New fossil anhingids from the upper Acre River (Late Miocene of southwestern Amazon)

Four extant species of anhingids are found worldwide, all belonging to a single genus (Anhinga). However, the fossil record reveals a much greater diversity of this group in the past. The oldest known anhingids date back to the upper Oligocene period in Australia, but during the Miocene epoch in South America, they achieved their most remarkable diversity. This study describes newly discovered anhingid fossils from the Late Miocene period in South America. These fossils were extracted from the Acre conglomerate member, part of the Upper Miocene deposits in the southwestern Amazon region. The described fossils consist of two fragments of pelvic girdles, two femora, and two vertebrae belonging to a giant anhingid (Macranhinga sp.), as well as a vertebra from Anhinga minuta, the smallest of all darters. The examination of these fossils suggests the presence of potentially three distinct anhingid taxa within the same locality. The environment in which the conglomerate deposits were formed was ecologically complex. It is likely that these three species coexisted within the same ecosystem but avoided direct competition for food and reproductive sites by not fully exploiting their fundamental niche.

Investigating the relationship between cranial bone thickness and diploic channels: A first comparison between fossil Homo sapiens and Homo neanderthalensis

Diploic veins are part of the circulatory system of the head. They transport venous blood and cerebrospinal fluid and are housed in diploic channels (DCs). DCs are highly variable in terms of their position, extension, and size. These parameters were hypothesized to be related to the variations in cranial vault thickness (CVT). For the first time, we analyzed the spatial relationship between CVT and DCs in a sample of eight H. neanderthalensis and H. sapiens cranial fossils. Using micro-CT scanning data, we constructed color maps of the CVT and visually inspected whether the regional thickness variation was associated with the morphology and distribution of the DC branches. The results showed that when regional bone thickness was below a certain threshold, no DCs or scattered small DC branches were present. Larger DC branches appeared only when the thickness exceeded the threshold. However, once the threshold was reached, further increases in thickness no longer resulted in more or larger DCs. This study also found that our sample of H. neanderthalensis and H. sapiens have different distribution patterns in thin areas, which may affect how their DCs connect with different branches of the middle meningeal vessels. This preliminary study provides evidence for the discussion on the interaction between the cranium, brain, and blood vessels. Future research should include more hominin fossils to better document the variation within each species and possible evolutionary trends among hominin lineages.

A new Late Miocene Hystrix (Hystricidae, Rodentia) from Turkey

The Çorakyerler fossil locality in Anatolia reveals unique faunal elements. This study introduces Hystrix kayae sp. nov., a new Late Miocene porcupine initially classified as Hystrix sp. Yavuz et al., 2018. This finding expands our knowledge of Late Miocene Anatolian porcupines, bringing the total number of known species to three. H. kayae sp. nov. is larger than Hystrix aryanensis and exhibits greater upper cheek tooth crown height. Its cheek tooth morphology differs from Hystrix depereti, and it possesses distinctive U-shaped choanae unlike Hystrix primigenia. The Çorakyerler locality may predate sites with H. aryanensis and H. primigenia but aligns temporally with Hystrix parvae localities. This study enhances our understanding of Late Miocene porcupine diversity in Anatolia, emphasizing the importance of Çorakyerler in unraveling the evolutionary history of these fascinating mammals.

Exceptionally preserved shark fossils from Mexico elucidate the long-standing enigma of the Cretaceous elasmobranch Ptychodus

The fossil fish Ptychodus Agassiz, 1834, characterized by a highly distinctive grinding dentition and an estimated gigantic body size (up to around 10 m), has remained one of the most enigmatic extinct elasmobranchs (i.e. sharks, skates and rays) for nearly two centuries. This widespread Cretaceous taxon is common in Albian to Campanian deposits from almost all continents. However, specimens mostly consist of isolated teeth or more or less complete dentitions, whereas cranial and post-cranial skeletal elements are very rare. Here we describe newly discovered material from the early Late Cretaceous of Mexico, including complete articulated specimens with preserved body outline, which reveals crucial information on the anatomy and systematic position of Ptychodus. Our phylogenetic and ecomorphological analyses indicate that ptychodontids were high-speed (tachypelagic) durophagous lamniforms (mackerel sharks), which occupied a specialized predatory niche previously unknown in fossil and extant elasmobranchs. Our results support the view that lamniforms were ecomorphologically highly diverse and represented the dominant group of sharks in Cretaceous marine ecosystems. Ptychodus may have fed predominantly on nektonic hard-shelled prey items such as ammonites and sea turtles rather than on benthic invertebrates, and its extinction during the Campanian, well before the end-Cretaceous crisis, might have been related to competition with emerging blunt-toothed globidensine and prognathodontine mosasaurs.

