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A small lot of fossil whale barnacles from the Upper Pleistocene of California and the Middle Pleistocene (Chibanian) of Oregon (United States West Coast), described in a 1972 unpublished MA thesis, are formally described and illustrated herein. In that thesis, a new genus and species name were proposed; however, according to the International Code of Zoological Nomenclature, they have no taxonomic standing and are thus unavailable. Based on our reappraisal, two specimens in this lot belong to a new, extinct species that can be assigned to the purportedly extant genus Cetopirus. Cetopirus polysyrinx sp. nov. differs from congeners in that its secondary T-shaped flanges are multitubiferous internally, that is, they are perforated by a high number of irregularly-sized and irregularly-spaced tubules that result in a spongy aspect in transverse section. Whether or not this peculiar condition had any adaptive significance is difficult to determine. Considering that Cetopirus is currently known as an obligate epibiont of right whales (including the North Pacific form Eubalaena japonica (Lacépède 1818)), the host of C. polysyrinx sp. nov. was E. japonica or some other species of Eubalaena. The Plio-Pleistocene deposits of the Pacific coast of North America have yielded a rather idiosyncratic fossil whale barnacle fauna, inclusive of the genera Cetolepas, Cryptolepas and now Cetopirus, which seemingly contrasts with all other coeval assemblages worldwide, the latter being in turn dominated by Coronula spp.

Turtles are key components of modern vertebrate faunas and their diversity and distributions are likely to be affected by anthropogenic climate change. However, there is limited baseline data on turtle taxonomic richness through time or assessment of their past responses to global environmental change. We used the extensive Triassic–Palaeogene (252–223 Ma) fossil record of terrestrial and freshwater turtles to investigate diversity patterns, finding substantial variation in richness through time and between continents. Globally, turtle richness was low from their Triassic origin until the Late Jurassic. There is strong evidence for high richness in the earliest Cretaceous of Europe, becoming especially high following the Cretaceous Thermal Maximum and declining in all continents by the end‐Cretaceous. At the K–Pg boundary, South American richness levels changed little while North American richness increased, becoming very high during the earliest Palaeogene (Danian). Informative data are lacking elsewhere for this time period. However, the Selandian–Thanetian interval, approximately 5 myr after the K–Pg mass extinction, shows low turtle richness in Asia, Europe and South America, suggesting that the occurrence of exceptional turtle richness in the post‐extinction Paleocene fauna of North America is not globally representative. Richness decreased over the Eocene–Oligocene boundary in North America but increased to its greatest known level for Europe, implying very different responses to dramatic climatic shifts. Time series regressions suggest number of formations sampled and palaeotemperature are the primary influencers of face‐value richness counts, but additional factors not tested here may also be involved.

Past responses to environmental change provide vital baseline data for estimating the potential resilience of extant taxa to future change. Here, we investigate the latitudinal range contraction that terrestrial and freshwater turtles (Testudinata) experienced from the Late Cretaceous to the Paleogene (100.5–23.03 mya) in response to major climatic changes. We apply ecological niche modeling (ENM) to reconstruct turtle niches, using ancient and modern distribution data, paleogeographic reconstructions, and the HadCM3L climate model to quantify their range shifts in the Cretaceous and late Eocene. We then use the insights provided by these models to infer their probable ecological responses to future climate scenarios at different representative concentration pathways (RCPs 4.5 and 8.5 for 2100), which project globally increased temperatures and spreading arid biomes at lower to mid-latitudes. We show that turtle ranges are predicted to expand poleward in the Northern Hemisphere, with decreased habitat suitability at lower latitudes, inverting a trend of latitudinal range contraction that has been prevalent since the Eocene. Trionychids and freshwater turtles can more easily track their niches than Testudinidae and other terrestrial groups. However, habitat destruction and fragmentation at higher latitudes will probably reduce the capability of turtles and tortoises to cope with future climate changes. Ministerio de Ciencia e Innovación | Ref. FJC2020-044836-I European Commission | Ref. H2020, n. 947921 NERC | Ref. NE/J020389/1

International audience; The paleogeographic history of the Indian subcontinent is unique among Earth’s landmasses. From being part of the southern supercontinent Gondwana for most of the Mesozoic, through a period of isolation as a drifting entity in the Late Cretaceous, to colliding with Asia near the Paleocene-Eocene boundary, the Indian subcontinent has been associated with, and dissociated from, a variety of landmasses. This paleogeographic history has been invoked to explain aspects of the subcontinent’s modern-day fauna, with a combination of endemic radiations, remnants from Gondwana, and more recent immigrants from Laurasia. Here, network approaches document how vertebrate faunas of the Indian subcontinent, and specifically their relationships to those of other landmasses, changed during the subcontinent’s isolation from close faunal relationships with Madagascar and South America in the Late Cretaceous to a more Laurasian fauna most similar to those of Europe by the Eocene.

