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

Modularity and integration are key developmental properties and have remained central in evo-devo research because of how they relate to evolvability. While modularity and integration have commonly been assessed with landmark-based geometric morphometrics (GMM), other methods such as anatomical network analysis (AnNA) are increasingly being explored. Nonetheless, AnNA has seldom been used to assess variability within taxa, and there have been no attempts to verify whether its results are commensurate with GMM. We used the pectoral girdle of members of the Chrosomus eos-neogaeus hybridization complex as a case study system to assess differences between AnNA and GMM-based approaches and discuss how they should be best used. The general anatomy and composition of the pectoral girdle do not vary much within the complex; however, bones within the pectoral girdle show significant diversity in morphology and in the presence of sutures. Indeed, C. neogaeus displays characteristically enlarged coracoids and radials, and bone fusion between the cleithra, coracoids, and radials, while C. eos displays a gracile and unfused pectoral girdle. Hybrids display morphologies that are distinct from both parental species. AnNA detected multiple potential patterns of modularity, and GMM supported similar patterns of modularity across the complex but suggested different trajectories of morphological variation. Altogether, AnNA can be a valuable tool to formulate novel hypotheses in understudied taxa, which may then be tested using GMM, but careful morphological descriptions of skeletal systems are a valuable addition to the interpretation of both AnNA and GMM approaches.

Hybodontiformes was a diverse, successful, and important group of shark-like chondrichthyans known from a variety of ecosystems. Some representatives of the order had a wide palaeogeographic distribution, as is the case with Priohybodus arambourgi. With a multicuspidate crown, P. arambourgi was the first hybodontiform to develop fully serrated cutting edges on its teeth, a feature shared with many modern sharks (Neoselachii). Although Hybodontiformes comprises a group of early-diverging sharks with relevant diversity and abundance in different ecosystems across the Paleozoic and Mesozoic, the morphometry of preserved teeth has been weakly explored. Here, we present the first record of this taxon for the Aliança Formation (Tithonian) of the Tucano Basin, northeastern Brazil. The results demonstrated morphometric correlations of the features encompassed in the central cusp and lateral cusplets, indicating a non-allometric relationship in the increase of the crowns. P. arambourgi had a homodont dentition that preserves an ante-mortem wear pattern on the top of the central cusp, an important trait recognized as result for prey preferences. A comparison of the assemblages of P. arambourgi also demonstrates intraspecific variation among populations in Gondwana, indicating morphological plasticity of this species from Africa and South America. Finally, we compare the morphology of P. arambourgi with modern sharks, inferring the likely size, feeding mechanisms and prey preferences for a hybodontiform.

Siamogale melilutra was a large otter from the Late Miocene site of Shuitangba in Yunnan Province, China. Previous analyses have hypothesized that the species was a molluscivore and a dominant predator in an otherwise depauperate local carnivoran guild. Here we describe limb elements of S. melilutra and perform quantitative analyses to categorize the functional morphology of the species to better understand its role in the predominantly aquatic and near-water environments at Shuitangba. Our results indicate morphological similarities to both semi-aquatic and semi-fossorial modern mustelids. The limbs suggested unspecialized swimming abilities that were probably limited to paddling along the water surface. Multiple traits suggest semi-fossorial capabilities, possibly related to increased hip stabilization and postural maintenance during digging or intensive foraging. Features relating to semi-fossorial capability are consistently in the ranges of those of modern badgers. The combined functionality associated with both fore- and hind limb morphology was consistent with the more primitively generalized morphology of early lutrines. Many features of the limbs reveal the influence of body size that overwhelms or is indistinguishable from functional signals. Results suggest behaviors similar to those of the modern clawless otter Aonyx, which is more reliant on shoreline foraging, often involving digging, and terrestrial locomotion than other modern otters. The large size of S. melilutra likely provided advantages such as increased potential prey size range and the ability to utilize terrestrial resources, although it would have been more constrained by drag-related forces in the water.

Neuroanatomy studies in vertebrates have garnered significant attention in recent years, particularly driven by advancements in computerized tomography imaging techniques. Nonetheless, these advancements remain largely constrained to specific vertebrate groups, notably mammals, birds, and fish, leaving studies in reptiles at an incipient stage. In this work, we aim to describe in detail the macroscopic morphology of the brain of Crotalus durissus based on a sample of four young and four adult individuals—three male and five female specimens, providing the first detailed description of the brain with a relatively modest sample available for reptiles. Our results show that the major macroscopic features identified in C. durissus suggest a brain structure typical of a multi-habitat and cathemeral/nocturnal alethinophidian species, thereby contributing significant data to the understanding of brain morphological evolution in snakes. Brain measurements showed distinct scaling patterns related to snout-vent length and head length, with variables such as brain length and cerebral hemisphere length decreasing with SVL, while others like olfactory bulb length and medulla oblongata width increased. Additional differences were observed comparing juveniles and adults, with adults generally exhibiting larger mean values for cerebellum and medulla oblongata measurements. However, the small sample size highlights the need for future studies with larger datasets to validate these findings and explore the developmental trajectories in greater detail.