Cranial anatomy of Emeroleter levis and the phylogeny of Nycteroleteridae

Among the diverse basal reptile clade Parareptilia, the nycteroleters are among the most poorly understood. The interrelationships of nycteroleters are contentious, being recovered as both monophyletic and paraphyletic in different analyses, yet their anatomy has received little attention. We utilized x-ray computed tomography to investigate the skull of the nycteroleterid Emeroleter levis, revealing aspects of both the external and internal cranial anatomy that were previously unknown or undescribed, especially relating to the palate, braincase, and mandible. Our results reveal a greater diversity in nycteroleter cranial anatomy than was previously recognized, including variation in the contribution of the palatal elements to the orbitonasal ridge among nycteroleters. Of particular note are the unique dentition patterns in Emeroleter, including the presence of dentition on the ectopterygoid, an element which is typically edentulous in most parareptiles. We then incorporate the novel information gained from the computed tomography analysis into an updated phylogenetic analysis of parareptiles, producing a fully resolved Nycteroleteridae and further supporting previous suggestions that the genus 'Bashkyroleter' is paraphyletic.

Unveiling the ventral morphology of a rare early Cambrian great appendage arthropod from the Chengjiang biota of China

BACKGROUND

The early Cambrian arthropod clade Megacheira, also referred to as great appendage arthropods, comprised a group of diminutive and elongated predators during the early Palaeozoic era, around 518 million years ago. In addition to those identified in the mid-Cambrian Burgess Shale biota, numerous species are documented in the renowned 518-million-year-old Chengjiang biota of South China. Notably, one species, Tanglangia longicaudata, has remained inadequately understood due to limited available material and technological constraints. In this study, we, for the first time, examined eight fossil specimens (six individuals) utilizing state-of-the-art μCT and computer-based 3D rendering techniques to unveil the hitherto hidden ventral and appendicular morphology of this species.

RESULTS

We have identified a set of slender endopodites gradually narrowing distally, along with a leaf-shaped exopodite adorned with fringed setae along its margins, and a small putative exite attached to the basipodite. Our techniques have further revealed the presence of four pairs of biramous appendages in the head, aligning with the recently reported six-segmented head in other early euarthropods. Additionally, we have discerned two peduncle elements for the great appendage. These findings underscore that, despite the morphological diversity observed in early euarthropods, there exists similarity in appendicular morphology across various groups. In addition, we critically examine the existing literature on this taxon, disentangling previous mislabelings, mentions, descriptions, and, most importantly, illustrations.

CONCLUSIONS

The μCT-based investigation of fossil material of Tanglangia longicaudata, a distinctive early Cambrian euarthropod from the renowned Chengjiang biota, enhances our comprehensive understanding of the evolutionary morphology of the Megacheira. Its overall morphological features, including large cup-shaped eyes, raptorial great appendages, and a remarkably elongated telson, suggest its potential ecological role as a crepuscular predator and adept swimmer in turbid waters.

The oldest mysticete in the Northern Hemisphere

Extant baleen whales (Mysticeti) uniquely use keratinous baleen for filter-feeding and lack dentition, but the fossil record clearly shows that "toothed" baleen whales first appeared in the Late Eocene.1 Globally, only two Eocene mysticetes have been found, and both are from the Southern Hemisphere: Mystacodon selenensis from Peru, 36.4 mega-annum (Ma) ago1,2 and Llanocetus denticrenatus from Antarctica, 34.2 Ma ago.3,4 Based on a partial skull from the lower part of the Lincoln Creek Formation in Washington State, USA, we describe the Northern Hemisphere's geochronologically earliest mysticete, Fucaia humilis sp. nov. Geology, biostratigraphy, and magnetostratigraphy places Fucaia humilis sp. nov. in the latest Eocene (ca. 34.5 Ma ago, near the Eocene/Oligocene transition at 33.9 Ma ago), approximately coeval with the oldest record of fossil kelps, also in the northeastern Pacific.5 This observation leads to our hypothesis that the origin and development of a relatively stable, nutrient-rich kelp ecosystem5,6 in the latest Eocene may have fostered the radiation of small-sized toothed mysticetes (Family Aetiocetidae) in the North Pacific basin, a stark contrast to the larger Llanocetidae (whether Mystacodon belongs to llanocetids or another independent clade remains unresolved) with the latest Eocene onset of the Antarctic Circumpolar Current in the Southern Hemisphere.7,8,9 Our discovery suggests that disparate mechanisms and ecological scenarios may have nurtured contrasting early mysticete evolutionary histories in the Northern and Southern hemispheres.