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.

A new bird coracoid from the Uinta Formation in the Uinta Basin in Utah (USA) records the presence of the only known pangalliform from the middle Eocene of North America, occurring in a &gt, 15 million year gap in their history. This fossil represents a new taxon, informally termed the Uintan paraortygid, which is also currently the best-supported record of the extinct Paraortygidae in North America (and among the oldest records of the group in the world). The specimen exhibits a derived enlarged procoracoid prominence with a small procoracoid process, and concave elliptical scapular cotyle that are shared with the middle Eocene paraortygids, Xorazmortyx and Scopelortyx, however, the Uintan paraortygid also has a possibly autapomorphic (pneumatic) fossa adjacent to the scapular cotyle. The similarity in body size and morphology among these widely distributed early paraortygids suggests phylogenetic affinity among them. Given their occurrence in the United States, Uzbekistan, and Namibia during the middle Eocene, these birds likely were good fliers with an increased ability to disperse, and probably had a flexible biology or diet allowing them to occupy a diversity of habitats from coasts and forests to semi-arid savannah-like habitats. The problematic early records of Odontophoridae need to be reexamined as potential members of Paraortygidae and associates of these small-bodied taxa.

Our ability to correlate biological evolution with climate change, geological evolution, and other historical patterns is essential to understanding the processes that shape biodiversity. Combining data from the fossil record with molecular phylogenetics represents an exciting synthetic approach to this challenge. The first molecular divergence dating analysis (Zuckerkandl and Pauling 1962) was based on a measure of the amino acid differences in the hemoglobin molecule, with replacement rates established (calibrated) using paleontological age estimates from textbooks (e.g., Dodson 1960). Since that time, the amount of molecular sequence data has increased dramatically, affording ever-greater opportunities to apply molecular divergence approaches to fundamental problems in evolutionary biology.

Large-scale analysis of the fossil record requires aggregation of palaeontological data from individual fossil localities. Prior to computers, these synoptic datasets were compiled by hand, a laborious undertaking that took years of effort and forced palaeontologists to make difficult choices about what types of data to tabulate. The advent of desktop computers ushered in palaeontology's first digital revolution—online literature-based databases, such as the Paleobiology Database (PBDB). However, the published literature represents only a small proportion of the palaeontological data housed in museum collections. Although this issue has long been appreciated, the magnitude, and thus potential significance, of these so-called ‘dark data’ has been difficult to determine. Here, in the early phases of a second digital revolution in palaeontology­—the digitization of museum collections—we provide an estimate of the magnitude of palaeontology's dark data. Digitization of our nine institutions' holdings of Cenozoic marine invertebrate collections from California, Oregon and Washington in the USA reveals that they represent 23 times the number of unique localities than are currently available in the PBDB. These data, and the vast quantity of similarly untapped dark data in other museum collections, will, when digitally mobilized, enhance palaeontologists’ ability to make inferences about the patterns and processes of past evolutionary and ecological changes.

Euprimates are unusual among mammals in having fingers and toes with flat nails. While it seems clear that the ancestral stock from which euprimates evolved had claw-bearing digits, the available fossil record has not yet contributed a detailed understanding of the transition from claws to nails. This study helps clarify the evolutionary history of the second pedal digit with fossils representing the distal phalanx of digit two (dpII), and has broader implications for other digits. Among extant primates, the keratinized structure on the pedal dpII widely varies in form. Extant strepsirrhines and tarsiers have narrow, distally tapering, dorsally inclined nails (termed a ‘grooming claws’ for their use in autogrooming), while extant anthropoids have more typical nails that are wider and lack distal tapering or dorsal inclination. At least two fossil primate species thought to be stem members of the Strepsirrhini appear to have had grooming claws, yet reconstructions of the ancestral euprimate condition based on direct evidence from the fossil record are ambiguous due to inadequate fossil evidence for the earliest haplorhines. Seven recently discovered, isolated distal phalanges from four early Eocene localities in Wyoming (USA) closely resemble those of the pedal dpII in extant prosimians. On the basis of faunal associations, size, and morphology, these specimens are recognized as the grooming phalanges of five genera of haplorhine primates, including one of the oldest known euprimates (∼56 Ma), Teilhardina brandti. Both the phylogenetic distribution and antiquity of primate grooming phalanges now strongly suggest that ancestral euprimates had grooming claws, that these structures were modified from a primitive claw rather than a flat nail, and that the evolutionary loss of ‘grooming claws’ represents an apomorphy for crown anthropoids.

