Evolutionary Signal and Development of the Foramen Dorsum Sellae (Nov.) Across Primates

Linking form to function: a scoping review of the evolution of paranasal sinuses in mammals.

Evolutionary drivers of encephalization and facial reduction in the genus Homo

The evolution of cranial morphology in the genus Homo is marked by increasing encephalization and reduced facial robusticity through time. These changes are often assumed to be the product of directional natural selection for larger brain size, presumed to be associated with greater cognitive abilities, and for decreasing facial size to lower energetic costs, as masticatory demands were reduced through food processing and tool use. Here, we test this hypothesis by exploring the goodness-of-fit of the predictions of six evolutionary processes to the observed cranial morphological variation in Homo. We analyzed comprehensive neurocranial and facial 3D landmark coordinate datasets, grouped into eight Operational Taxonomic Units starting with early Homo and representing two lineages, Homo sapiens and Homo neanderthalensis. Our neurocranial analysis found strongest support for models of neutral evolution (Unbiased Random Walk) and stasis across both lineages. Similarly, the face shows strongest support for models of stasis, strict stasis, and neutral evolution (Unbiased Random Walk). Our findings suggest a limited role for gradual directional selection and underscore the importance of stabilizing selection and constraints in our lineage’s evolution, highlighting the importance of environmental constraints and possibly cultural behaviors as core drivers of human evolution. This study tests the evolutionary processes shaping the cranial morphology of the genus Homo. The authors report a limited role of gradual directional selection and underscore the importance of stabilizing selection and constraints in our lineage’s evolution.

THE SKULL BENEATH THE SKIN: CRANIAL OSTEOLOGY OF SKORPIOVENATOR BUSTINGORRYI (DINOSAURIA, THEROPODA, ABELISAURIDAE) FROM THE LATE CRETACEOUS OF PATAGONIA, ARGENTINA

In this study, we present a detailed comparative cranial anatomical description of the abelisaurid theropod Skorpiovenator bustingorryi. This specimen, recovered from the Cenomanian-Turonian Huincul Formation near the town of Villa El Chocón, Neuquén Province, northwestern Patagonia, Argentina, was thoroughly technically prepared and supplemented with CT scan-based reconstructions. Skorpiovenator represents one of the most complete abelisaurid skulls, and indeed one of the most complete of any South American theropod dinosaur documented to date. Its skull is moderately short and tall, featuring strongly ornamented facial bones, a characteristic common among abelisaurids. We re-evaluated previously proposed autapomorphies and suggest new ones to refine the diagnosis of the species. Furthermore, we discuss several cranial anatomical features, testing them within a phylogenetic framework to clarify its relationships among late branching ceratosaurians. The phylogenetic analysis conducted here recovers Skorpiovenator as a brachyrostran abelisaurid, nested within a subclade alongside other early Late Cretaceous Patagonian taxa. This subclade, in turn, forms the sister group to Furileusauria. Key cranial features discussed include the two pairs of prominences on the frontals, the low paired crests on the anterior portion of the nasals, the enlarged external mandibular fenestra, and its distinctive dentition. Notably, Skorpiovenator exhibits the highest maxillary and dentary tooth count recorded for an abelisaurid. A significant discovery is the identification of an additional small bone dorsal to the articular bone of the mandible, interpreted as the antarticular, which is likely sesamoid in origin. Although this bone has been reported only in the tetanuran theropod Allosaurus and is present in the craniomandibular articulation of extant birds, the element identified in Skorpiovenator represents the first record of such an ossification outside the Tetanurae lineage. The data presented in this work significantly enhance our anatomical understanding of abelisaurid crania and theropods in general, thereby contributing to a clearer understanding of phylogenetic relationships within ceratosaurian theropod dinosaurs.

Foraminal widening indicating a spinal nerve tumor in the saber-tooth cat Smilodon fatalis from Rancho La Brea

Tracing the health of extinct populations is important. Documenting this in deep time is challenging, but skeletal markers of disease can be preserved in fossils. Notably, a high incidence of spinal malformations has been recorded among specimens found in the La Brea Tar Pits, possibly because of an accumulation of expressed deleterious alleles that caused disturbances in developmental processes. The exceptional preservation of hundreds of specimens of the La Brea saber-toothed cat Smilodon fatalis allows us to examine pathologies within and across populations, with dire wolves from the same site and extant large-bodied felids serving as a basis for comparison. We identified three vertebral specimens from S. fatalis with changes indicating a possible spinal nerve tumor (SNT). The prevalence-like estimate was 353 per 100,000 individuals. The observed prevalence of foraminal widening compatible with presumed SNT among the La Brea S. fatalis sample appears high relative to reported human incidence estimates of 0.22–0.38 per 100,000 individuals, although these values are not directly comparable because the fossil estimate reflects skeletal occurrence in a taphonomically biased assemblage rather than clinical incidence. The reason for this high incidence in Smilodon fatalis is unclear, but in humans, many SNTs are associated with genetic mutations. Due to the presumed inbreeding toward the end of the species’ existence, a similar mutation could have contributed to the development of the presumed SNTs in S. fatalis.

Bumps, elongating noses, and abnormal skull bones: pseudo-neuroanatomy and Lombrosian Echoes in Collodi’s Pinocchio

Insights into Neanderthal development, childbirth, and locomotion from the Palomas and Dederiyeh pelves.

The human pelvis reflects evolutionary compromises among childbirth, bipedal locomotion, and other factors such as pelvic floor stability and thermoregulation. However, limited fossil evidence has hindered understanding of how these factors shaped pelvic morphology in Neanderthals, our closest extinct relatives. Here, we present new virtual reconstructions and morphometric analyses of nearly complete Neanderthal pelves from Sima de las Palomas del Cabezo Gordo (Spain) and Dederiyeh Cave (Syria), comparing them with other Neanderthals and modern humans. We find that Neanderthal and human pelves differ in overall shape from an early age but share similar sexual dimorphism patterns with humans. Pelvic regions associated with childbirth exhibit comparable functional morphology, suggesting similar birth mechanisms. Conversely, locomotor-related features such as hip joint orientation and muscle moment arm geometry differ, indicating distinct stance and gait adaptations. Our findings are consistent with the hypothesis that evolutionary constraints traditionally framed as an "obstetrical dilemma" may have involved a trade-off between childbirth and pelvic floor stability, rather than between childbirth and locomotor performance.