New Canadian amber deposit fills gap in fossil record near end-Cretaceous mass extinction

Amber preserves an exceptional record of tiny, soft-bodied organisms and chemical environmental signatures, elucidating the evolution of arthropod lineages and the diversity, ecology, and biogeochemistry of ancient ecosystems. However, globally, fossiliferous amber deposits are rare in the latest Cretaceous and surrounding the Cretaceous-Paleogene (K-Pg) mass extinction.1,2,3,4,5 This faunal gap limits our understanding of arthropod diversity and survival across the extinction boundary.2,6 Contrasting hypotheses propose that arthropods were either relatively unaffected by the K-Pg extinction or experienced a steady decline in diversity before the extinction event followed by rapid diversification in the Cenozoic.2,6 These hypotheses are primarily based on arthropod feeding traces on fossil leaves and time-calibrated molecular phylogenies, not direct observation of the fossil record.2,7 Here, we report a diverse amber assemblage from the Late Cretaceous (67.04 ± 0.16 Ma) of the Big Muddy Badlands, Canada. The new deposit fills a critical 16-million-year gap in the arthropod fossil record spanning the K-Pg mass extinction. Seven arthropod orders and at least 11 insect families have been recovered, making the Big Muddy amber deposit the most diverse arthropod assemblage near the K-Pg extinction. Amber chemistry and stable isotopes suggest the amber was produced by coniferous (Cupressaceae) trees in a subtropical swamp near remnants of the Western Interior Seaway. The unexpected abundance of ants from extant families and the virtual absence of arthropods from common, exclusively Cretaceous families suggests that Big Muddy amber may represent a yet unsampled Late Cretaceous environment and provides evidence of a faunal transition before the end of the Cretaceous.

Prolonged faunal turnover in earliest ants revealed by North American Cretaceous amber

All ∼14,000 extant ant species descended from the same common ancestor, which lived ∼140-120 million years ago (Ma).1,2 While modern ants began to diversify in the Cretaceous, recent fossil evidence has demonstrated that older lineages concomitantly occupied the same ancient ecosystems.3 These early-diverging ant lineages, or stem ants, left no modern descendants; however, they dominated the fossil record throughout the Cretaceous until their ultimate extinction sometime around the K-Pg boundary. Even as stem ant lineages appear to be diverse and abundant throughout the Cretaceous, the extent of their longevity in the fossil record and circumstances contributing to their extinction remain unknown.3 Here we report the youngest stem ants, preserved in ∼77 Ma Cretaceous amber from North Carolina, which illustrate unexpected morphological stability and lineage persistence in this enigmatic group, rivaling the longevity of contemporary ants. Through phylogenetic reconstruction and morphometric analyses, we find evidence that total taxic turnover in ants was not accompanied by a fundamental morphological shift, in contrast to other analogous stem extinctions such as theropod dinosaurs. While stem taxa showed broad morphological variation, high-density ant morphospace remained relatively constant through the last 100 million years, detailing a parallel, but temporally staggered, evolutionary history of modern and stem ants.

Earliest known ophiuroids from high palaeolatitude, southern Gondwana, recovered from the Pragian to earliest Emsian Baviaanskloof Formation (Table Mountain Group, Cape Supergroup) South Africa

For the first time, ophiuroids have been found in South African strata predating the lowermost Bokkeveld Group. These comprise natural moulds and casts from two localities in the 'upper unit' of the Baviaanskloof Formation (Table Mountain Group). As a Pragian to earliest Emsian age has been inferred for this member, the new taxa comprise the earliest high-palaeolatitude ophiuroid records from southern Gondwana. Morphological analysis of the specimens revealed the presence of two distinct taxa. One is here described as Krommaster spinosus gen. et sp. nov., a new encrinasterid characterised by very large spines on the dorsal side of the disc, the ventral interradial marginal plates and the arm midlines. The second taxon is a poorly preserved specimen of Hexuraster weitzi, a cheiropterasterid previously described from the slightly younger Bokkeveld Group.

High phenotypic plasticity at the dawn of the eosauropterygian radiation

The initial radiation of Eosauropterygia during the Triassic biotic recovery represents a key event in the dominance of reptiles secondarily adapted to marine environments. Recent studies on Mesozoic marine reptile disparity highlighted that eosauropterygians had their greatest morphological diversity during the Middle Triassic, with the co-occurrence of Pachypleurosauroidea, Nothosauroidea and Pistosauroidea, mostly along the margins of the Tethys Ocean. However, these previous studies quantitatively analysed the disparity of Eosauropterygia as a whole without focussing on Triassic taxa, thus limiting our understanding of their diversification and morphospace occupation during the Middle Triassic. Our multivariate morphometric analyses highlight a clearly distinct colonization of the ecomorphospace by the three clades, with no evidence of whole-body convergent evolution with the exception of the peculiar pistosauroid Wangosaurus brevirostris, which appears phenotypically much more similar to nothosauroids. This global pattern is mostly driven by craniodental differences and inferred feeding specializations. We also reveal noticeable regional differences among nothosauroids and pachypleurosauroids of which the latter likely experienced a remarkable diversification in the eastern Tethys during the Pelsonian. Our results demonstrate that the high phenotypic plasticity characterizing the evolution of the pelagic plesiosaurians was already present in their Triassic ancestors, casting eosauropterygians as particularly adaptable animals.

