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

Nasal turbinals are key osseous structures for air conditioning and olfaction in mammals, with their morphology reflecting both ecological adaptations and evolutionary history. This study evaluates how climatic gradients and locomotor strategy (subterranean or surface dwelling species) influence turbinal complexity in caviomorph rodents. Using microCT imaging, we quantified respiratory (RZ) and olfactory (OZ) turbinal morphology across eight caviomorph rodents and two outgroups from xeric, mesic, and generalist habitats, including subterranean and surface-dwelling species. Our results revealed that xeric-adapted subterranean species exhibited significantly expanded RZ surface areas and greater structural complexity, consistent with enhanced water retention demands in arid environments. While surface-dwelling species showed larger absolute OZ areas compared to subterranean taxa, this difference became non-significant after accounting for body size, suggesting olfactory structures are less influenced by locomotor strategy than by allometric or phylogenetic factors. Respiratory turbinals appeared more variable across habitats, whereas olfactory turbinals showed comparatively conserved morphology among ecological groups. This pattern could reflect differing evolutionary pressures acting on thermoregulatory versus sensory systems in rodents. The observed trade-off between respiratory efficiency and olfactory capacity suggests how multiple selective forces may shape anatomical specialization in response to environmental challenges. These findings provide new insights into functional constraints governing nasal evolution, proposing a framework for interpreting ecological adaptations in caviomorphs. Our study illustrates how integrating quantitative morphometrics with ecological data can elucidate complex structure–function relationships in mammalian anatomy.

Sabertooth creatures are fascinating to the public and to scientists. This Special Issue on The Anatomy of Sabertooths starts with a discussion of what exactly a sabertooth is, continues with a couple of papers about other animals with extraordinarily long teeth, and then delves into analyses of fossil sabertoothed taxa—some of which are not traditionally thought of as sabertooths and some of which are, but may not fit into the functional paradigm that we most associate with the sabertooth suite of morphology. The issue concludes with several studies that closely examine the function of the sabers themselves and then a final paper on one of the enduring mysteries about sabertooth anatomy that has nothing to do with their teeth at all. We proudly present this issue that has been years in the making and represents the work of scholars from around the world, all career stages, and experts in methodologies from traditional to cutting-edge, unified in our desire to bring you new and interesting insights into these taxa that continue to spark the imagination of budding future paleontologists and emeritus colleagues alike.

Caecilians comprise a relatively small (~220 species) group (Gymnophiona) of snake-like or worm-like, mostly tropical amphibians. Most adult caecilians are fossorial, although some species may live in aquatic or semi-aquatic environments, either as larvae or adults. Caecilians exhibit numerous morphological features traditionally interpreted as adaptations to their specialized ecologies, such as a compact and well-ossified skull and an elongated body lacking both girdles and limbs. Caecilian vertebrae differ substantially from those of other amphibians in having amphicoelous centra, well-developed basapophyseal processes, pronounced posterosagittal processes and hypapophyseal keels, and low and flat neural arches. However, caecilian postcranial osteology has received little attention, and the vast majority of the species remain unstudied. Consequently, the variation in the vertebral morphology among caecilians is still unknown or poorly documented. Inconsistencies in the anatomical terminology used by different authors are potentially confusing and may hamper understanding of homologies. Here we present an overview of caecilian postcranial osteology, define the main structural features, including many not previously described, and propose a standardized nomenclature.

Ribs undergo numerous changes during growth and development. Although they occur both externally and internally, the latter are not as extensively documented during the transition from puberty to adulthood. Therefore, it is unknown how rib cross-sectional mineralized area changes during this period. To shed light on this issue, we micro-CT scanned ribs from each costal level belonging to 21 individuals equally distributed into three developmental groups: pre-pubescents, post-pubescents, and adults. Then we selected the cross section at the midshaft of each rib and measured its percentage of mineralized area. Our results show that adults have lower mineralized area in their rib cross sections than both pre- and post-pubescents, which is consistent with previous research. Between pre- and post-pubescents, mineralized area is greater in the latter from costal levels 1–8. We propose that this might respond to a peak of mineralized area happening during late puberty. Regarding the tendency of the data, the three groups show a U-shaped trend with two maximum values at costal levels 1 and 12 and a minimum value at levels 4–5. We suggest that greater values are located at the beginning and the end of the costal series due to the mechanical stress produced in these areas by the scalene muscles (ribs 1–2) and diaphragm (ribs 7–12) during breathing. Interestingly, the U-shaped trend is less pronounced in pubescents, whose central costal levels have relatively more mineralized area than that of adults due to ongoing maturation from the external to central costal levels.

This study investigates the occurrence of osteomyelitis in non-avian dinosaurs, focusing on the Ibirá locality, a site with a high incidence of this pathological condition. We analyzed six new osteopathic sauropod specimens from the Upper Cretaceous of Brazil. The results revealed a relationship between infection and bone remodeling, denoted by various manifestations of reactive bone neoformation, including periosteal reaction. Healing tissues were not identified, which implies that the individuals died when the infection was still active. We described distinct manifestations of osteomyelitis with periosteal bone neoformation: (1) periosteal reaction within small circular protrusions; (2) ellipsoid protrusions in a fingerprint pattern; (3) enlarged protrusions both in height and area. This study underscores the importance of examining pathological conditions in extinct species to enhance our understanding of their physiology and interactions with their ancient environments.