The Palaeoryctidae are a group of small-bodied, likely insectivorous mammals known principally from the Paleocene and early Eocene (from approximately 65 to 53 Ma) of North America. Here we report on a new palaeoryctid from the early Eocene (early Wasatchian (Wa3) North American Land Mammal Age) Main Body of the Wasatch Formation, Washakie Basin, near Bitter Creek station in southwestern Wyoming, USA. Acerorcytes dulcis gen. et sp. nov. is unique among palaeoryctids in having a double-rooted P2 with a small anterior cusp, P3 with pronounced para- and metastylar cusps and a reduced but conspicuous metacone, P4 with a weakly developed metacone and an anteroposteriorly compressed protocone, and M1-2 with deep ectoflexus and a sharp metastylar blade. A phylogenetic analysis based on 32 dental characters of the nine known North American palaeoryctid species, including Aceroryctes dulcis, recovered eight equally parsimonious cladograms. Similar to prior studies, the analysis suggests that the genus Palaeoryctes is non-monophyletic, with Palaeoryctes cruoris and Aaptoryctes ivyi closely related. Aceroryctes dulcis is grouped with Ottoryctes winkleri and positioned in a more inclusive clade with Eoryctes melanus; the remaining palaeoryctid taxa, including Lainoryctes youzwyshyni, are part of an unresolved polytomy. These new findings indicate that early Eocene palaeoryctids were more diverse than previously thought, with genus richness during the early Eocene at least as great as that during the middle Paleocene.

The McKittrick tar seeps, located along the eastern foothills of the Temblor Range in the southern San Joaquin Valley of California (Kern County), are part of a vast complex of oil, gas, and tar se...

Here we report on late Pleistocene fossil vertebrates from new and previously described localities in Santa Clara County, California. The three new localities and specimens include: a partial mammoth pelvis from UCMP V91128 (Lawrence Expressway E); a juvenile cranial specimen of Mammuthus columbi from UCMP V99597 (SCVWD “Lupe” Mammoth), now on display at the San Jose Children’s Discovery Center; and a relatively diverse assemblage of medium- to large-sized mammals, including a nearly complete forelimb of Paramylodon harlani from UCMP V99891 (Babcock’s Bones). We also reassess specimens and assemblages from the following eight previously known localities: Molecular Medicine Building (UCMP V90003); Alma Street Underpass at Page Mill Road (USGS M1203); Mountain View Dump (USGS M1227); Sunnyvale Sewer (USGS M1218); Calabaza, Sunnyvale Sewer (USGS M1218A); Matadero Creek (USGS M1001); Matadero Creek, Veteran’s Hospital (USGS M1202); and Milpitas (UCMP V4916). All localities discussed, except Matadero Creek and Veterans Hospital, are mapped in areas with surficial Holocene deposits, and therefore, these Pleistocene-aged assemblages suggest that Pleistocene deposits are closer to the surface in Santa Clara County than may have been previously thought. Material described here highlights the needed resources for mitigation management in Santa Clara County.

Ectotherms have close physiological ties with the thermal environment; consequently, the impact of future climate change on their biogeographic distributions is of major interest. Here, we use the modern and deep-time fossil record of testudines (turtles, tortoises, and terrapins) to provide the first test of climate on the niche limits of both extant and extinct (Late Cretaceous, Maastrichtian) taxa. Ecological niche models are used to assess niche overlap in model projections for key testudine ecotypes and families. An ordination framework is applied to quantify metrics of niche change (stability, expansion, and unfilling) between the Maastrichtian and present day. Results indicate that niche stability over evolutionary timescales varies between testudine clades. Groups that originated in the Early Cretaceous show climatic niche stability, whereas those diversifying towards the end of the Cretaceous display larger niche expansion towards the modern. Temperature is the dominant driver of modern and past distributions, whereas precipitation is important for freshwater turtle ranges. Our findings demonstrate that testudines were able to occupy warmer climates than present day in the geological record. However, the projected rate and magnitude of future environmental change, in concert with other conservation threats, presents challenges for acclimation or adaptation.

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.