Description and phylogenetic relationships of a new species of Torvoneustes (Crocodylomorpha, Thalattosuchia) from the Kimmeridgian of Switzerland

Metriorhynchids are marine crocodylomorphs found across Jurassic and Lower Cretaceous deposits of Europe and Central and South America. Despite being one of the oldest fossil families named in paleontology, the phylogenetic relationships within Metriorhynchidae have been subject to many revisions over the past 15 years. Herein, we describe a new metriorhynchid from the Kimmeridgian of Porrentruy, Switzerland. The material consists of a relatively complete, disarticulated skeleton preserving pieces of the skull, including the frontal, prefrontals, right postorbital, nasals, maxillae, right premaxillae and nearly the entire mandible, and many remains of the axial and appendicular skeleton such as cervical, dorsal, and caudal vertebrae, ribs, the left ischium, the right femur, and the right fibula. This new specimen is referred to the new species Torvoneustes jurensis sp. nov. as part of the large-bodied macrophagous tribe Geosaurini. Torvoneustes jurensis presents a unique combination of cranial and dental characters including a smooth cranium, a unique frontal shape, acute ziphodont teeth, an enamel ornamentation made of numerous apicobasal ridges shifting to small ridges forming an anastomosed pattern toward the apex of the crown and an enamel ornamentation touching the carina. The description of this new species allows to take a new look at the currently proposed evolutionary trends within the genus Torvoneustes and provides new information on the evolution of this clade.

A new species of the genus Burmadactylus Heads, 2009 from mid-Cretaceous amber in north Myanmar (Orthoptera: Caelifera: Tridactyloidea)

This paper describes a new species of the genus Burmadactylus Heads, 2009 (Tridactylidae: Dentridactylinae) from Burmese amber, namely: Burmadactylus tenuicerci sp. nov. This new species is similar to Burmadactylus grimaldi Heads, 2009, but differs from latter by mesotibia basally inflated and almost as long as mesofemur; the second segment of cercus distinctly slender; paraproctal lobe covered with sparse and slender setae, one of the setae near the apex distinct thick and long.

New heterodont odontocetes from the Oligocene Pysht Formation in Washington State, U.S.A., and a reevaluation of Simocetidae (Cetacea, Odontoceti)

Odontocetes first appeared in the fossil record by the early Oligocene, and their early evolutionary history can provide clues as to how some of their unique adaptations, such as echolocation, evolved. Here, three new specimens from the early to late Oligocene Pysht Formation are described further increasing our understanding of the richness and diversity of early odontocetes, particularly for the North Pacific. Phylogenetic analysis shows that the new specimens are part of a more inclusive, redefined Simocetidae, which now includes Simocetus rayi, Olympicetus sp. 1, Olympicetus avitus, O. thalassodon sp. nov., and a large unnamed taxon (Simocetidae gen. et sp. A), all part of a North Pacific clade that represents one of the earliest diverging groups of odontocetes. Amongst these, Olympicetus thalassodon sp. nov. represents one of the best known simocetids, offering new information on the cranial and dental morphology of early odontocetes. Furthermore, the inclusion of CCNHM 1000, here considered to represent a neonate of Olympicetus sp., as part of the Simocetidae, suggests that members of this group may not have had the capability of ultrasonic hearing, at least during their early ontogenetic stages. Based on the new specimens, the dentition of simocetids is interpreted as being plesiomorphic, with a tooth count more akin to that of basilosaurids and early toothed mysticetes, while other features of the skull and hyoid suggest various forms of prey acquisition, including raptorial or combined feeding in Olympicetus spp., and suction feeding in Simocetus. Finally, body size estimates show that small to moderately large taxa are present in Simocetidae, with the largest taxon represented by Simocetidae gen. et sp. A with an estimated body length of 3 m, which places it as the largest known simocetid, and amongst the largest Oligocene odontocetes. The new specimens described here add to a growing list of Oligocene marine tetrapods from the North Pacific, further promoting faunistic comparisons across other contemporaneous and younger assemblages, that will allow for an improved understanding of the evolution of marine faunas in the region.

