describe new records ofAnosteira pulchrafrom the Uinta Basin and analyze the distribution of 95 specimens from multiple repositories in the previously published stratigraphic framework of the middle and upper Uinta Fm.ResultsHere we report the first records of the species from the Uinta B interval, document it from multiple levels within the stratigraphic section and examine its uncommon appearance in only approximately 5% of localities where turtles have been systematically collected. This study details and extends the range ofA. pulchrain the Uinta Fm. and demonstrates the presence of the taxon in significantly lower stratigraphic layers. These newly described fossils include previously unknown elements and associated trace fossils, with new anatomical information presented. This study provides insight into the taxonomy ofAnosteiraspp. in the middle Eocene, and suggests the presence of a single species, though no synonymy is defined here due to limits in Bridger material.

Author(s): Smith, Heather F.; Jager, Daniel; Hutchison, J. Howard; Adrian, Brent; Townsend, K.E. Beth | Abstract: Numerous geoemydid turtle fossils from the extinct genus Echmatemys have been recovered from the middle Eocene Uinta Formation, Uinta Basin, Utah over the past several decades. Here, we tested whether co-occurring Uintan species Echmatemys callopyge and E. uintensis can be reliably differentiated based on epiplastral morphology, and whether their geospatial distributions overlapped significantly. The geographic spatial and stratigraphic distributions of Uinta Basin E. callopyge and E. uintensis specimens were compared using ArcGIS and analysis of variance (ANOVA). The analysis revealed overlapping geographic distributions of these two species, and no significant differences in stratigraphic dispersal. This finding of extensive geospatial overlap between the two Uintan Echmatemys species highlights the need for accurate taxonomic identification, such as the gular scale morphology validated here. In addition, we sought to address a methodological question regarding the relative efficacy of data complexity in this context. Using epiplastra from three additional Eocene species of Echmatemys, we employed hierarchical analyses of increasing data complexity, from standard linear dimensions to 2D geometric morphometrics to 3D laser scans, to determine the degree to which data complexity contributes to taxonomic assessments within this genus. Uintan species E. callopyge and E. uintensis were found to differ significantly in epiplastral shape as captured by all three categories of data. These findings verify that these two co-occurring species can be differentiated consistently using the shape of the gular scale, and that the use of geometric morphometrics can improve identification of fragmentary specimens. Among the non-Uintan species, dorsal and ventral 2D landmark data reliably differentiated among species, but the linear dimensions were less useful.

The most complete known North American enantiornithine was collected in 1992 but never formally described. The so-called “Kaiparowits avisaurid” remains one of the most exceptional Late Cretaceous enantiornithine fossils. We recognize this specimen as a new taxon, Mirarce eatoni (gen. et sp. nov.), and provide a complete anatomical description. We maintain that the specimen is referable to the Avisauridae, a clade previously only known in North America from isolated tarsometatarsi. Information from this specimen helps to clarify evolutionary trends within the Enantiornithes. Its large body size supports previously observed trends toward larger body mass in the Late Cretaceous. However, trends toward increased fusion of compound elements across the clade as a whole are weak compared to the Ornithuromorpha. The new specimen reveals for the first time the presence of remige papillae in the enantiornithines, indicating this feature was evolved in parallel to dromaeosaurids and derived ornithuromorphs. Although morphology of the pygostyle and (to a lesser degree) the coracoid and manus appear to remain fairly static during the 65 million years plus of enantiornithine evolution, by the end of the Mesozoic at least some enantiornithine birds had evolved several features convergent with the Neornithes including a deeply keeled sternum, a narrow furcula with a short hypocleidium, and ulnar quill knobs—all features that indicate refinement of the flight apparatus and increased aerial abilities. We conduct the first cladistic analysis to include all purported avisuarid enantiornithines, recovering an Avisauridae consisting of a dichotomy between North and South American taxa. Based on morphological observations and supported by cladistic analysis, we demonstrate Avisaurus to be paraphyletic and erect a new genus for “A. gloriae,” Gettyia gen. nov.

We described newly discovered baenid specimens from the Uintan North American Land Mammal Age (NALMA), in the Uinta Formation, Uinta Basin, Utah. These specimens include a partial skull and several previously undescribed postcranial elements of Baena arenosa, and numerous well-preserved shells of B. arenosa and Chisternon undatum. Baenids from the Uintan NALMA (46.5-40 Ma) are critical in that they provide valuable insight into the morphology and evolution of the diverse and speciose baenid family near the end of its extensive radiation, just prior to the disappearance of this clade from the fossil record. These Uintan specimens greatly increase the known variation in these late-surviving taxa and indicate that several characters thought to define these species should be reassessed. The partial cranium of B. arenosa, including portions of the basicranium, neurocranium, face, and lower jaw, was recently recovered from Uinta B sediments. While its morphology is consistent with known specimens of B. arenosa, we observed several distinct differences: a crescent-shaped condylus occipitalis that is concave dorsally, tuberculum basioccipitale that flare out laterally, and a distinct frontal-nasal suture. The current sample of plastral and carapacial morphology considerably expands the documented variation in the hypodigms of B. arenosa and C. undatum. Novel shell characters observed include sigmoidal extragular-humeral sulci, and small, subtriangular gular scutes. Subadult specimens reveal ontogenetic processes in both taxa, and demonstrate that diagnostic morphological differences between them were present from an early developmental age.