Limb abnormalities are one of the most common deformities of vertebrates. They can be caused by both external and internal reasons. Limb abnormalities of amniotes are a fairly rare phenomenon, and mass limb abnormalities have not been found in amniote populations. Isolated cases of skeletal abnormalities are described mainly externally, without detailing the structure of the skeleton. This article presents descriptions of three abnormal specimens of hybrids of subspecies of Lacerta agilis (L. a. boemica × L. a. exigua). Two of them have oligodactyly of the right fore-limb. The third specimen demonstrates a unique combination of oligodactyly of the right and polydactyly of the left forelimbs.

China has been a rich source of fossils for nearly a century, beginning with the discovery of so-called Peking man (Sinanthropus pekinensis), known today as Homo erectus pekinensis in the mid 1920s. The first Chinese dinosaurs were described in 1929, the sauropod Helopus (now Euhelopus) and the ornithopod Tanius, described by the Swedish paleontologist Carl Wiman. Over the next six decades, further dinosaurs were described by Yang Zhongjian (C.C. Young) and his students Dong Zhi-Ming and Zhao Xijin, but remained poorly known in the West. A golden age of Chinese paleontology began as spectacular feathered dinosaurs were described from Lagerstätten in northeastern China beginning in 1996. Today, China has more genera of dinosaurs than any country on earth. In addition to dinosaurs and birds, China has among the oldest fossil vertebrates on earth with Cambrian fish such as Haikouella and Myllokunmingia, one of the first fossil flowers with Early Cretaceous Archaefructus, and a rich fauna of mammals, including Early Eocene Archicebus, one of the earliest known fossil primates. Fossil mammals range from a Jurassic beaver-tailed aquatic docodont, Castorocauda, to a Cretaceous gobiconodontid, Repenomamus, which had the nerve to munch on a baby dinosaur, to Ice Age elephants, woolly rhinoceros, horses, and saber-toothed cats. Surprising new fossils of all kinds will continue to be discovered in China for decades to come.

Since Raymond Dart's first attempt to identify the lunate sulcus (“Affenspalte,” simian sulcus) in a fossil hominin endocast—that of the Taung child (Australopithecus africanus)—paleoneurologists have debated this structure, which in the brains of monkeys and apes roughly coincides with the rostral boundary of the primary visual cortex. The classic view has been that the evolutionary expansion of the parietooccipital cortex “pushed” the lunate sulcus toward the back of the brain. However, there has been little consensus about how and when this might have happened during hominin evolution, as it has proven difficult to establish phylogenetic homology of potential lunate sulci in living humans with the lunate sulcus of great apes. Here we review the comparative neuroanatomical evidence and propose the hypothesis that the lunate sulcus underwent de-opercularization, that is, the structures buried within the sulcus expanded and became part of the external cortical surface. During this process, the lunate sulcus became shallow, fragmented, and eventually obliterated. Specifically, rather than migrating toward the occipital pole during brain evolution, the lunate sulcus was a hotspot for the evolutionary expansion of annectant gyri and their eventual emergence on the parietooccipital cortical surface. We test the de-opercularization hypothesis with an analysis of the parietooccipital endocranial region of early Homo from Dmanisi, Georgia, and conclude that in these fossils the lunate sulcus may have been in the evolutionary process of fragmentation as their brains became larger and their occipital lobes more caudally projected compared to earlier hominins.

The braincase and inner ear of the largest species of legless anguine lizards, Pseudopus apodus, are described in detail based on high-resolution x-ray microcomputed tomography. Here, the ontogeny of its braincase is briefly described. The detailed anatomy of the individual braincase bones of P. apodus is presented and compared with those of the modern anguine species Anguis fragilis and species of Ophisaurus, Dopasia, and Hyalosaurus. Because only the extant species of Anguinae are studied and discussed here, the generic names of modern taxa defined genetically—Ophisaurus (North America), Dopasia (Southeast Asia), and Hyalosaurus (North Africa)—are used here. The shape of the supraoccipital in juveniles was similar for all species found in all three geographic territories. During growth, the shape of the supraoccipital changes significantly in Pseudopus, Dopasia, and Ophisaurus, and its shape is very similar to that in adults of the anguine taxon Ophisauriscus quadrupes from the Middle Eocene of Germany. Instead, the shape of the supraoccipital in the adults of Hyalosaurus and Anguis is very similar to that in the juveniles of Pseudopus, Dopasia, and Ophisaurus. This suggests that paedomorphosis probably played a role in the shape formation of the supraoccipital in Hyalosaurus and Anguis. The morphological and proportional changes in several other braincase structures during ontogeny are also described.