Miniaturization during a Silurian environmental crisis generated the modern brittle star body plan

Pivotal anatomical innovations often seem to appear by chance when viewed through the lens of the fossil record. As a consequence, specific driving forces behind the origination of major organismal clades generally remain speculative. Here, we present a rare exception to this axiom by constraining the appearance of a diverse animal group (the living Ophiuroidea) to a single speciation event rather than hypothetical ancestors. Fossils belonging to a new pair of temporally consecutive species of brittle stars (Ophiopetagno paicei gen. et sp. nov. and Muldaster haakei gen. et sp. nov.) from the Silurian (444-419 Mya) of Sweden reveal a process of miniaturization that temporally coincides with a global extinction and environmental perturbation known as the Mulde Event. The reduction in size from O. paicei to M. haakei forced a structural simplification of the ophiuroid skeleton through ontogenetic retention of juvenile traits, thereby generating the modern brittle star bauplan.

Ovipositor and mouthparts in a fossil insect support a novel ecological role for early orthopterans in 300 million years old forests

A high portion of the earliest known insect fauna is composed of the so-called 'lobeattid insects', whose systematic affinities and role as foliage feeders remain debated. We investigated hundreds of samples of a new lobeattid species from the Xiaheyan locality using a combination of photographic techniques, including reflectance transforming imaging, geometric morphometrics, and biomechanics to document its morphology, and infer its phylogenetic position and ecological role. Ctenoptilus frequens sp. nov. possessed a sword-shaped ovipositor with valves interlocked by two ball-and-socket mechanisms, lacked jumping hind-legs, and certain wing venation features. This combination of characters unambiguously supports lobeattids as stem relatives of all living Orthoptera (crickets, grasshoppers, katydids). Given the herein presented and other remains, it follows that this group experienced an early diversification and, additionally, occurred in high individual numbers. The ovipositor shape indicates that ground was the preferred substrate for eggs. Visible mouthparts made it possible to assess the efficiency of the mandibular food uptake system in comparison to a wide array of extant species. The new species was likely omnivorous which explains the paucity of external damage on contemporaneous plant foliage.

Living fast in the Triassic: New data on life history in Lystrosaurus (Therapsida: Dicynodontia) from northeastern Pangea

Lystrosaurus was one of the few tetrapods to survive the Permo-Triassic mass extinction, the most profound biotic crisis in Earth’s history. The wide paleolatitudinal range and high abundance of Lystrosaurus during the Early Triassic provide a unique opportunity to investigate changes in growth dynamics and longevity following the mass extinction, yet most studies have focused only on species that lived in the southern hemisphere. Here, we present the long bone histology from twenty Lystrosaurus skeletal elements spanning a range of sizes that were collected in the Jiucaiyuan Formation of northwestern China. In addition, we compare the average body size of northern and southern Pangean Triassic-aged species and conduct cranial geometric morphometric analyses of southern and northern taxa to begin investigating whether specimens from China are likely to be taxonomically distinct from South African specimens. We demonstrate that Lystrosaurus from China have larger average body sizes than their southern Pangean relatives and that their cranial morphologies are distinctive. The osteohistological examination revealed sustained, rapid osteogenesis punctuated by growth marks in some, but not all, immature individuals from China. We find that the osteohistology of Chinese Lystrosaurus shares a similar growth pattern with South African species that show sustained growth until death. However, bone growth arrests more frequently in the Chinese sample. Nevertheless, none of the long bones sampled here indicate that maximum or asymptotic size was reached, suggesting that the maximum size of Lystrosaurus from the Jiucaiyuan Formation remains unknown.

Postcranial osteology of Beipiaosaurus inexpectus (Theropoda: Therizinosauria)

Beipiaosaurus inexpectus, from the Lower Cretaceous Yixian Formation (Sihetun locality, near Beipiao), Liaoning, China, is a key taxon for understanding the early evolution of therizinosaurians. Since initial publication in 1999, only the cranial elements of this taxon have been described in detail. Here we present a detailed description of the postcranial skeletal anatomy of the holotype specimen of B. inexpectus, including two never before described dorsal vertebrae from the anterior half of the series. Based on these observations, and comparisons with the postcranial skeleton of therizinosaurian taxa named since the most recent diagnosis, we revised the diagnostic features for B. inexpectus adding three new possible autapomorphies (PII-3 shorter than PIII-4, subequal length of the pre- and postacetabular portions of the ilium, and equidimensional pubic peduncle of ilium). Additionally, we also propose three possible synapomorphies for more inclusive taxa (Therizinosauroidea and Therizinosauridae) and discuss implications for evolutionary trends within Therizinosauria. The newly acquired data from the postcranial osteology of the holotype specimen of B. inexpectus sheds light on our understanding of postcranial skeletal evolution and identification of therizinosaurians.