We describe a new shark fauna from Canada's westernmost Arctic island, Banks Island, Northwest Territories, based upon thousands of shark teeth recovered from lower–middle Eocene sediments of the Cyclic Member (Eureka Sound Formation) on northern Banks Island, Northwest Territories (∼74°N latitude). Based upon palynology, the sediments preserving the shark teeth are late early to middle Eocene in age and likely span the Early Eocene Climatic Optimum (EECO). The low-diversity faunal assemblage is dominated by the sand tiger sharks Striatolamia and Carcharias, but also includes relatively rare teeth of the carcharhinid Physogaleus (extinct relative of sharpnose and tiger sharks) and very rare teeth of the odontaspidid Odontaspis winkleri. We also report the occurrence of the ray Myliobatis. Based upon analogy with extant Carcharias taurus and Myliobatis, the presence of Carcharias and Myliobatis on northern Banks Island corroborates the relatively warm sea surface temperatures estimated by others fo...

Despite over a century of prospecting and field research, fossil vertebrates are exceedingly rare in Paleogene and Neogene rocks in northern Canada's Yukon Territory. Here, we describe the first records of probable Neogene vertebrate fossils from the territory, including tooth fragments of a rhinocerotid, a partial calcaneum of an artiodactyl, shell fragments of the pond turtle Chrysemys s.l. and tortoise Hesperotestudo, and a fragment of a palatine of Esox (pike). Although the tooth fragments cannot be identified solely by traditional paleontological means, we use tooth enamel microstructure, and primarily the presence of vertical Hunter-Schreger bands, to refer them to the Rhinocerotidae. As the only known record of the Rhinocerotidae in North America's western Arctic, the tooth fragments from the Wolf Creek site support the hypothesis that the clade dispersed between Asia and North America across Beringia. The fossils are consistent with a Miocene age for the Wolf Creek site that is inferred from radiometric dates of the Miles Canyon basalt flows in the vicinity of the fossil locality. Further, the tortoise and pond turtle fossils indicate a mild climate in the Yukon at the time, consistent with the vegetation reconstructions of others that indicate a warmer, wetter world in the Miocene than today.

We report new data on the type locality of the hadrosaurid ornithischian Adelolophus hutchisoni Gates et al., 2014 from the Campanian-aged Wahweap Formation of southern Utah, and the remainder of the vertebrate assemblage from the site. The type locality (UCMP V98173) is a previously-reported U.S. Geological Survey locality (USGS D815) and is stratigraphically low in the upper member of the Wahweap Formation. Additional taxa from the same site include acipenseriforms (sturgeon), amiiforms (bowfin), and lepisosteiforms (gar fish), baenid and trionychid turtles, and both theropod and ornithischian dinosaurs.

Author(s): Brinkman, Don; Aguillon-Martinez, Martha Carolina; Hutchison, J. Howard; Brown, Caleb | Abstract: A small smooth-shelled kinosternoid from the late Campanian Cerro del Pueblo Formation and the early Maastrichtian Canyon del Tule Formation of Coahuila, Mexico that is abundantly represented by isolated elements is described as Yelmochelys rosarioae gen. et sp. nov. A phylogenetic analysis concludes that Y. rosarioae is a representative of the stem lineage of the Kinosternidae. Inclusion of Y. rosarioae in Kinosternidae is supported by presence of a groove for the musk duct, the loss of the eleventh peripheral and twelfth marginal, reduced articulation between the plastron and carapace, and diamond-shaped vertebral scales. A basal position within Kinosternidae is indicated by the presence of distinct abdominal scales that meet at the midline and the presence of a relatively long costiform processes. The inclusion of Y. rosarioae in Kinosternidae supports the hypothesis that Kinosternidae and Dermatemydidae had diverged by the Late Campanian.

