Harvestmen are common elements of the modern-day fauna, however, the fossil record of harvestmen is sparse, with only about 50 fossil species in comparison to almost 7000 extant species. A new fossil harvestman (Arachnida, Opiliones) is described here, from Eocene Baltic amber. While having common harvestmen features such as elongated legs with highly subdivided tarsi, the specimen exhibits a unique feature on the pedipalps in the form of an additional element, possibly representing a subdivided tarsus. Such a pedipalp morphology is so far unknown in both modern and fossil representatives of Opiliones. It highlights a rare morphological singularity in Opiliones and complements the sparse fossil record of harvestmen preserved in amber. The massive pedipalps resemble those of armoured harvestmen (Laniatores), yet the specimen is more likely a representative of Phalangiidae. The additional joint in the pedipalps of the newly described specimen possibly allowed it to catch small-sized prey.

We present a multi-proxy geochemical analysis of proboscidean and equid teeth from a newly-documented Blancan (Pliocene–Pleistocene) locality in north-western Mexico. Eleven dental elements (six from equids and five from gomphotheres) were analysed by electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and isotope ratio mass spectrometry (IRMS) to assess preservation and reconstruct palaeoecological and palaeoclimatic patterns. All specimens show excellent microstructural integrity, with stable Ca/P and F/P ratios indicating near-stoichiometric hydroxyapatite and excellent preservation. Trace-element concentrations (Sr, Ba) and flat, PAAS-normalised REE+Y profiles indicate minimal diagenetic overprint, permitting the retention of biogenic signals. Stable carbon isotope values (δ 13 C diet,meq ) reveal predominantly mixed C 3 –C 4 feeding strategies, with proboscideans consuming proportionally more C 4 vegetation than equids. The latter exhibit higher Ba/Ca and Sr/Ca ratios despite lower δ 13 C diet,meq enrichment, suggesting selective feeding or height-related browsing. Mean annual precipitation (MAP ≈ 125 mm/year), derived from δ 13 C diet,meq values, indicates arid conditions within the envelope expected for semi-arid to arid ecosystems documented for the late Neogene–early Quaternary across North America and other regions worldwide. Oxygen isotope compositions (δ 18 O) imply similar climatic settings amongst taxa, with interindividual variability linked to physiology, mobility or access to distinct water sources. Mean annual temperature (MAT ≈ 15 °C) agrees with independent proxies and is consistent with late Pliocene conditions warmer than present. These results provide the first quantitative reconstruction of Blancan terrestrial climate in north-western Mexico, offering new insights into mammalian ecological adaptations and environmental dynamics during the Pliocene–Pleistocene transition.

Triassic strata in the portion of the Central European Basin (CEB) that cover parts of conterminous Germany have yielded a long if discontinuous record of continental tetrapods spanning this period. The classic Germanic Triassic succession comprises two mostly terrestrial units, the Buntsandstein and Keuper groups, separated by the predominantly marine Muschelkalk Group (Fig. 1). Thus, it is not possible to trace lineages of terrestrial tetrapods continuously through the entire Triassic Period. Skeletal remains of Early and early Middle Triassic (Induan-early Anisian) reptiles are rare in the Buntsandstein Group and mainly known from the Upper Buntsandstein Subgroup. The Middle Triassic (Anisian-Ladinian) marine carbonates of the Muschelkalk Group have yielded a considerable diversity of sauropterygians together with a few ichthyopterygians, a possible thalattosaurian, and the long-necked tanysaurian archosauromorph Tanystropheus . The late Middle and Late Triassic continental deposits of the Keuper Group preserve a substantial record of the rapidly diversifying crocodile-line and bird-line archosaurs together with stem-forms of some tetrapod crown clades such as turtles and lepidosaurs. In recent years, many new discoveries have greatly increased our knowledge of reptiles from the Keuper Group, especially from the Ladinian-age Lower Keuper Subgroup. The latest Triassic (Rhaetian) is represented by bonebeds containing bones and teeth of marine and continental vertebrates including reptiles that were deposited before the Early Jurassic transgression completely inundated the CEB. This paper provides a detailed overview of the currently known taxa of reptiles from the Triassic of conterminous Germany and explores some more general aspects of this fossil record.