The pattern of brain-size change in the early evolution of cetaceans

Most authors have identified two rapid increases in relative brain size (encephalization quotient, EQ) in cetacean evolution: first at the origin of the modern suborders (odontocetes and mysticetes) around the Eocene-Oligocene transition, and a second at the origin of the delphinoid odontocetes during the middle Miocene. We explore how methods used to estimate brain and body mass alter this perceived timing and rate of cetacean EQ evolution. We provide new data on modern mammals (mysticetes, odontocetes, and terrestrial artiodactyls) and show that brain mass and endocranial volume scale allometrically, and that endocranial volume is not a direct proxy for brain mass. We demonstrate that inconsistencies in the methods used to estimate body size across the Eocene-Oligocene boundary have caused a spurious pattern in earlier relative brain size studies. Instead, we employ a single method, using occipital condyle width as a skeletal proxy for body mass using a new dataset of extant cetaceans, to clarify this pattern. We suggest that cetacean relative brain size is most accurately portrayed using EQs based on the scaling coefficients as observed in the closely related terrestrial artiodactyls. Finally, we include additional data for an Eocene whale, raising the sample size of Eocene archaeocetes to seven. Our analysis of fossil cetacean EQ is different from previous works which had shown that a sudden increase in EQ coincided with the origin of odontocetes at the Eocene-Oligocene boundary. Instead, our data show that brain size increased at the origin of basilosaurids, 5 million years before the Eocene-Oligocene transition, and we do not observe a significant increase in relative brain size at the origin of odontocetes.

A Late Cretaceous dinosaur and crocodyliform faunal association-based on isolate teeth and osteoderms-at Cerro Fortaleza Formation (Campanian-Maastrichtian) type locality, Santa Cruz, Argentina

The Late Cretaceous dinosaur record in southern South America has been improved recently; particularly with findings from Chorrillo and Cerro Fortaleza formations, both bearing ankylosaur remains, a clade that was not previously recorded in the Austral Basin. The dinosaur fauna of the type locality of Cerro Fortaleza Formation is known from -and biased to- large-sized sauropod remains and a single described taxon, the titanosaur Dreadnoughtus schrani. Here, we report the taxonomic composition of a site preserving thirteen isolated teeth and several osteoderms belonging to three dinosaur clades (Abelisauridae, Titanosauria, and Nodosauridae), and at least one clade of notosuchian crocodyliforms (Peirosauridae). They come from sediments positioned at the mid-section of the Cerro Fortaleza Formation, which is Campanian-Maastrichtian in age, adding valuable information to the abundance and biodiversity of this Cretaceous ecosystem. Since non-titanosaur dinosaur bones are almost absent in the locality, the teeth presented here provide a window onto the archosaur biodiversity of the Late Cretaceous in southern Patagonia. The nodosaurid tooth and small armor ossicles represent the first record of ankylosaurs for this stratigraphic unit. The peirosaurid material also represents the most austral record of the clade in South America.

The discovery of an in situ Neanderthal remain in the Bawa Yawan Rockshelter, West-Central Zagros Mountains, Kermanshah

Neanderthal extinction has been a matter of debate for many years. New discoveries, better chronologies and genomic evidence have done much to clarify some of the issues. This evidence suggests that Neanderthals became extinct around 40,000–37,000 years before present (BP), after a period of coexistence with Homo sapiens of several millennia, involving biological and cultural interactions between the two groups. However, the bulk of this evidence relates to Western Eurasia, and recent work in Central Asia and Siberia has shown that there is considerable local variation. Southwestern Asia, despite having a number of significant Neanderthal remains, has not played a major part in the debate over extinction. Here we report a Neanderthal deciduous canine from the site of Bawa Yawan in the West-Central Zagros Mountains of Iran. The tooth is associated with Zagros Mousterian lithics, and its context is preliminary dated to between ~43,600 and ~41,500 years ago.

The cranial anatomy and relationships of Cardiocorax mukulu (Plesiosauria: Elasmosauridae) from Bentiaba, Angola

We report a new specimen of the plesiosaur Cardiocorax mukulu that includes the most complete plesiosaur skull from sub-Saharan Africa. The well-preserved three-dimensional nature of the skull offers rare insight into the cranial anatomy of elasmosaurid plesiosaurians. The new specimen of Cardiocorax mukulu was recovered from Bentiaba, Namibe Province in Angola, approximately three meters above the holotype. The new specimen also includes an atlas-axis complex, seventeen postaxial cervical vertebrae, partial ribs, a femur, and limb elements. It is identified as Cardiocorax mukulu based on an apomorphy shared with the holotype where the cervical neural spine is approximately as long anteroposteriorly as the centrum and exhibits a sinusoidal anterior margin. The new specimen is nearly identical to the holotype and previously referred material in all other aspects. Cardiocorax mukulu is returned in an early-branching or intermediate position in Elasmosauridae in four out of the six of our phylogenetic analyses. Cardiocorax mukulu lacks the elongated cervical vertebrae that is characteristic of the extremely long-necked elasmosaurines, and the broad skull with and a high number of maxillary teeth (28-40) which is characteristic of Aristonectinae. Currently, the most parsimonious explanation concerning elasmosaurid evolutionary relationships, is that Cardiocorax mukulu represents an older lineage of elasmosaurids in the Maastrichtian.