(2009). Differentiation of Phiomys andrewsi from Lavocatomys aequatorialis (n. gen., n. sp.) (Rodentia: Thryonomyoidea) in the Oligo-Miocene interval on continental Africa. Journal of Vertebrate Paleontology: Vol. 29, No. 4, pp. 1331-1334.

[Extract] Paleogene micromammal-bearing deposits from Afro-Arabia have until recently been largely restricted to a limited number of localities in Saharan Africa and Oman (e.g., Osborn, 1908; Wood, 1968; Jaeger et al., 1985; Fejfar, 1987; Thomas et al., 1989; Holroyd, 1994; Seiffert et al., 2008; but see also Gunnell et al., 2002). Research in the Rukwa Rift Basin of Tanzania has begun to reveal a diverse late Paleogene vertebrate fauna below the equator. This work has produced evidence of primate (Stevens et al., 2005), macroscelidean (Stevens et al., 2006a) and hyracoid mammals, and in particular, an interesting array of rodent taxa (Stevens et al., 2008). Teeth attributed to the phiomorph rodent Metaphiomys have been recorded in the study area (Stevens et al., 2006b), along with a number of smaller thryonomyoid rodent specimens, many of which are severely worn, hampering precise taxonomic assessment. The recent discovery of a fairly complete, modestly worn thryonomyoid mandible allows us to recognize the presence of a new taxon from the Rukwa Rift Basin deposits. This find is significant in that it represents the first novel Paleogene rodent genus and species described from East Africa, and documents a critically under-represented temporal gap in African faunal evolution (e.g., Seiffert, 2006).

KRISTER T. SMITH,",* BHART-ANJAN S. BHULLAR,2't and PATRICIA A. HOLROYD3; 1Vertebrate Paleontology Lab, J. J. Pickle Research Campus, 10100 Burnet Rd. Bldg. 6, The University of Texas, Austin, U.S.A.; 2Department of Geological Sciences, 1 University Station Stop C1100, The University of Texas, Austin, U.S.A.; 3University of California Museum of Paleontology, 1101 Valley Life Sciences Building, University of California, Berkeley, U.S.A.

Large-bodied, semiaquatic herbivorous mammals have been a recurring component of most continental ecosystems throughout the Cenozoic. Identification of these species in the fossil record has largely been based on the morphological similarities with present-day hippopotamids, leading to the designation of this pairing of body type and ecological niche as the hippo ecomorph. These morphological characters, however, may not always be diagnostic of aquatic habits. Here, enamel δ13C and δ18O values from living hippopotamuses were examined to define an isotopic signature unique to the hippo ecomorph. Although δ13C values do not support unique foraging habits for this ecomorph, living and fossil hippopotamids typically have low mean δ18O values relative to associated ungulates that fit a linear regression (δ18Ohippopotamids = 0.96 ± 0.09·δ18Ofauna − 1.67 ± 2.97; r2 = 0.886, p < 0.001). Modeling of oxygen fluxes in large mammals suggests that high water-turnover rates or increased water loss through fece...

Proton Induced X-ray Emission (PIXE) analysis of thirteen Late Cretaceous (hadrosaurid, tyrannosaurid, and Tyrannosaurus) and Early Jurassic (Dilophosaurus) dinosaur bones, two Late Cretaceous crocodylians, one plesiosaur, and three modern archosaurs (Rhea and Caiman), documents micron-scale diagenetic patterns of elemental uptake and loss. PIXE detected Al, Si, P, S, Cl, K, Ca, Ba, Mn, Fe, Sr, Y, and Nd at levels > 1000 ppm; and Ti, Cr, Ni, Zn, As, Zr, and U at trace amounts 100% of modern. This enrichment may reflect the migration of Ca and P between the hydroxylapatite matrix and the surrounding sediment after death, resulting in early diagenetic loss followed by uptake and recrystallization on crystallite surfaces. The elemental composition of fossil bone from the Early Jurassic dinosaur Dilophosaurus is distinguished by elevated As ppm, generally not present in the Late Cretaceous dinosaurs. We suggest that As is adsorbed from the reductive dissolution of As-rich iron oxyhydroxides in the local aquifer and is not reflective of Mesozoic atmospheric conditions or arsenic toxicosis in dinosaurs. PIXE allows us to reaffirm that the histological structure, tissue density, and high surface area of the vascular canals of dinosaur Haversian bone affect postmortem elemental enrichment and depletion and to quantify these differences at scales as small as 1.5 μm.