For the majority of the Early Caenozoic, a remarkable expanse of humid, mesothermal to temperate forests spread across Northern Polar regions that now contain specialized plant and animal communities adapted to life in extreme environments. Little is known on the taxonomic diversity of Arctic floras during greenhouse periods of the Caenozoic. We show for the first time that plant richness in the globally warm Early Eocene (approx. 55–52 Myr) in the Canadian High Arctic (76° N) is comparable with that approximately 3500 km further south at mid-latitudes in the US western interior (44–47° N). Arctic Eocene pollen floras are most comparable in richness with today's forests in the southeastern United States, some 5000 km further south of the Arctic. Nearly half of the Eocene, Arctic plant taxa are endemic and the richness of pollen floras implies significant patchiness to the vegetation type and clear regional richness of angiosperms. The reduced latitudinal diversity gradient in Early Eocene North American plant species demonstrates that extreme photoperiod in the Arctic did not limit taxonomic diversity of plants.

As a deep time analog for today's rapidly warming Arctic region, early Eocene (52–53 Ma) rock on Ellesmere Island in Canada's High Arctic (∼ 79°N.) preserves evidence of lush swamp forests inhabited by turtles, alligators, primates, tapirs, and hippo-like Coryphodon. Although the rich flora and fauna of the early Eocene Arctic imply warmer, wetter conditions than at present, the quantification of Eocene Arctic climate has been more elusive. By analyzing oxygen isotope ratios of biogenic phosphate from mammal, fish, and turtle fossils from a single locality on central Ellesmere Island, we infer early Eocene Arctic temperatures, including mean annual temperature (MAT) of ∼ 8 °C, mean annual range in temperature of ∼ 16.5–19 °C, warm month mean temperature of 19–20 °C, and cold month mean temperature of 0–3.5 °C. Our seasonal range in temperature is similar to the range in estimated MAT obtained using different proxies. In particular, relatively high estimates of early Eocene Arctic MAT and SST by others that are based upon the distribution of branched glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in terrestrial soil bacteria and isoprenoid tetraether lipids in marine Crenarchaeota fall close to our warm month temperature, suggesting a bias towards summer values. From a paleontologic perspective, our temperature estimates verify that alligators and tortoises, by way of nearest living relative-based climatic inference, are viable paleoclimate proxies for mild, above-freezing year-round temperatures. Although for both of these reptilian groups, past temperature tolerances probably were greater than in living descendants.

The partial carapace of a “macrobaenid” turtle from the Geoncheonri Formation (Lower Cretaceous) in Gyeongsan City near Daegu Metropolian City, South Korea, is referred to Kirgizemys Nessov and Khozsatzky, 1973. The specimen most closely resembles K. exaratus Nessov and Khozsatzky, 1973 from the Albian of Kyrgyzstan. It is the first turtle fossil described from the Mesozoic sediments on the Korean peninsula.

Gomphochelys nanus, new genus and species, is described from the earliest Wasatchian (biohorizon Wa 0; ∼55.8 Ma) of the southeastern Bighorn Basin, Washakie County, Wyoming. The new taxon represents the only known dermatemydid from the Paleocene–Eocene Thermal Maximum (PETM) interval and extends the lineage back from previous records by approximately 2 million years. Gomphochelys nanus has a thick tricarinate carapace and differs from other dermatemydids in attaining a smaller adult body size, having reduced plastral features, a posteriorly situated gular–humeral sulcus, an acarinate pygal, and thick shortened peripherals. Reexamination of previously described fossil dermatemydids suggests that the taxa Baptemys tricarinata and Kallistira costilata are junior synonyms of the middle–late Wasatchian Notomorpha garmanii, and Baptemys fluviatilis is likely a junior synonym of Baptemys wyomingensis. Gomphochelys nanus is a stem dermatemydid that is similar to N. garmanii but differs in possessing symplesiomorphies with the Late Cretaceous–Paleocene genera Agomphus and Hoplochelys. Aspects of shell morphology suggest that G. nanus was a commensurate swimmer and bottom-walker like extant Dermatemys and Staurotypus. The presence of a dermatemydid (a tropically distributed clade) in the southeastern Bighorn Basin during the PETM (when global temperatures increased by 5°C–10°C over a period of ∼60 ky) further supports the hypothesis that climate was megathermal in the region during this interval and is consistent with previously documented geographic range changes in both plants and animals. Dermatemydids disappear from the fossil record at the end of the PETM and don't reemerge until the next warming event, Eocene Thermal Maximum 2.http://zoobank.org/urn:lsid:zoobank.org:pub:19A98079-5CAD-4BC5-8C21-2810AA576D98 SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

The Late Eocene (Chadronian NALMA) Hardie Mine local fauna of the Clinchfield Formation in Wilkinson County, Georgia, preserves the most diverse turtle fauna in the Eocene of southeastern North America. This fauna includes at least five taxa including a dermochelyid, a cheloniid, a trionychid, a testudinoid, and an unidentified cryptodire. Chelonioids and trionychids are the most common turtles in this near-shore marine deposit. The aquatic testudinoids from the Hardie Mine site represent the oldest records from southeastern North America, a region that exhibits a high diversity of extant aquatic testudinoids.