Early Pleistocene faunivorous hominins were not kleptoparasitic, and this impacted the evolution of human anatomy and socio-ecology

Humans are unique in their diet, physiology and socio-reproductive behavior compared to other primates. They are also unique in the ubiquitous adaptation to all biomes and habitats. From an evolutionary perspective, these trends seem to have started about two million years ago, coinciding with the emergence of encephalization, the reduction of the dental apparatus, the adoption of a fully terrestrial lifestyle, resulting in the emergence of the modern anatomical bauplan, the focalization of certain activities in the landscape, the use of stone tools, and the exit from Africa. It is in this period that clear taphonomic evidence of a switch in diet with respect to Pliocene hominins occurred, with the adoption of carnivory. Until now, the degree of carnivorism in early humans remained controversial. A persistent hypothesis is that hominins acquired meat irregularly (potentially as fallback food) and opportunistically through klepto-foraging. Here, we test this hypothesis and show, in contrast, that the butchery practices of early Pleistocene hominins (unveiled through systematic study of the patterning and intensity of cut marks on their prey) could not have resulted from having frequent secondary access to carcasses. We provide evidence of hominin primary access to animal resources and emphasize the role that meat played in their diets, their ecology and their anatomical evolution, ultimately resulting in the ecologically unrestricted terrestrial adaptation of our species. This has major implications to the evolution of human physiology and potentially for the evolution of the human brain.

Tooth morphology elucidates shark evolution across the end-Cretaceous mass extinction

Sharks (Selachimorpha) are iconic marine predators that have survived multiple mass extinctions over geologic time. Their prolific fossil record is represented mainly by isolated shed teeth, which provide the basis for reconstructing deep time diversity changes affecting different selachimorph clades. By contrast, corresponding shifts in shark ecology, as measured through morphological disparity, have received comparatively limited analytical attention. Here, we use a geometric morphometric approach to comprehensively examine tooth morphologies in multiple shark lineages traversing the catastrophic end-Cretaceous mass extinction-this event terminated the Mesozoic Era 66 million years ago. Our results show that selachimorphs maintained virtually static levels of dental disparity in most of their constituent clades across the Cretaceous-Paleogene interval. Nevertheless, selective extinctions did impact apex predator species characterized by triangular blade-like teeth. This is particularly evident among lamniforms, which included the dominant Cretaceous anacoracids. Conversely, other groups, such as carcharhiniforms and orectolobiforms, experienced disparity modifications, while heterodontiforms, hexanchiforms, squaliforms, squatiniforms, and †synechodontiforms were not overtly affected. Finally, while some lamniform lineages disappeared, others underwent postextinction disparity increases, especially odontaspidids, which are typified by narrow-cusped teeth adapted for feeding on fishes. Notably, this increase coincides with the early Paleogene radiation of teleosts as a possible prey source, and the geographic relocation of disparity sampling "hotspots," perhaps indicating a regionally disjunct extinction recovery. Ultimately, our study reveals a complex morphological response to the end-Cretaceous mass extinction and highlights an event that influenced the evolution of modern sharks.

Different environmental variables predict body and brain size evolution in Homo

Increasing body and brain size constitutes a key macro-evolutionary pattern in the hominin lineage, yet the mechanisms behind these changes remain debated. Hypothesized drivers include environmental, demographic, social, dietary, and technological factors. Here we test the influence of environmental factors on the evolution of body and brain size in the genus Homo over the last one million years using a large fossil dataset combined with global paleoclimatic reconstructions and formalized hypotheses tested in a quantitative statistical framework. We identify temperature as a major predictor of body size variation within Homo, in accordance with Bergmann's rule. In contrast, net primary productivity of environments and long-term variability in precipitation correlate with brain size but explain low amounts of the observed variation. These associations are likely due to an indirect environmental influence on cognitive abilities and extinction probabilities. Most environmental factors that we test do not correspond with body and brain size evolution, pointing towards complex scenarios which underlie the evolution of key biological characteristics in later Homo.