Neutrophil extracellular traps (NETs) are web-like, bactericidal structures produced by neutrophils and are composed principally of extracellular DNA, histones, elastase, and myeloperoxidase, among other components. NET formation is an innate immune response that is beneficial for pathogen killing and clearance. However, excessive NET formation and clearance defects can lead to inflammation and induce damage to host organs. NETs are also implicated in the development of noninfectious inflammatory disorders, such as liver injury in chronic liver diseases. The liver parenchyma contains hepatocytes, liver sinusoidal endothelial cells, Kupffer cells, and hepatic stellate cells. Each of these cells possesses unique structures and functions, and their interactions with NETs result in pathophysiological changes contributing to liver injury. This review updates the findings related to the modes of action and molecular mechanisms by which NETs modulate the pathophysiology of various hepatic cells and potentiate liver injury. The article also reviews the roles of NETs in hepatic ischemia reperfusion injury, hepatocellular carcinoma pathogenesis, and cancer metastasis. Last, we examine data to determine whether NETs induce crosstalk among various hepatic cells during liver injury and to identify future research directions.

Functional morphologists have long noted that skeletal adaptations in primate phalanges reflect locomotor behavior. While most studies have successfully used two-dimensional measurements to quantify general features of phalanx shape, a whole-bone three-dimensional analysis may better capture more subtle aspects of phalanx morphology that have not been quantifiable but are functionally meaningful. Here, we compare linear measurement (LM) and weighted spherical harmonic/sliding semilandmark (SPHARM-sliding) analyses of the manual third proximal phalanx (PP3) in extant hominoids (Homo, Pan, Gorilla, Pongo, Symphalangus, Hylobates; n = 292) and specimens attributed to Australopithecus afarensis (n = 2) and Homo neanderthalensis (n = 2). Morphological variation was summarized using principal component (PC) analysis. Differences between extant taxa were tested for using non-parametric MANOVAs (LM) and Procrustes distance resampling (SPHARM-sliding). Linear discriminant analyses (LDA) were performed using PC scores to assess whether the SPHARM-sliding or LM analysis better predicts group memberships of extant and fossil specimens. In both analyses, PC1 separates taxa along a locomotor gradient, and all extant genera are significantly different from one another (p ≤ 0.01) aside from Pongo versus Symphalangus in the LM analysis (p = 0.053). Only the SPHARM-sliding analysis found significant differences between taxa within each genus (p ≤ 0.04), and differences were even significant among Gorilla subspecies (p < 0.001). LDAs indicated that accuracy, separation effectiveness, and confidence were greater for the SPHARM-sliding analysis in predicting group membership among extant specimens, as well as fossil memberships to an extant group. Overall, results demonstrate that whole-bone, high-density landmark analyses can highlight nuanced features of PP3 morphology and may serve better for making inferences about fossils.

In this article, the discovery of Hyaenodon lingbaoensis, a new species of small Hyaenodontinae, is reported from the Middle Eocene Chuankou Formation in the Lingbao Basin of Henan province, China. The specimen is represented by a partial maxilla which preserves two deciduous premolars (DP3, DP4) and one molar (M1). The taxon can be assigned to Hyaenodon based on a “T-shaped” DP3; a small and low protocone on DP3-M1; and a buccolingually compressed and long metastylar blade on DP4-M1. The new taxon represents a basal Hyaenodon because it is more plesiomorphic than later members in having a M1 with a more developed paraconule and metaconule, a more enlarged protocone and less fused paracone and metacone. This finding casts new light on the early evolution of Hyaenodon and supports its Asian origin. Additionally, its deciduous and permanent premolars are described and new evidence regarding their replacement patterns of Asian Hyaenodon is provided.

Smilodon, the iconic saber-toothed cat, was a Pleistocene apex predator comprised of three morphologically distinct species: Smilodon fatalis, Smilodon gracilis, and Smilodon populator. While at Rancho La Brea (RLB) the paleobiology of S. fatalis is analogous to African lions in terms of carcass utilization, far less is known about S. fatalis outside of southern California. Further, Smilodon gracilis specimens are rare and less studied throughout most of its former range. This study expands our understanding of Smilodon's dietary ecology in North America by using dental microwear texture analysis (DMTA) to quantify carcass utilization and feeding behavior via complexity (Asfc) and anisotropy (epLsar) in populations of S. gracilis and S. fatalis from Florida, USA. Results reveal that S. fatalis populations from Florida and RLB have indistinguishable diets across climatically disparate regions during the Pleistocene. Additionally, S. fatalis and S. gracilis in Florida appear indistinguishable based on dental microwear textures, suggesting both species exhibited a generalist feeding strategy despite their temporal and morphological differences. Lastly, microwear in S. gracilis demonstrates a shift away from a tougher and potentially harder diet (epLsar and Asfc) during the glacial Inglis 1A site, as compared to the interglacial Leisey Shell Pit 1A site—similar to previously documented dietary shifts in glacial and interglacial populations of S. fatalis at RLB. Collectively, our findings are consistent with the hypothesis that the dietary behavior of S. fatalis and S. gracilis was generally consistent across space and time, with more subtle dietary differences occurring during glacial versus interglacial periods.

This special issue on Cartilage and Craniofacial Growth builds upon more than a century of work on the development of cranial cartilages. Illuminating work has been done in recent years on the cranial cartilages that serve as the template for much endochondral bone of the skull - the chondrocranium. With a focus on elements of the chondrocranium at the tissue level, the papers in this issue emphasize key characteristics of hyaline cartilage to skull morphogenesis. Based on matrix properties and cellular capabilities, cartilage is the ideal skeletal tissue for directional growth, but it also has multiple possible fates beyond its well-established importance as the source for endochondral components of the skull. In this issue, we have provided a greater focus on other fates, including persistence as cartilage or dictating the position of facial bones that are adjacent to cartilage which will disappear; that is, cartilage has both direct and indirect roles in facial morphogenesis. At the tissue level, cartilage is also important in a greatly prolonged temporal manner. Chondrogenic and osteogenic cells have a close relationship prior to differentiation, and endochondral bones have a long window of development time for change beyond the initial formation of a cartilage template.