Journal of Verterbrate Paleontology

Small mammals are a key study element for paleoenvironmental and paleoclimatic reconstruction, especially in the case of rodents due to their high adaptability. Their teeth play a crucial role in these studies for taxonomic assignment and the identification of taphonomic accumulation agents. Small rodent teeth, due to their size, are typically cleaned using chemical methods; however, this approach lacks precision and can harm materials. This study aimed to evaluate different cleaning methods on a sample of Meriones teeth with carbonate concretions from Kaldar Cave (Iran), not only to evaluate their efficacy, but also to characterise the possible modifications. The surface and composition of the samples were documented through microcomputed tomography and analysed before and after cleaning to identify any changes. Three cleaning reagents were tested based on sedimentary matrix and tooth composition: acetic acid, Tetrasodium ethylenediaminetetraacetic acid (EDTA), and sodium hexametaphosphate. These products were applied individually, in combination with mechanical cleaning and ultrasounds bath. Acetic acid and EDTA were the most successful in removing concretions, whereas sodium hexametaphosphate was less effective. However, the study revealed that these cleaning methods could cause some surface modifications, including scratches, volumetric losses, dentine displacement, opacity, and changes resembling digestion processes. These alterations must be considered when applying these methods to avoid interference with subsequent taphonomic or taxonomic studies.

A new long-snouted homodont odontocete fossil from the Lower Miocene of Austria (ca. 22.5–22.0 Ma) is formally described and interpreted based on external skull characteristics supplemented by CT and µCT data. The specimen was found in deposits from the Central Paratethys and includes an incomplete and fragmented cranium and mandible as well as ear bones. It differs markedly from previously identified long-snouted archaic dolphins with single- rooted, homodont dentition, and thus is suggestive of a new taxon, for which the name Romaleodelphis pollerspoecki proposed. The geological context of R. pollerspoecki hints at a neritic habitat in close vicinity to estuarine environments. Romaleodelphis pollerspoecki shares key features with certain members of the so-called ‘Chilcacetus clade’ such as the widening of the premaxillae at the rostrum base and the absence of a deep lateral groove along the rostrum; however, a phylogenetic analysis reconstructs R. pollerspoecki in a polytomy with members of this ‘clade’ and a larger clade including many other taxa. To better understand the phylogenetic relationships of these taxa, comprehensive reexamination of Argryocetus and Macrodelphinus will be necessary. Measurements obtained through µCT-based internal anatomical reconstruction of the bony labyrinth indicate that R. pollerspoecki had the ability to hear specialized high-frequency signals similar to modern narrow-band high-frequency (NBHF) specialists. This work further identifies several extinct platanistoids as hearing within the NBHF spectrum, increasing the understanding of the diversity of ecological adaptations in early-diverging odontocetes and providing more examples of convergent evolution of this hearing type.

Megadolodinae is a clade of tropical bunodont litopterns that includes three previously recognized species from Miocene fossil sites from northern South America. Here, we report an additional occurrence of Megadolodus molariformis from the Middle Miocene exposures at the Fitzcarrald arch (Peruvian Amazonia), based on dental material, which represents the southernmost record of the clade. This discovery further increases the faunal similarity between Fitzcarrald and the coeval La Venta fauna of Colombia. Given the convergent evolution of the bunodont dentition of megadolodines with suoids (Old World pigs and New World peccaries), we tested the hypothesis of frugivory in megadolodines with a mesowear angle approach using modern pigs and peccaries. These analyses differentiate the diet of modern suoids and suggest that megadolodines had a more abrasive diet than most of these taxa, except for the grazing warthogs. The dentition of megadolodines shows similar levels of abrasion to modern babirusas, thereby suggesting that the latter may represent an appropriate modern analog.

The diets and feeding strategies of pterosaurs remain a poorly known although speculatively debated topic in vertebrate paleontology. Fossilized gut contents, which offer a crucial direct line of evidence to help decipher these elusive questions, are only known from a handful of pterosaur specimens in a few notable fossil Lagerstätten, such as the Solnhofen Limestone of Bavaria. Although extremely rare, pterosaurs can be exceptionally well preserved in the Lower Jurassic (Toarcian) Posidonia shale of Baden-Württemberg but, until now, none have been reported with identifiable gut contents. Here, we describe fossilized gut contents in two Posidonia Shale pterosaurs: Dorygnathus banthensis (Rhamphorhynchidae) and Campylognathoides zitteli (Campylognathoididae). Dorygnathus is shown to be piscivorous as indicated by the inclusion of the small teleost Leptolepis sp. preserved inside of the abdominal cavity. The gastrointestinal tract of Campylognathoides preserves associated accumulations of belemnoid hooklets referrable to Clarkeiteuthis conocauda and thereby demonstrating a teuthophagous diet. These findings represent the first convincing evidence for belemnoids contributing to the diet of a pterosaur and hint at a possible nocturnal hunting behavior for Campylognathoides. Previous hypotheses regarding dietary trophic partitioning based on differentiating skull anatomy in Posidonia Shale pterosaurs are supported.