(2005). A reappraisal of some Paleogene turtles from the southeastern United States. Journal of Vertebrate Paleontology: Vol. 25, No. 4, pp. 979-982.

Department of Anthropology, University of Iowa, Iowa City, IA 52242, USAThe reptile fauna of the Eocene Pondaung Formation of central My-anmar (Fig. 1) has received little attention compared to its well-knownmammalian fauna (e.g., Colbert, 1938; Tsubamoto et al., 2000). In priorreports, Buffetaut (1978) described indeterminate crocodylians and dy-rosaurids. Hutchison et al. (in press) described carettochelyid, trionychid,testudinoid, and pelomedusoid turtles from the formation. They addi-tionally noted the presence of agamid lizards, a pristichampsine croco-dilian, and snakes. The snakes are described here.The occurrence of snakes in the Pondaung Formation is significantbecause the fossil history of Paleogene South Asian snakes has histori-cally been under studied relative to the North American and Europeanrecords (e.g., Rage, 1984; Szyndlar, 1984; Holman, 2000), despite hypoth-eses predicting the region as the origin of extant clades (e.g., Underwoodand Stimson, 1990; Rage et al., 1992). The South Asian record consistsprimarily of marine palaeophiid taxa as well as terrestrial/terrigenousspecimens referred to Boidae (Boinae + Erycinae, Table 1). The onlyderived snakes from the South Asian Paleogene are six colubrid verte-brae from the late Eocene Krabi Basin of Thailand (Rage et al., 1992)and a single vertebra referred to Colubroidea (possibly Colubridae) fromthe early Eocene of India (Rage et al., 2003). The absence of coevalcolubroids elsewhere (Rage, 1988), combined with the occurrence of theKrabi Basin record, led Rage et al. (1992) to conclude that Asia repre-sents the center of origin for Colubridae, the most speciose and diverseextant snake clade.The Pondaung snake record consists of two specimens derived fromterrestrial sediments occurring in the upper 100+ meters of the otherwisemarine Pondaung Formation as it crops out to the west and northwest ofMogaung village, Myaing Township, central Myanmar (Fig. 1). Thesnake localities are interpreted as swale-fills and/or paleosols depositedin an ancient floodplain (Soe et al., 2002; see also Ciochon and Gunnell,2002, and Gunnell et al., 2002 for more detailed discussions of the lithol-ogy and stratigraphy of these localities). Traditionally, the age of thePondaung fauna was considered to be late Eocene (e.g., Pilgrim, 1928;Bender, 1983); however, Holroyd and Ciochon (1994) concluded that thePondaung fauna is latest middle Eocene (Bartonian) in age and broadlycontemporaneous with Asian faunas assigned to the SharamurunianLand Mammal Age, a finding confirmed by fission-track dates of 37.2 ±1.3 Ma (Tsubamoto et al., 2002). These findings indicate that thePondaung fauna is slightly older than the Krabi Basin record, which hasbeen dated between 33.54 and 34.65 Ma in age based on paleomagneticcorrelations (Benammi et al., 2001).Here we describe the Pondaung snakes and discuss their relativeimplications for paleoecology, divergence timings, and biogeographichistories. We refrain from erecting new taxa for the Pondaung speci-mens because the record is limited to just the two elements and neitheris complete. Additional material will be necessary to determine wheth-er or not the Pondaung record represents new, distinct taxa, or indi-vidual or intracolumnar variants of previously known South Asiansnakes.

The skull of a new turtle from the Tiffanian (Paleocene) of the Goler Formation, Kern County, California is the first confirmed baenid from the Pacific slope of North America. Goleremys mckennai, gen. et sp. n., is represented by a nearly complete skull that shares two weak apomorphies with the latest Cretaceous and Paleocene genera, Stygiochelys and Palatobaena. The new genus appears to be the sister taxon of those eubaenine genera.

The holotype of Judithemys sukhanovi gen et. sp. nov. from the Late Cretaceous (Campanian) Dinosaur Park Formation of Alberta, Canada, has been included in four cladistic analyses. New material allows for a more complete description of this taxon. Judithemys sukhanovi is represented by 65 specimens (most very fragmentary) including one virtually complete skeleton (the holotype) and several partial shells. It differs from all other “macrobaenids” in the combination of wide vertebral scales, absence of central plastral fontanelles, and lack of strongly upturned peripherals. The morphology of Judithemys reiterates a suite of characters (large size, well-differentiated neurals reduced to eight, and greater overlap of the twelfth marginal scales onto the second suprapygal) common to Late Cretaceous–Paleocene “macrobaenids” and distinct from Early Cretaceous members. Judithemys and “Clemmys” backmani are close in morphology, geography, and stratigraphic position and are possibly closely related phyloge...

