Anatomical Record-Advances in Integrative Anatomy and Evolutionary Biology最新文献

Facial expression is a key component of primate communication, and primates (including humans) have a complex system of facial musculature underpinning this behavior. Human facial musculature is highly variable across individuals, but to date, whether other primate species exhibit a similar level of inter-individual variation is unknown. Whether individual-level variation in facial musculature covaries with significant differences in facial movement within the same individual is also unknown. Here, we use facial dissection data from 31 adult rhesus macaques, the largest sample to date, to quantify inter-individual variation in facial muscle presence. We used a subsample of eight individuals to measure covariation between facial muscle presence and the presence of external facial movements (action units in the Facial Action Coding System, or FACS). We found, in contrast to humans, limited inter-individual variation in muscle presence, but the zygomatic region exhibited more gross anatomical variation in muscle presence and morphology than any other region of the macaque face. We also found a good correspondence between facial muscle presence and the presence of the associated action units. Our results indicate that the observed variation in rhesus macaque facial expressivity is not likely driven primarily by variation in facial muscle presence but may instead be due to other factors such as learned behavior and/or physiological differences. These findings provide insight into the anatomical basis of inter-individual variation in facial behavior in primates and suggest potential differences in variation between humans and other primate species.

This special volume, "New Paleontological Research in Turtles and other Vertebrates", pays tribute to the Spanish Researcher Dr. Emiliano Jiménez Fuentes, who passed away in December 2021. His role was fundamental for the development of the studies on the vertebrate faunas of the Spanish Eocene Duero Basin, as well as for the creation of the Collection of Fossil Vertebrates of the Duero Basin ("Sala de las Tortugas" of the University of Salamanca), which houses more than 25,000 specimens of vertebrates, including about 20 holotypes of mammals and reptiles. Since 1960 and over several decades, Dr. Jiménez Fuentes was the leading researcher in the study of Iberian fossil turtles. Fourteen scientific articles on various topics, related to his extensive professional career, are part of this volume. Representatives of several lineages of reptiles and mammals from the Duero Basin are analyzed, from systematic perspectives, but also considering other aspects of their paleobiology. Among them, a new eusuchian crocodyliform (i.e., Asiatosuchus oenotriensis) and a new hyaenodontid mammal (i.e., Prodissopsalis jimenezi) are included. Taxa from other ages and geographic regions, but with systematic affinities with those deposited in the "Sala de las Tortugas," are analyzed in other articles of this volume. Given the great interest of Dr. Jiménez Fuentes in the evolutionary history of Testudinata, several papers analyze members of this lineage, including the description of a new giant tortoise from the Miocene of Germany (i.e., Titanochelon schleichi), and that of a new marine cryptodire from Portugal (i.e., Lusochelys emilianoi).

Available paleontological evidence, although scarce, points to the early diversification of salientian lissamphibians in the Triassic and Early Jurassic. This study provides new key anatomical information on the earliest mostly articulated frog currently known, thereby improving our understanding of the early evolution of this lissamphibian lineage. Herein, available specimens of the Early Jurassic Vieraella herbstii from Patagonia, which consist of dorsal and ventral imprints of the incomplete, partially articulated skeleton of a single individual, are thoroughly redescribed. Although we comment on its known features, we focus on those that had been misinterpreted or overlooked previously. Among other features, we address the relative proportions of the skull regions and limbs, the morphology of the vomers, the peculiar articulation of the palatine flanges of premaxilla and maxilla that suggests the presence of well-developed cristae subnasales, and the presence of prepollex. The most surprising, significant findings are the presence of stapes, indicating the possibility of a complete tympanic middle ear, and of a short, tapering urostyle and postsacral vertebral elements. Based on available information, we present partial reconstructions of the pectoral girdle and the skeleton of Vieraella in the dorsal aspect. Discussion of the evolutionary significance of these features and perusal of the phylogenetic and functional analyses that included Vieraella in the taxon sampling highlight the necessity of thorough revision of the scorings and measurements, incorporating information presented herein. This reassessment will be relevant not only to clarify its relationships but also to provide sound insights into the early diversification of frogs.

The crania of leporid lagomorphs are uniquely fenestrated, including the posterior cranial bones and the lateral portion of the maxilla. The functional significance of the highly fenestrated rostrum has received considerably little attention, despite being absent in other mammalian herbivores with a long rostrum. This unique feature is of particular interest when considering functional relationships between the loading regime and cranial structure. Two primary hypotheses have been suggested: maxillary fenestrations may be associated with the transmission and redirection of incisal occlusal forces, or fenestrations may reduce skull weight to assist with maneuverability and increase running speed. Here we apply a comparative approach using finite element analysis to determine how the overall stress and strain environment is affected by the presence or absence of maxillary fenestrations. We compare three lagomorph species with various degrees of latticing in the fenestrated rostrum with two macropods that do not have fenestrations. We then produce theoretical models of the three lagomorphs by filling in the fenestrated region. Our results show that the presence of fenestrations makes little difference to the overall stress experienced through the cranium and does not impact the efficiency of incisor biting. This adds to the increasing evidence that features of lagomorph cranial morphology correlate with locomotor demands, adapting to loads other than mastication. Modulating cranial mass with fenestrations may provide the benefits of a lighter skull while still providing enough surface area for muscle attachments.