Fossil insects have been a key tool for understanding the phylogeny and evolutionary history of life. However, many regions of the world still exhibit significant gaps in the knowledge of insect fossils, with South America being particularly underrepresented. The limited understanding of the fossil record—encompassing diversity pools, types of fossil evidence, geological ages, and taxonomic identity—can lead to the undervaluation of this heritage and, in severe cases, to the material loss of specimens. This study aims to provide a systematic compilation of studies on Chilean fossil insects and a fossil checklist. A broad literature review was conducted, including scientific articles, books, theses, and conference papers, using keywords related to Chilean fossil insects. We included data of species identity, fossil type, stratigraphic context, age calibrations, and locality information. The resulting dataset comprised 93 works, including 65 primary and 28 secondary sources. We registered records from Quaternary, Neogene, Paleogene, Cretaceous, Jurassic, and Carboniferous periods. The Quaternary period had the most extensive coverage in terms of fossil records. A total of 726 nominal records (taxon and ichnotaxon names) of arthropod fossils were recorded, with Coleoptera the most diverse group. Additionally, 17 records of Araneae and one putative record for Myriapoda classes were registered. Finally, we critically evaluated the sources of information to confirm or dismiss some doubtful records, provide an overview of the current state of knowledge, and suggest considerations for the future development of this discipline in Chile. Future studies should consider new methodological approaches, validate the records through thorough phylogenetic and nomenclatural analyses, properly characterize the type of material and its compliance with current nomenclatural rules, and finally, provide an accessible repository to ensure the replicability of the studies.

The fossil record of plesiosaurs, while extensive, is strongly affected by geological and anthropogenic biases that may obscure true diversity patterns. This study evaluates the influence of rock availability and sampling effort on taxic diversity estimates (TDE) of plesiosaurians throughout the Mesozoic period and proposes a method for determining priority stages for future fossil sampling. Two primary proxies—the number of fossiliferous marine formations (FMF) and fossil marine collections (FMC)—are considered. Our findings indicate that neither FMF nor FMC alone accounts for observed diversity peaks and troughs in plesiosaurian TDE. To address this, we integrate phylogenetic diversity estimates (PDE) into our framework, using the difference between PDE and TDE (i.e., phylogenetic residuals) to identify stratigraphic stages where recorded diversity likely underrepresents true lineage richness. This combined approach reveals that some previously recognized declines in TDE—such as during the Berriasian—are consistent with low sampling proxy values and may reflect genuine sampling bias. In contrast, other intervals, particularly the Aalenian–Bathonian, Valanginian and Coniacian ages, exhibit low TDE despite limited rock and collection data but high phylogenetic residuals, highlighting them as high-priority targets for future paleontological fieldwork. These stages represent critical intervals for testing the consistency between diversity models based on sampling proxies and phylogenetically inferred diversity trends.

The zombie worm genus Osedax Rouse et al. 2004 is part of a peculiar group of organisms that thrive at whale fall localities on the ocean floor. In addition to feeding on whale bones, extant Osedax spp. are known to feed on the bones of other marine and terrestrial mammals, birds, and reptiles, and have recently been found to also feed on shark tooth dentine under experimental conditions. The efficacy of Osedax spp. as bioeroders is such that they are thought to have significantly affected both the quantity and the quality of the marine vertebrate fossil record. Here, we report on the occurrence of single-entry borings consistent with those produced by Osedax on fossil shark teeth from the Lower Pliocene offshore deposits of Tuscany, central Italy. Micro-CT investigations reveal that the worms excavated the dentine of the tooth roots, leaving the enameloid-coated crowns seemingly unaltered. The borings in question are assigned to the Osedax -related ichnogenus Osspecus Higgs et al., 2012, which to date had been found on a variety of marine vertebrate fossils, but not on shark teeth. This ichnological record provides the first fossil evidence for zombie worms exploiting shark tooth dentine and serves as a powerful demonstration that such behaviour can and does occur in the wild. Root exploitation by Osedax may contribute to explain the high frequency of rootless teeth in some shark tooth accumulations from modern deep-sea floors and time-averaged horizons inland. Over the past 100 million years, shark teeth have likely served as critical ecological stepping stones between remote marine vertebrate fall localities and may even have provided a suitable substrate for ancient zombie worms during the Cretaceous–Paleogene (K–Pg) extinction event.

