A paleontological deposit near San Clemente de Térapa represents one of the very few Rancholabrean North American Land Mammal Age sites within Sonora, Mexico. During that time, grasslands were common, and the climate included cooler and drier summers and wetter winters than currently experienced in northern Mexico. Here, we demonstrate restructuring in the mammalian community associated with environmental change over the past 40,000 years at Térapa. The fossil community has a similar number of carnivores and herbivores whereas the modern community consists mostly of carnivores. There was also a 97% decrease in mean body size (from 289 kg to 9 kg) because of the loss of megafauna. We further provide an updated review of ungulates and carnivores, recognizing two distinct morphotypes of Equus, including E. scotti and a slighter species; as well as Platygonus compressus; Camelops hesternus; Canis dirus; and Lynx rufus; and the first regional records of Palaeolama mirifica, Procyon lotor, and Smilodon cf. S. fatalis. The Térapa mammals presented here provide a more comprehensive understanding of the faunal community restructuring that occurred in northern Mexico from the late Pleistocene to present day, indicating further potential biodiversity loss with continued warming and drying of the region.

We describe here the topotypic series of Conohyus olujici n. sp. from the Croatian locality of Lučane. This sample was originally collected by local lignite miners in the 1930's, who conveyed the sample to the parish's Franciscan monk Dr. Josip Olujić. The Luč ane Conohyus sample includes seven lower jaws and jaw fragments; no upper cheek teeth have yet been recovered. Our use of bivariate statistics, log10 ratio diagrams and a cladistic analysis all reveal that C. olujici n. sp. is the most primitive member of the Conohyus clade. The analyses reveal that: of the sample considered, only two species are referable to Parachleuastochoerus, P. sp. and P. crusafonti; Parachleuastochoerus is the sister-taxon to Conohyus; Conohyus is a clade, and C. olujici n. sp. is the sister-taxon of the C. steinheimensis-C. simorrensis and C. sindiensis clades. Conohyus olujici n. sp. would appear to have occurred at a time when the genus enjoyed a relatively continuous geographic range that extended from southern Europe to South Asia. Conohyus olujici n. sp. was evidently adapted to swamp forest habitats. Its paleodiet, as evidenced by its thick molar enamel and labiolingually expanded posterior premolars, likely included hard object frugivory.

A thorough morphological description of Teleoceras material from the Gray Fossil Site, Gray, Tennessee is provided. This is the only record of a browsing Teleoceras and, as a late Hemphillian locality, represents one of the youngest populations. Linear measurements of post-cranial elements indicate proportional differences between Teleoceras from the Gray Fossil Site and those from other Hemphillian localities. These differences are more pronounced in the elements of the forelimb than in those of the hind limb. Statistical analyses of post-cranial elements from 3 Hemphillian species of Teleoceras suggest that these differences should not be used to separate species. However, the elements do typically sort well by fossil locality, which suggests that post-cranial morphology is plastic enough to become modified within a population. Furthermore, dental morphology comparisons with the holotypes of these species indicate that the GFS rhino represents a previously undescribed species.

Procyonids are well known biologically but knowledge of their fossil record is comparatively sparse. This study seeks to describe a sample of late Blancan procyonid fossils composed mostly of postcranial and dental material. Fossils are analyzed using linear and 2D geometric morphometrics and compared with a large sample of modern specimens from a wide geographic area to understand the range of intraspecific variation. The large Procyon species is described as a new taxon based on morphology of the postcrania and lower dentition, while another Procyon species is also described as new due to an apomorphy in the upper dentition. A new species of coati (genus Nasua) is identified and described based on lower dentition and postcranial morphology. The Blancan species P. rexroadensis is synonymized with P. lotor because the distinguishing dental feature for which the species is named is within the range of variation for P. lotor.

Here, a morphological description of the extinct meline badger Arctomeles dimolodontus from the Gray Fossil Site (GFS), Tennessee is provided with comparison to extant Meles meles. Originally described solely on upper teeth of a single individual, the recovery of several crania and jaws provides a sample of at least five individuals, affording the largest known fossil sample in North America of the enigmatic Melinae. Examination of A. dimolodontus skull material reveals extreme intraspecific variation in previously identified diagnostic characters, highlighting the need for caution when identifying fossil taxa based on similarly fragmentary remains. Dental variation is likely a result of hypocarnivory, and dentition may have become more complex over time in response to diet. Based on cranial characters, A. dimolodontus appears to be sexually dimorphic, similarly to extant badgers. Arctomeles dimolodontus has a complex auditory region with large bullae compared to M. meles, suggesting relatively heightened auditory sensitivity.

Snake vertebrae are common throughout the Cenozoic fossil record, but identification of isolated vertebrae often proves difficult due to inter- and intra-columnar variability. Most fossil identifications are based on comparisons with disarticulated modern specimens, with a focus on mid-trunk vertebrae. One focus of this study was to determine the necessity of identifying a true mid-trunk vertebra prior to identification and to develop a method of locating the columnar position of an isolated vertebra for both modern and fossil identifications. Colubrid genera Farancia and Heterodon were chosen for the analysis because they share distinct morphological similarities, articulated modern specimens were available, and fossil species in these genera need to be reassessed. Every third pre-cloacal vertebra was selected from each specimen to undergo geometric morphometric analysis on its anterior face. Relative warp analyses detailed the inter-columnar variation of each specimen and found that the only significant difference in the column was between the anterior most vertebrae, which are already identifiable, and the remainder of the pre-cloacal vertebrae. Despite concern, the convention of using mid-trunk vertebrae for identification may prove accurate for these genera. Due to Farancia and Heterodon’s vertebral similarities, a discriminant function analysis was utilized to distinguish the two genera from one another. To evaluate this method’s utility in paleontology, vertebrae of two extinct species, Heterodon brevis and Paleofarancia brevispinosus, will undergo identical morphometric and discriminant analyses. This study also emphasizes the need for more modern snake skeletons in collections and the necessity of stringing the vertebral column prior to disarticulation.