Several fragmentary remains of an enigmatic acipenseriform, the order of fishes that includes living sturgeons and paddlefishes, are described from the Upper Jurassic Kimmeridge Clay Formation of southern England. These remains are significant because they represent the first definitive evidence of an acipenseriform from the Upper Jurassic described outside of Asia. In total, five associated dorsal caudal fulcra from the caudal fin and a paired pelvic fin from at least two separate individuals are identified as acipenseriform, although it is uncertain to which family they belong. Three families of Mesozoic acipenseriform are considered: the †Chondrostei (Lower Jurassic, Europe), the †Peipiaosteidae (Upper Jurassic to Lower Cretaceous, Asia), and the extant Acipenseroidei (Lower Cretaceous-recent, Laurasia). The new Kimmeridgian Clay acipenseriform fossils would significantly extend the temporal and spatial distribution of whichever family they are ascribed, but their affinities remain unclear. Regardless, the stratigraphic and paleobiogeographic occurrence of the new specimens holds novel implications for the poorly known evolutionary history of this primitive clade of extant non-Neopterygian fishes.

Ornithocheiroidea was a globally diverse group of pterosaurs during the Cretaceous. However, well-documented ornithocheiroids are highly derived, hampering our understanding on the morphological evolution of this clade. Dsungaripterus weii Young, 1964 from the Lower Cretaceous Tugulu Group (Valanginian) of the Junggar Basin is an iconic early member of Ornithocheiroidea. Dsungaripterus is known from numerous three-dimensionally preserved specimens, ranging from isolated bones to partially articulated individuals. Here we provide a comprehensive description of the postcranium of Dsungaripterus. We find that Dsungaripterus has many autapomorphies in the postcranial skeleton parallelling its unique skull, including the asynchronous fusion between the sacrum and pelvis and a posterodorsal fossa of the humerus with a paper-thin bone wall. Dsungaripterus also displays some plesiomorphic features of Ornithoecheiroidea, for example, limb bones with relatively thick bone walls, variably reduced pneumatic features in cervical vertebrae and appendicular skeletons, absence of spinoprezygapophyseal and spinopostzygapophyseal ridges in middle-series cervical vertebrae, at least one metacarpal articulating with the distal syncarpal, and a distally displaced adductor ridge on the femur. Additionally, Dsungaripterus possesses some unexpected features possibly convergent with other members of Ornithocheiroidea. Although the postcranial skeletons of Dsungaripterus are represented by osteologically mature specimens, notable morphological variation is present. Functional reconstructions of several aspects of the postcranial skeleton of Dsungaripterus are elucidated, including the arrangement of the metacarpophalangeal region during terrestrial locomotion. Niche partitioning between the two dsungaripterids from the Tugulu Group of Wuerho, Dsungaripterus and Noripterus, is supported by their distinct dentitions, neck morphology, and limb proportions.

In this study, we describe a remarkably well-preserved cranium and stylohyoids of a large elephant from the Middle Pleistocene Pampore Member in the Karewas of Kashmir that was found associated with 87 stone tools. Based on the cranio-dental morphology, we assign the skull to the genus Palaeoloxodon, a lineage of massive elephants that evolved in Africa in the Early Pleistocene, and later dispersed across Eurasia. The skull possesses a combination of plesiomorphic and derived features of Palaeoloxodon, most notably, a broad, expanded frons and a nasal aperture with rounded margins that is characteristic of derived Eurasian Palaeoloxodon; but with an extremely underdeveloped parieto-occipital crest that is reminiscent of the basally branching African species, Palaeoloxodon recki. It is most similar in morphology to the type skull of Palaeoloxodon turkmenicus from Central Asia. The morphology of the stylohyoids is also different from those referred to Palaeoloxodon antiquus from Europe and Palaeoloxodon naumanni from Japan. While the validity of P. turkmenicus has been questioned in the past, this new specimen from Kashmir provides a strong case for a Middle Pleistocene species of Palaeoloxodon in Central and South Asia with intermediate morphologies between basally branching African species, and more derived Eurasian species.

We present a new taxonomic study of fossil giraffids from the Siwaliks of Pakistan. The recovered material belongs to the family Giraffidae and includes a cranium of Vishnutherium priscillum, maxillary isolated cheek teeth of Bramatherium grande, maxillary isolated cheek teeth and mandibular fragments of Bramatherium megacephalum. These specimens were collected from the localities of Dhok