The record of turtles in the Denver Basin spans four formations (Fox Hills, Laramie, Arapahoe, and Denver) that range from Late Cretaceous (Lancian) to early Paleocene (Puercan) in age. We recognize at least fifteen distinct, although fragmentary, species-level taxa, including Pleurosternidae ( Compsemys ), Baenidae ( Neurankylus, Plesiobaena, Stygiochelys , and Palatobaena ), Kinosternia ( Hoplochelys ), Adocidae ( Adocus ), Nanhsiungchelyidae ( Basilemys ), Trionychidae ( Axestemys, Aspideretoides, Helopanoplia , and another plastomenine), Macrobaenidae, and Chelydridae. Notable among these are the best-preserved skull of Compsemys , a new chelydrid genus, the most northerly confirmed record of Hoplochelys , and the most southerly records of Helopanoplia , Stygiochelys , and Macrobaenidae in the Rocky Mountain region. We also present evidence for synonymy of Paleotrionyx and Conchochelys with Axestemys , and the first cranial material assignable to Axestemys . The early Paleocene (Puercan) part of the Denver Formation yielded the most diverse assemblage, followed by the Cretaceous (Lancian) part of the Denver Formation and Laramie Formation. The Cretaceous samples are not demonstrably different from more northerly comparable faunas, but the more diverse Paleocene part of the Denver Formation exhibits a unique combination of taxa compared to contemporaneous faunas to the north and south.

Arctisorex polaris, gen.n., sp.n., from the late Neogene of Ellesmere Island, Nunavut, is the most northerly record thus far of a shrew. The genus is represented by the posterior moiety of a dentary and last two molars. The well-developed M3 and the extreme distance between the articular condyles, separated by a narrow interarticular isthmus, agrees best with the neomyine shrews. The expansion and anterior inclination of the coronoid process, extreme elongation of the third molar that results in it being longer than the M2, and the M3 with a distinct entoconid valley, are unique among soricids. We suggest that Arctisorex may be the only shrew specialized for frugivory.

BACKGROUND: Discovery of Eocene non-marine vertebrates, including crocodylians, turtles, bony fishes, and mammals in Canada's High Arctic was a critical paleontological contribution of the last century because it indicated that this region of the Arctic had been mild, temperate, and ice-free during the early - middle Eocene (∼53-50 Ma), despite being well above the Arctic Circle. To date, these discoveries have been restricted to Canada's easternmost Arctic - Ellesmere and Axel Heiberg Islands (Nunavut). Although temporally correlative strata crop out over 1,000 km west, on Canada's westernmost Arctic Island - Banks Island, Northwest Territories - they have been interpreted as predominantly marine. We document the first Eocene bony fish and crocodyliform fossils from Banks Island. PRINCIPAL FINDINGS: We describe fossils of bony fishes, including lepisosteid (Atractosteus), esocid (pike), and amiid, and a crocodyliform, from lower - middle Eocene strata of the Cyclic Member, Eureka Sound Formation within Aulavik National Park (∼76°N. paleolat.). Palynology suggests the sediments are late early to middle Eocene in age, and likely spanned the Early Eocene Climatic Optimum (EECO). CONCLUSIONS/SIGNIFICANCE: These fossils extend the geographic range of Eocene Arctic lepisosteids, esocids, amiids, and crocodyliforms west by approximately 40° of longitude or ∼1100 km. The low diversity bony fish fauna, at least at the family level, is essentially identical on Ellesmere and Banks Islands, suggesting a pan-High Arctic bony fish fauna of relatively basal groups around the margin of the Eocene Arctic Ocean. From a paleoclimatic perspective, presence of a crocodyliform, gar and amiid fishes on northern Banks provides further evidence that mild, year-round temperatures extended across the Canadian Arctic during early - middle Eocene time. Additionally, the Banks Island crocodyliform is consistent with the phylogenetic hypothesis of a Paleogene divergence time between the two extant alligatorid lineages Alligator mississippiensis and A. sinensis, and high-latitude dispersal across Beringia.