Through the last 60 million years (Ma) there were well-documented climate and habitat changes across North America. Continental and regional scale studies on ungulate (hooved mammals) tooth crown heights in relation to climate and habitat changes have documented an increase in tooth height as environments became more arid to combat a highly abrasive diet of fibrous plants and grit. Based on the relationships between crown height and climate, several studies have used taxon free methods to estimate past precipitation from fossil ungulates. Small mammals have also been shown to adapt to changing habitats, with specializations for life in open habitats appearing millions of years earlier than larger mammals. Utilizing taxon free methods, this study compared the crown heights of rodents and lagomorphs (rabbits and pika) from across North America to climate variables, including both temperature and precipitation. Studying small mammals allows examination of local changes to climate and can be informative of what is to be expected in regional communities if modern warming trends continue. Using ArcMap, modern climate data and mammal faunal lists for 100 random points were compiled and generated across North America. Crown heights of species were categorized and mean crown height for the community was calculated for each site. Linear regressions were used to examine the relationship between crown height and climate variables. Using ArcMap and ordinary kriging, maps were generated of predicted climate for all of North America and compared to known climate data. In general, the North-South gradient of temperature and the Northwest to Southeast gradient of precipitation was captured in predicted maps showing agreement with known climate maps. Regressions were also used to predict climate for 72 well-known fossil sites from the late Eocene (~37 Ma) to Pleistocene (~1.9 Ma) of North America, generating estimates of temperature and precipitation for many sites with no prior climate estimates. Results show strong correlation between rodent and lagomorph crown heights and temperature and precipitation variables. Temperature variables were more strongly correlated to tooth crown heights than precipitation. Overall, a decrease in precipitation and temperature was found across North America from 37 Ma to the present, consistent with prior paleoclimate records from other regional and global proxies. Application to detailed regional records from the Mid Miocene Climatic Optimum (around 15 Ma, during the early Barstovian land mammal age), which was a pronounced period of warming comparable to the warming we see today, showed regional variation in responses to warming. Tooth crown height increased in California and Nebraska before Oregon, showing climate did not change uniformly across North America similarly to what would be expected in modern warming. Using the method proposed in this study, past and future regional climate trends, as well as biotic responses to those changing climate trends can be better understood.

As ecologically sensitive organisms, freshwater mussels serve as environmental indicators in the rivers and lakes they inhabit. The South Fork of the Holston River has been impounded and channelized, which can result in habitat loss of riffle and shoal areas and negatively impact native species. The aim of this study is to analyze river conditions on a roughly 40 mile stretch of the S. Fork Holston River, encompassing the distance from Eastman Chemical Company in Kingsport to Boone Lake. Information has been gathered using mussel assemblages from two archaeological sites, 40SL34 and 40SL330, and two historic collecting events, SFHSkm25.1 and SFHSkm27.0. The computer program UNIO analyzes the ecological preferences of all input taxa to compile a list of river conditions, including flow velocity and substrate. Compiling the assemblages from all four sites has revealed an increase in unfavorable conditions for many species, leading to a loss in mussel diversity. What were once the most abundant species in the archaeological sites, Ptychobranchus subtentus and Fusconaia subrotanda, both prefer to live in riffle areas with fast current. Currently, P. subtentus is listed as endangered while F. subrotanda is listed as a special concern species. The most abundant species for both historic collecting events is Lampsilis fasciola, a species that is tolerant of conditions that are unfavorable for many species. The substrate of the S. Fork Holston River, a sandy-gravel, has remained the same, but evidence suggests that impoundment has resulted in the loss of fast-moving currents and riffle areas.

In this study, three new reports of large felids from the Pleistocene are presented and discussed. A single partial left dentary from Jawbone Cave represents the first confirmed presence of S. fatalis in east Tennessee and was sampled for radiocarbon dating. Wind Tunnel and Chilly Bowl Cave are among the first records of P. onca to be identified confidently from Arkansas. Chilly Bowl Cave also produced two trackways attributable to Panthera sp., one set potentially belonging to P. atrox. In addition to the description of these remains and the caves they were found in, taxonomic histories for both S. fatalis and P. onca are explored to explain the choice of name used for each felid. Regional reviews of material of each taxon are also presented.

Saber-toothed remains have been found worldwide throughout the Cenozoic, until the end of the Pleistocene. One site from Alachua County, Florida preserves a diverse Miocene fauna, including the machairodontine Nimravides galiani (Felidae) and the saber-toothed Barbourofelis loveorum (Barbourofelidae). Both taxa roamed what would become the Love Bone Bed site during the Late Miocene (Late Clarendonian NALMA), ~ 9.5 Mya. Previous descriptions focused on crania; yet the large sample of postcrania remained undescribed. Hence, this project includes a detailed postcranial description of both taxa. Results show that N. galiani resembles extant felids, whereas B. loveorum resembles Smilodon fatalis, as well as ursids. Additionally, locomotion and hunting behavior (prey capture) was examined quantitatively to assess ecologic overlap (niche partitioning vs direct competition). N. galiani probably displayed terrestrial locomotion in open habitats, whereas B. loveorum likely inhabited the deciduous forest as an ambulatory opportunistic/ambush predator. Results support niche partitioning, rather than direct competition.