Chelonians are ectothermic, with an extensive fossil record preserved in diverse palaeoenvironmental settings: consequently, they represent excellent models for investigating organismal response to long-term environmental change. We present the first Mesozoic chelonian taxic richness curve, subsampled to remove geological/collection biases, and demonstrate that their palaeolatitudinal distributions were climate mediated. At the Jurassic/Cretaceous transition, marine taxa exhibit minimal diversity change, whereas non-marine diversity increases. A Late Cretaceous peak in ‘global' non-marine subsampled richness coincides with high palaeolatitude occurrences and the Cretaceous thermal maximum (CTM): however, this peak also records increased geographic sampling and is not recovered in continental-scale diversity patterns. Nevertheless, a model-detrended richness series (insensitive to geographic sampling) also recovers a Late Cretaceous peak, suggesting genuine geographic range expansion among non-marine turtles during the CTM. Increased Late Cretaceous diversity derives from intensive North American sampling, but subsampling indicates that Early Cretaceous European/Asian diversity may have exceeded that of Late Cretaceous North America., Turtles are ectothermic vertebrates that have experienced major environmental perturbations. Here the authors show that the geographical distribution of turtles was mediated by climate throughout the Mezozoic and show an increase in diversity of non-marine turtles starting in the Early Cretaceous.

(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.

SYNOPSIS Recent expeditions in the Pondaung Formation have revealed an assemblage of hyaen‐odontid creodonts from the late middle Eocene of Myanmar. Among the three proviverrines known from the fauna, Kyawdawia lupina gen. et sp. nov. is represented by the most complete dental materials. Kyawdawia is similar to the proviverrines known from the Eocene and middle Miocene of India‐Pakistan and from the late Eocene to middle Miocene of Africa, in that it has a short protocone and strong buccal cingulum on M1–2, a small metaconid on m2–3 and a well‐basined talonid on p4‐m2. In addition, it lacks an anterior accessory cusp on p4 and the distinction between the hypoconulid and entoconid on the lower molars. It is unique among the Afroasian proviverrines in lacking a protocone lobe on P4 and in having a broader paracone relative to the metacone on M1–2. This species is one of the largest proviverrines and was estimated to be the size of a red wolf. The type specimen includes postcranial materials. The well‐develo...

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.

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

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.

The Gray-faced Sengi (Rhynchocyon udzungwensis) is a newly-discovered species of sengi (elephant-shrew) and is the largest known extant representative of the order Macroscelidea. The discovery of R. udzungwensis provides an opportunity to investigate the scaling relationship between brain size and body size within Macroscelidea, and to compare this allometry among insectivorous species of Afrotheria and other eutherian insectivores. We performed a spin-echo magnetic resonance imaging (MRI) scan on a preserved adult specimen of R. udzungwensis using a 7-Tesla high-field MR imaging system. The brain was manually segmented and its volume was compiled into a dataset containing previously-published allometric data on 56 other species of insectivore-grade mammals including representatives of Afrotheria, Soricomorpha and Erinaceomorpha. Results of log-linear regression indicate that R. udzungwensis exhibits a brain size that is consistent with the allometric trend described by other members of its order. Inter-specific comparisons indicate that macroscelideans as a group have relatively large brains when compared with similarly-sized terrestrial mammals that also share a similar diet. This high degree of encephalization within sengis remains robust whether sengis are compared with closely-related insectivorous afrotheres, or with more-distantly-related insectivorous laurasiatheres.

(2003). The antiquity of African tortoises. Journal of Vertebrate Paleontology: Vol. 23, No. 3, pp. 688-690.

The condylarths, or archaic ungulates, are a paraphyletic mammalian group including a number of fossil taxa whose relationships are unresolved. Included are two genera from the Paleocene and Eocene of North America, Meniscotherium and Phenacodus. Some workers place both genera in the family Phenacodontidae, while others exclude the highly dentally derived Meniscotherium. In this study, we use growth increments in histological thin sections to examine the timing of crown formation in five molars of Meniscotherium and one each of Phenacodusintermedius and Phenacodus trilobatus. We also use perikymata counts on an additional six molars of Meniscotherium. Although estimated body mass and molar dimensions in Meniscotherium are smaller than in either species of Phenacodus, molar formation times are longer, ranging from 0.71 to 1.44 years. Both Phenacodus molars take less than a year to form. Crown extension rates, the rate at which the crown grows in height, are as low as 3-15 microm per day in Meniscotherium, but range from 13 to 54 microm per day in Phenacodus. Although striae periodicities and daily enamel secretion rate are similar in both genera, the differences in the crown extension rate and overall timing of crown formation suggest differences in life histories and raise questions about the phylogenetic relationship of the two genera.