The East African Rift separates the northwestern and southeastern Ethiopian high plateaus, which are capped by massive Cenozoic volcanics overlying thick deposits of marine and nonmarine Mesozoic sediments. During geological mapping projects of the 1920s-1930s, a few Mesozoic vertebrate fossils were found on the southeastern plateau. in contrast, beginning in 1976, and then from 1993 to the present, paleontological field work in the Abay (Blue Nile) River gorge along the eastern edge of the northwestern plateau resulted in the discovery of fossil chondrichthyans (Priohybodus, Hybodus, Rhinobatos), osteichthyans (Lepidotes, cf. Pycnodus), dipnoans (Asiatoceratodus), chelonians (Pelomedusidae, Plesiochelyidae, Pleurosternidae), crocodylians (Goniopholis), dinosaurs, (cf. Acrocanthosaurus Hypsilophodontidae), pollen and other microfossils documenting a coastal biota in part, if not entirely, of latest Jurassic (Tithonian) age. These fossils include new biogeographic records for Africa and document biostratigraphic range extensions. The Ethiopian Mesozoic fauna adds to the growing evidence of limited interchange of vertebrates between Africa and Western Europe during the transition from the Jurassic into the Cretaceous.

There is a marked, possibly stepwise, extinction of marine taxa across the Cenomanian-Turonian boundary. Across the boundary in southwestern Utah, there is only minor species-level extinction of brackish-water taxa, and an actual increase in diversity of fully terrestrial organisms; significant family-level extinctions are restricted to aquatic taxa such as fishes and turtles. It is not possible in the nonmarine setting to determine if this is a gradual, stepwise, or instantaneous extinction, or to what degree it correlates to marine extinction events. Nonmarine faunas underwent no major change during the transgressive phase of the Greenhorn cycle, and the loss of aquatic taxa along with displacement (but not extinction) of brackish-water vertebrates and some marsupial mammals is first apparent in rocks deposited during regression in the Turonian. The loss of flood-plain habitat at maximum transgression may have caused the extinction of some of the aquatic taxa. The absence but not extinction of certain taxa on flood plains during the Greenhorn regression suggests that there may be some significant difference in transgressive and regressive flood plains. Drawdown increases the gradients of rivers and results in incision along coastal margins. This restricts the extent of brackish-water environments and may have had an impact on faunal compositions of riverine systems and contributed to extinction within aquatic communities. This pattern is quite different from that at the Cretaceous-Tertiary (K-T) boundary. Aquatic taxa underwent relatively minor losses at that boundary, whereas terrestrial organisms underwent major extinction. It appears that much of the Late Cretaceous aquatic community was restructured (mostly by exclusion of many taxa rather than extinction) and reduced in diversity during large-scale regression in the middle of the Maastrichtian before the end of the Cretaceous. This aquatic community was living in a rapidly expanding environment (overall regression of marine waters) at the K-T boundary. The extinction of terrestrial taxa at the boundary is unlike the pattern observed at the Cenomanian-Turonian boundary and suggests that some mechanism other than eustatic change played a significant role in the extinction.

Mammals dominate modern terrestrial herbivore ecosystems, whereas extant herbivorous reptiles are limited in diversity and body size. The evolution of reptile herbivory and its relationship to mammalian diversification is poorly understood with respect to climate and the roles of predation pressure and competition for food resources. Here, we describe a giant fossil acrodontan lizard recovered with a diverse mammal assemblage from the late middle Eocene Pondaung Formation of Myanmar, which provides a historical test of factors controlling body size in herbivorous squamates. We infer a predominately herbivorous feeding ecology for the new acrodontan based on dental anatomy, phylogenetic relationships and body size. Ranking body masses for Pondaung Formation vertebrates indicates that the lizard occupied a size niche among the larger herbivores and was larger than most carnivorous mammals. Paleotemperature estimates of Pondaung Formation environments based on the body size of the new lizard are approximately 2–5°C higher than modern. These results indicate that competitive exclusion and predation by mammals did not restrict body size evolution in these herbivorous squamates, and elevated temperatures relative to modern climates during the Paleogene greenhouse may have resulted in the evolution of gigantism through elevated poikilothermic metabolic rates and in response to increases in floral productivity.

Formal names, diagnoses, and descriptions are supplied for previously identified, but informally named, cryptodiran turtles from the Paleogene of Montana and Wyoming, USA. Two new early Paleocene (Puercan) turtles are described from Montana: a peculiar trionychid, Atoposemys entopteros gen. et. sp. nov., from the Tullock Member of the Fort Union Formation, and a chelydrid, Tullochelys montanus gen. et. sp. nov., from both the Tullock Member of the Fort Union Formation and the Hell Creek Formation. From the Wasatchian (early Eocene) Wasatch and Willwood formations of Wyoming, the following taxa are described: the earliest North American emydid, Psilosemys wyomingensis gen. et. sp. nov.; a platysternid, Cardichelyon rogerwoodi gen. et. sp. nov.; and Planetochelys dithyros sp. nov. A new family, Planetochelyidae, within the Trionychoidae, is erected for Planetochelys.

