Rachel H. Dunn

Dissection reports of large cats (family Felidae) have been published since the late 19th century. These reports generally describe the findings in words, show drawings of the dissection, and usually include some masses of muscles, but often neglect to provide muscle maps showing the precise location of bony origins and insertions. Although these early reports can be highly useful, the absence of visual depictions of muscle attachment sites makes it difficult to compare muscle origins and insertions in living taxa and especially to reconstruct muscle attachments in fossil taxa. Recently, more muscle maps have been published in the primary literature, but those for large cats are still limited. Here, we describe the muscular anatomy of the forelimb of the tiger (Panthera tigris), and compare muscle origins, insertions, and relative muscle masses to other felids to identify differences that may reflect functional adaptations. Our results reiterate the conservative nature of felid anatomy across body sizes and behavioral categories. We find that pantherines have relatively smaller shoulder muscle masses, and relatively larger muscles of the caudal brachium, pronators, and supinators than felines. The muscular anatomy of the tiger shows several modifications that may reflect an adaptation to terrestrial locomotion and a preference for large prey. These include in general a relatively large m. supraspinatus (shoulder flexion), an expanded origin for m. triceps brachii caput longum, and relatively large m. triceps brachii caput laterale (elbow extension), as well as relatively large mm. brachioradialis, abductor digiti I longus, and abductor digiti V. Muscle groups that are well developed in scansorial taxa are not well developed in the tiger, including muscles of the cranial compartment of the brachium and antebrachium, and m. anconeus. Overall, the musculature of the tiger strongly resembles that of the lion (Panthera leo), another large‐bodied terrestrial large‐prey specialist.

Although nonhuman remains constitute a significant portion of forensic anthropological casework, the potential use of bone metrics to assess the human origin and to classify species of skeletal remains has not been thoroughly investigated. This study aimed to assess the utility of quantitative methods in distinguishing human from nonhuman remains and present additional resources for species identification. Over 50,000 measurements were compiled from humans and 27 nonhuman (mostly North American) species. Decision trees developed from the long bone data can differentiate human from nonhuman remains with over 90% accuracy (>98% accuracy for the human sample), even if all long bones are pooled. Stepwise discriminant function results were slightly lower (>87.4% overall accuracy). The quantitative models can be used to support visual identifications or preliminarily assess forensic significance at scenes. For species classification, bone-specific discriminant functions returned accuracies between 77.7% and 89.1%, but classification results varied highly across species. From the study data, we developed a web tool, OsteoID, for users who can input measurements and be shown photographs of potential bones/species to aid in visual identification. OsteoID also includes supplementary images (e.g., 3D scans), creating an additional resource for forensic anthropologists and others involved in skeletal species identification and comparative osteology.

Artiodactyl postcrania are commonly used as paleoecological indicators but these studies are usually limited to artiodactyls within a single family. Here, we use 3D geometric morphometrics to analyze the morphology of calcanei from five artiodactyl families (Antilocapridae, Bovidae, Cervidae, Giraffidae, and Tragulidae) and identify common ecological trends among these families using principal component analysis. Our results indicate that antilocaprid and some bovid calcanei show convergent evolution of cursorial morphology and that other bovids have independently evolved less cursorial morphology that is more similar to cervids. This study shows that parallel ecomorphological trends can be identified in multiple families of artiodactyls, as well as within artiodactyl groups. This further suggests that the calcaneus may be a good indicator of ecology and function in fossil groups that are taxonomically ambiguous or not closely related to living taxa.

The anatomy of Cambaytherium, a primitive, perissodactyl-like mammal from the lower Eocene Cambay Shale Formation of Gujarat, India, is described in detail on the basis of more than 350 specimens that represent almost the entire dentition and the skeleton. Cambaytherium combines plesiomorphic traits typical of archaic ungulates such as phenacodontids with derived traits characteristic of early perissodactyls. Cambaytherium was a subcursorial animal better adapted for running than phenacodontids but less specialized than early perissodactyls. The cheek teeth are bunodont with large upper molar conules, not lophodont as in early perissodactyls; like perissodactyls, however, the lower molars have twinned metaconids and m3 has an extended hypoconulid lobe. A steep wear gradient with heavy wear in the middle of the tooth row suggests an abrasive herbivorous diet. Three species of Cambaytherium are recognized: C. thewissi (∼23 kg), C. gracilis (∼10 kg), and C. marinus (∼99 kg). Body masses were estimated from tooth size and long bone dimensions. Biostratigraphic and isotopic evidence indicates an age of ca. 54.5 Ma for the Cambay Shale vertebrate fauna, the oldest Cenozoic continental vertebrate assemblage from India, near or prior to the initial collision with Asia. Cambaytheriidae (also including Nakusia and Perissobune) and Anthracobunidae are sister taxa, constituting the clade Anthracobunia, which is sister to Perissodactyla. We unite them in a new higher taxon, Perissodactylamorpha. The antiquity and occurrence of Cambaytherium—the most primitive known perissodactylamorph—in India near or before its collision with Asia suggest that Perissodactyla evolved during the Paleocene on the Indian Plate or in peripheral areas of southern or southwestern Asia.

New dental and postcranial specimens of Pantolestes from the Uinta Basin, Utah, are described, and species-level diversity of Pantolestes from the Bridgerian and Uintan North American Land Mammal Ages is assessed. Because few morphological features can be found to distinguish species, we use size as the primary criterion for species membership. We recognize two species from the Bridgerian, P. longicaudus and P. natans. We consider P. elegans a junior synonym of P. longicaudus based on essentially identical size and dental morphology and include P. phocipes within P. natans based on the same criteria. Pantolestes intermedius is problematic, because the only known specimens are postcranial and pantolestids as a group show significant postcranial growth even after dental eruption is complete. However, its extremely reduced size relative to P. natans suggests that it is distinct from this species, and, although larger, it is closer in size to a referred specimen of P. longicaudus. We place all specimens of Uintan Pantolestes within either P. longicaudus or P. natans based on overall similarity in size and morphology. The postcranial remains of Uintan Pantolestes are fragmentary but show little morphological difference from earlier pantolestids. This suggests that Uintan pantolestids maintained an aquatic lifestyle despite the recession of ancient lakes in the continental interior occurring during that time. It is possible that the extreme rarity of Uintan pantolestids compared with earlier relatives is linked to the shrinking of aquatic habitats.

All domesticated mammals exhibit marked reductions in overall brain size, however, it is unknown whether the corpus callosum (CC), an integral white matter fiber pathway for interhemispheric cortical communication, is affected by domestication differentially or strictly in coordination with changes in brain size. To answer this question, we used quantitative magnetic resonance imaging to compare the midsagittal cross‐sectional areas of the CC in 35 carnivore species, including eight wild canids and 13 domestic dogs. We segmented rostro‐caudal regions of interest for the CC and evaluated correlations with brain mass. The results of this study indicate that under the influence of domestication in canids, the CC scales to brain size in an allometric relationship that is similar to that of wild canids and other carnivores, with relatively high correlation coefficients observed for all regions, except the rostrum. These results indicate that architectural and energetic considerations are likely to tightly constrain variation in caudal components of the CC relative to overall brain size, however fibers passing through the rostrum, putatively connecting prefrontal cortex, are less constrained and therefore may contribute more toward species‐specific differences in connectivity. Given the species diversity of the Canidae and the resurgence of interest in the brain of the domestic dog, further studies aimed at characterizing the neural architecture in domesticated species is likely to provide new insights into the effects of domestication, or artificial selection, on the brain.