Members of the Aspidorhynchidae, an extinct family of ray-finned fish (Actinopterygii) are amongst the most common larger predatory fish in the Late-Jurassic Solnhofen Archipelago. Aspidorhynchids from these localities have yielded specimens with prey fish stuck in their mouths and stomachs. We report here on isolated skulls and, in one case, a body fragment of Aspidorhynchus with attached gastrointestinal tract, whereas all other parts of the body of these specimens are missing. These extraordinary fossils are probably feeding-remains left over by larger predators, apparently unique in the fossil record and even for the Solnhofen Archipelago something special that is hardly known. As proof that these diffuse appendices to the cranium are gastrointestinal tracts, we show here for the first time prey fish and, in one case, a crustacean visible in some of these gastrointestinal tracts.

A new crocodylomorph fossil specimen (ML2631) from the Upper Jurassic of Lourinhã (Portugal) is described, based on a partially preserved skull table and braincase. The specimen was recovered from the Zimbral vertebrate microfossil assemblage, located in the lower part of the Praia Azul Member of the Lourinhã Formation (Kimmeridgian–Tithonian transition). The fossil was scanned using high-resolution micro-computed tomography (µCT), enabling the digital reconstruction of internal cranial structures, such as the brain cavity, cranial nerves, inner ear and paratympanic sinus system. These reconstructions represent the first neuroanatomical data ever reported for Atoposauridae, a clade of small-bodied neosuchian crocodylomorphs common in the Late Jurassic and Cretaceous of Europe. Phylogenetic analysis places ML2631 within Atoposauridae and contributes to resolving previously uncertain relationships within the group. Although fragmentary, ML2631 exhibits a unique combination of anatomical features, including a dorsolaterally open cranioquadrate passage, a sagittal crest along the frontal and parietal, a large, posteriorly placed and septate choana, large supratemporal fenestrae with a distinct posterior fossa and a squamosal lobe bearing a discontinuous lateral groove. These traits, amongst others, distinguish ML2631 from all other known atoposaurid species. Additionally, its neuroanatomical proportions suggest a dwarf adult individual with low-frequency auditory sensitivity and moderate visual acuity, consistent with a primarily terrestrial or nearshore lifestyle, coherent with the depositional environment of the fossil site. Taken together, these results highlight the taxonomic and evolutionary relevance of the specimen and underline the importance of future discoveries of more complete material to confirm its systematic and phylogenetic status within Atoposauridae.

Alligatoroidea is the crocodylian superfamily that includes extant alligators, caimans and many related extinct taxa. Palaeogene North America offers a rich record of alligatoroid diversity representing more than a dozen forms. The Eocene-aged Hancock Mammal Quarry (HMQ, Clarno Formation, John Day Fossil Beds National Monument, central Oregon, USA) has yielded two crocodylian fossils, a right humerus and the anterior portion of a left lower jaw from an unknown alligatoroid. Though fragmentary, discrete morphological traits of the HMQ alligatoroid are shared with several contemporaneous alligatoroids, but the suite of character states is unique. Though its phylogenetic placement is uncertain, the presence of an alligatoroid in north-western North America, along with the biostratigraphic record of other Palaeogene alligatoroids and Asian floral and faunal associations of the HMQ suggest that an Asian origin for the taxon is plausible.

Herpetofauna, particularly amphibians and reptiles, exhibit high levels of endemism and distinct diversity pattern on Taiwan island. However, the biogeographic history of these groups remains obscure, in part due to the lack of a herpetofaunal fossil record. Here, we report the first fossil record of frogs and snakes from Taiwan, based on Middle Pleistocene vertebrate assemblage recovered from the Chochen–Tsailiao area in southern Taiwan. The collection includes a vertebra of a bufonid frog and multiple vertebrae of colubrid and viperid snakes. Despite their fragmentary preservation, several vertebrae are identifiable, including a toad (Duttaphrynus melanostictus), rat snakes (Ptyas mucosa and P. cf. mucosa), a wolf snake (Lycodon rufozonatum), and a pit viper (Protobothrops sp.). Additional vertebrae are attributed to Colubridae indet. and Alethinophidia indet. The preservation of these delicate skeletal elements in a tectonically active and humid subtropical setting highlights the exceptional nature of this discovery. Palaeoenvironmental reconstruction based on ecological preferences of extant analogues suggests that the region supported a humid fluvial and open woodland environment with abundant water bodies.