Two new genera (Derrisemys and Plastomenoides) and three new species (D. sterea, P. lamberti, P. tetanetron) of plastomenine trionychids from Montana and Wyoming are described. They are unique within the Trionychidae in having the entoplastron locked into notches in the hyoplastra and restricting midline kinesis. D. sterea occurs in the Lancian NALMA (North American Land Mammal Age) of Montana and Wyoming and Puercan NALMA of Montana. P. tetanetron occurs in the Puercan NALMA of Montana. P. lamberti occurs in the Torrejonian NALMA of Montana and Tiffanian NALMA of Wyoming and Utah. Plastomenus acupictus Hay 1907 from New Mexico is referred to Derrisemys. The age of D. acupictus is uncertain but is likely from early Paleocene (Torrejonian NALMA).

Two genera of kinosternids in the Eocene of North America exhibit specializations of the Kinosteminae such as the presence of incised musk ducts, loss of one suprapygal, and a generally derived neural pattern. The shell of Baltemys staurogastros, gen., et sp. no v., from the Wasatchian (early Eocene) of Wyoming shows striking phenetic resemblance to that of Staurotypus but these are judged as primitive features on the basis of out-group analysis. Xenochelys lostcabinensis, sp. nov., from the Wasatchian and X. bridgerensis, sp. nov., from the Bridgerian of Wyoming exhibit additional derived features of the extant kinosternines such as the reduction in musk duct length, development of an intergular scale, and expansion of the plastron. Baltemys and Xenochelys lack plastral kinesis. The morphology of the fossil forms bridges much of the morphological gap between the extant Kinosterninae and Staurotypinae. The wealth of derived morphological features that the two subfamilies share indicate that they ...

At least 33 vertebrate taxa from the lower and middle Siwalik Group (middle and late Miocene) of southern and western Nepal compare well with assemblages from the lower and middle Siwaliks of Pakis...

Turtles are among the most widespread, abundant, and diverse fossil vertebrate groups in the latest Cretaceous. On the basis of new data from the Hell Creek Formation (North Dakota) and Lance and Ferris Formations (Wyoming) and previously published data from Montana, we examined latest Cretaceous intraregional variability in this group, comparing these three areas to a large data set previously published from the Hell Creek Formation of Montana. Using discrete locality occurrences as an index of relative abundance, significant differences were found. Trionychids are the only group that evinces no differences among the four study areas. Baenids and kinosternoids are more common than expected in North Dakota. The pleurosternid Compsemys, chelydrids, and Adocus are notably rare in the Ferris Formation, and the terrestrial turtle Basilemys is more abundant there than expected. The Lance Formation differs in the greater relative abundance of uncommon taxa, i.e., chelydrids, the macrobaenid "Clemmys" backmani, kinosternoids, and Basilemys. These differences are statistically independent of simple lithologic differences and thus appear to reflect underlying heterogeneity in the aquatic habitats of the latest Cretaceous that may not have obtained to the same degree in terrestrial habitats. The idea of heterogeneous aquatic habitats is consistent with depositional models indicating that the northern Great Plains area was dominated by dynamic fluvial systems that created an unstable landscape. Adaptation to fluctuating environments was probably a feature of latest Cretaceous aquatic vertebrate ecology and may be a factor in their greater relative success in surviving Cretaceous-Tertiary boundary events.

Publisher Summary This chapter discusses specimen of Desmatochelys lowi from the Mancos Shale of northern Arizona. The turtle was completely disarticulated and based on the orientation of the skull, carapace elements might have arrived on the bottom in an upside-down position. A plesiosaur tooth found in association with the skeleton suggested a possible scavenger of the carcass and none of the bones showed any evidence of predation. The skull and anterior part of the lower jaw were recovered, together with most of the cervical vertebrae, substantial portions of the carapace, part of the plastron, one humerus, one femur, and some distal elements of the flippers. Anteriorly, the posterior margin of the external nares was formed by a pair of nasal bones that contact the frontals posteriorly and are bounded laterally by the maxilla. The frontals are large and irregularly shaped with an anterior process that meets the nasals and a lateral process that forms part of the dorsal margin of the orbits. The prefrontals are small bones that form dorsal lappets in the anterodorsal comer of the orbits and are separated from each other in the midline by the anterior processes of the frontals. Moreover, the large postorbitals separate the parietals from the squamosals and make a major contribution to the posterior margin of the skull.

THE TURTLE FAUNA FROM the Williamsburg Formation of the Paleocene of South Carolina is the most diverse yet known from the Paleocene of eastern North America, although this may reflect the mixed nature of the recovered assemblage. The assemblage is unusually rich in kinosternoid turtles, comprising approximately 60 percent of the taxa and including Adocus, Agomphus, and four other kinosternoids. The remaining taxa include one or two trionychids, two pleurodires (Taphrosphys and ?Bothremys) and three chelonioids (Osteopygis, unidentified toxochelyine and cheloniid). The fauna is notably different from coeval western interior faunas in diversity and abundance of kinosternid turtles and in the absence of baenoids, chelydroids, and testudinoids.