The Early Pleistocene fossil site of Schernfeld, a karst fissure filled with an ossiferous breccia, is well known due to the abundant fossil remains, mainly of micromammals and carnivores. Since the discovery, the taxonomic status of the Schernfeld mustelids has caused controversy and, consequently, various authors have listed different species. Until recently, none of these species has been the subject of adequate studies. A detailed revision of the Schernfeld mustelids material was made through comparative morphology based on mustelids from other European Early and early Middle Pleistocene sites. It reveals the presence of five mustelids: Gulo gulo schlosseri, Martes vetus, Meles meles, Mustela palerminea, and Mustela praenivalis. Their remains are characterized by ancestral features, especially in M. vetus, M. palerminea, and M. praenivalis. Due to the morphology of mustelids and the taxonomical composition of the Schernfeld fauna, the biochronological age of the entire assemblage was re-evaluated and assessed for ca. 1.9-1.7 mya.

Primates are often considered to have a poor sense of smell. While all studies identify small olfactory bulbs (OB; the region of the brain responsible for processing scent) among haplorhines, whether or not strepsirrhines also possess small OBs is less clear, as is the evolutionary backdrop from which these patterns emerged. Here, we examine the relative size of the olfactory bulbs in cranial endocasts of living and fossil primates and their kin (Euarchontoglires [Primates, Dermoptera, Scandentia, Rodentia, Lagomorpha]), testing previous hypotheses. Regression analyses of OB volume and mass relative to endocranial volume (ECV) and body mass (BM), and ANOVAS of residuals, were performed on a dataset of 181 extant and 41 extinct species. Analyses show clear differences in the relative size of the OBs, with haplorhines possessing distinctly smaller OBs relative to all other clades. Pairwise tests indicate haplorhine OBs are significantly smaller than those of all other clades, including strepsirrhines; when the haplorhines are removed from analyses, strepsirrhines are significantly smaller than all other clades. This suggests that a reduction in OB size occurred at the crown primate node, a pattern also seen in ancestral state reconstruction (ASR) analyses. The ASR analyses suggest multiple iterations of olfactory bulb size decrease occurred in Haplorhini, reflecting large amounts of parallelism. These results likely differ from previous studies due to the inclusion of additional fossils and more appropriate outgroups based on up-to-date phylogenetic hypotheses.

The oval window (OW) is an opening connecting the inner and middle ear. Its area has been shown to consistently scale with body mass (BM) in primates, and has been used alongside semi-circular canal (SCC) size to differentiate Homo sapiens and fossil hominins, including Paranthropus robustus. However, while the morphology of other inner ear elements, such as cochlea and SCCs, has been extensively studied in primates, OW shape has received little attention. In this study, we assess OW morphological variability in extant primates, and compare P. robustus to extant hominids. The potential of OW size to predict BM is also assessed. For this, measurements were performed on 3D scans from extant primate species and of P. robustus from the sites of Kromdraai, Swartkrans, and Drimolen. Size was assessed using perimeter (OWP), area (OWA), and centroid size (OWCS). Shape was assessed using geometric morphometric methods. The OW has no sexual dimorphism; there is no size difference between juveniles and adults, but there is a slight shape difference between human juveniles and adults, with a seemingly opposite ontogenetic trajectory compared to other primates. P. robustus has an intermediary OW shape between apes and humans, with more ape-like specimens from Kromdraai and more human-like ones from Drimolen. Overall, OW morphology discriminates primate species well enough, especially H. sapiens. BM is well explained by OWA, but OWA is not reliable as a BM proxy due to high prediction errors. Nonetheless, the OWA of P. robustus suggests a BM close to that of a chimpanzee.

The feet of people in non-industrial societies often have higher, stiffer longitudinal arches (LAs) and larger intrinsic muscles than those of many people in post-industrial societies. The prevailing explanation for this phenomenon is that people in post-industrial societies commonly wear shoes that restrict foot mobility, while people in non-industrial societies are often habitually barefoot or minimally shod. However, people in post-industrial societies also tend to be less physically active than in non-industrial societies, and it is possible that this, too, is a major determinant of their foot form and function. Here, we test the hypothesis that among people in post-industrial societies, lower physical activity levels are associated with lower, less stiff LAs and smaller intrinsic muscles. In a cross-sectional analysis of 40 adults in the United States, none of whom were habitually barefoot or minimally shod, we measured daily physical activity using accelerometry, LA height and static stiffness using photography, LA dynamic stiffness using kinematic and kinetic data, and intrinsic muscle size using ultrasound. Using Bayesian models, we found very low probabilities of positive associations between physical activity (step count, time spent in moderate-to-vigorous activity) and LA height, LA static stiffness, and muscle size. For LA dynamic stiffness, we found small to moderate probabilities of positive associations with physical activity variables. These findings suggest that physical activity is unlikely a major determinant of variation in LA and intrinsic muscle form and function among post-industrial societies. It remains possible that physical activity affects LA and intrinsic muscle traits, but perhaps primarily among people who are habitually barefoot or minimally shod.