Paleontologic investigation of the early Tertiary Eureka Sound Formation on Ellesmere Island, N.W.T., demonstrates the presence of well developed marine beds in that unit, which was previously considered almost completely terrestrial. This new interpretation is based largely upon the occurrence of remains of foraminifers and fish at four localities.

The abundant chelonian faunas of the Hell Creek and Tullock formations of McCone and Garfield counties, Montana, span the Cretaceous/Tertiary boundary and provide a basis for assessing extinction and changes in diversity. Over three thousand specimens were counted on a modified minimum number basis from 510 localities. The Lancian (Maastrichtian) part of the Hell Creek Formation contains at least 19 genera and subgenera of turtles and probably a greater but undetermined number of species and comprises the most diverse fossil turtle fauna known from a single rock unit. At least 15 generic level taxa survive into the Puercan (early Paleocene) part of the overlying Tullock Formation and only one new genus appears. The magnitude of the change in diversity across the Cretaceous/Tertiary boundary is less than or compaable to examples within the Tertiary and is readily explained by moderate ecological changes.

The first specimen of the giant marine snake Pterosphenus Lucas is recorded from a carbonate platform environment in the Late Eocene (Jackson Age) of the Crystal River Formation of Alachua County, Florida. The great enlargement of the marrow cavities and concomitant thinning of the vertebral walls are interpreted as specializations to a completely aquatic and fully marine habitus. The Florida specimen indicates that Pterosphenus was not limited to estuarine and low salinity environments as previously proposed.

Members of the family Baenidae cease significant growth and co-ossify the shell as adults. Recognition of adults allows size to be effectively used as a means of taxon discrimination in taxonomic, stratigraphie, and ecologie studies. The feature is used to discriminate the Eocene genera Baena and Chisternon and trace their increase in size through time.

Lower vertebrates from the Early Eocene Eureka Sound Formation, Ellesmere Island, Canadian Arctic Archipelago, form a mixed aquatic—riparian—terrestrial assemblage similar to that of many North American Late Cretaceous and Paleogene continental deposits. Taxa include the bony fishes Amia and Lepisosteus, the salamander Piceoerpeton, anguid and varanid lizards and a boid snake. Turtles include two emylids, the tortoise Geochelone, and anosteirine, Trionyx s.s. and an unidentified turtle adapted for durophagy. The durophagous alligator Allognathosuchus is also present. The varanid, tortoise and alligator indicate an equable climate with winters that rarely suffered freezing temperatures. These animals (especially the varanid) have high temperature optima today. Such optima are more likely to have occurred seasonally, under present obliquity of the earth's axis, than with the low obliquity model that has been suggested by paleobotanical data. If so, these animals must have undergone periods of winter dormancy, unlike their living relatives. Zoogeographic affinities of the lower vertebrates are generally with North America although some of the taxa also occur in Palaeogene Europe; only the anosteirine turtle shows Asian affinities. Two of the taxa appear to have been endemic to the Arctic region, and the assemblages as a whole may have been part of a pan-Arctic fauna rather than resembling that of any northern continent in particular.

We present here preliminary findings of recent field studies on Miocene Lower Siwaliks deposits of southwestern Nepal. Twenty-four vertebrate taxa are now represented from over 50 localities. The fauna is largely aquatic, being dominated by fish, turtles, crocodiles and aquatic snakes. Lithologies indicate deposition in sluggish streams and associated environments. Biostratigraphy indicates correlation between the composite Nepal fauna and Lower Siwaliks faunas of India and Pakistan, a conclusion corroborated by a palaeomagnetic study showing an age of 9–10 Myr for some of the fossil sites. A hominoid specimen, found in Tinau Khola, is 9.0–9.5-Myr old. It is similar to several specimens of small Miocene hominoids from Pakistan and India, and helps fill the geographical gap between hominoids collected previously in northwestern India and southern China.

The discovery of a turtle in the Early Jurassic(185 million years before present) Kayenta Formation of northeastern Arizona provides significant evidence about the origin of modern turtles. This new taxon possesses many of the primitive features expected in the hypothetical common ancestor of pleurodires and cryptodires, the two groups of modern turtles. It is identified as the oldest known cryptodire because of the presence of a distinctive cryptodiran jaw mechanism consisting of a trochlea over the otic chamber that redirects the line of action of the adductor muscle. Aquatic habits appear to have developed very early in turtle evolution. Kayentachelys extends the known record of cryptodires back at least 45 million years and documents a very early stage in the evolution of modern turtles.