A new styracosternan hadrosauroid (Dinosauria: Ornithischia) from the Early Cretaceous of Portell, Spain

A new styracosternan ornithopod genus and species is described based on the right dentary of a single specimen from the Mirambell Formation (Early Cretaceous, early Barremian) at the locality of Portell, (Castellón, Spain). Portellsaurus sosbaynati gen. et sp. nov. is diagnosed by two autapomorphic features as well as a unique combination of characters. The autapomorphies include: the absence of a bulge along the ventral margin directly ventral to the base of the coronoid process and the presence of a deep oval cavity on the medial surface of the mandibular adductor fossa below the eleventh-twelfth tooth position. Phylogenetic analyses reveal that the new Iberian form is more closely related to the African taxon Ouranosaurus nigeriensis than to its synchronic Iberian taxa Magnamanus soriaensis and Iguanodon galvensis. In addition, Portellsaurus sosbaynati is less related to other Iberian taxa such as Iguanodon bernissartensis and Proa valdearinnoensis than to the other Early Cretaceous Iberian styracosternans Mantellisaurus atherfieldensis and Morelladon beltrani. A new phylogenetic hypothesis is proposed that resolves Iguanodon (I. bernissartensis, I. galvensis) with the Valanginian Barilium dawsoni into a monophyletic clade (Iguanodontoidea). The recognition of Portellsaurus sosbaynati gen. et sp. nov. as the first styracosternan dinosaur species identified from the Margas de Mirambell Formation (early Barremian-early late Barremian) in the Morella sub-basin (Maestrat Basin, eastern Spain) indicates that the Iberian Peninsula was home to a highly diverse assemblage of medium-to-large bodied styracosternan hadrosauriforms during the Early Cretaceous.

A remarkable group of thick-headed Triassic Period archosauromorphs with a wide, possibly Pangean distribution

The radiation of archosauromorph reptiles in the Triassic Period produced an unprecedented collection of diverse and disparate forms with a mix of varied ecologies and body sizes. Some of these forms were completely unique to the Triassic, whereas others were converged on by later members of Archosauromorpha. One of the most striking examples of this is with Triopticus primus, the early dome-headed form later mimicked by pachycephalosaurid dinosaurs. Here we fully describe the cranial anatomy of Triopticus primus, but also recognize a second dome-headed form from a Upper Triassic deposit in present-day India. The new taxon, Kranosaura kuttyi gen. et sp. nov., is likely the sister taxon of Triopticus primus based on the presence of a greatly expanded skull roof with a deep dorsal opening (possibly the pineal opening) through the dome, similar cranial sculpturing, and a skull table that is expanded more posterior than the posterior extent of the basioccipital. However, the dome of Kranosaura kuttyi gen. et sp. nov. extends anterodorsally, unlike that of any other archosauromorph. Histological sections and computed tomographic reconstructions through the skull of Kranosaura kuttyi gen. et sp. nov. further reveal the uniqueness of the dome of these early archosauromorphs. Moreover, our integrated analysis further demonstrates that there are many ways to create a dome in Amniota. The presence of 'dome-headed' archosauromorphs at two localities on the western and eastern portions of Pangea suggests that these archosauromorphs were widespread and are likely part of more assemblages than currently recognized.

An Oligocene giant rhino provides insights into Paraceratherium evolution

As one of the largest land mammals, the origin and evolution of the giant rhino Paraceratherium bugtiense in Pakistan have been unclear. We report a new species Paraceratherium linxiaense sp. nov. from northwestern China with an age of 26.5 Ma. Morphology and phylogeny reveal that P. linxiaense is the highly derived species of the genus Paraceratherium, and its clade with P. lepidum has a tight relationship to P. bugtiense. Based on the paleogeographical literature, P. bugtiense represents a range expansion of Paraceratherium from Central Asia via the Tibetan region. By the late Oligocene, P. lepidum and P. linxiaense were found in the north side of the Tibetan Plateau. The Tibetan region likely hosted some areas with low elevation, possibly under 2000 m during Oligocene, and the lineage of giant rhinos could have dispersed freely along the eastern coast of the Tethys Ocean and perhaps through some lowlands of this region.

Two turtles with soft tissue preservation from the platy limestones of Germany provide evidence for marine flipper adaptations in Late Jurassic thalassochelydians

Late Jurassic deposits across Europe have yielded a rich fauna of extinct turtles. Although many of these turtles are recovered from marine deposits, it is unclear which of these taxa are habitually marine and which may be riverine species washed into nearby basins, as adaptations to open marine conditions are yet to be found. Two new fossils from the Late Jurassic of Germany provide unusually strong evidence for open marine adaptations. The first specimen is a partial shell and articulated hind limb from the Late Jurassic (early Tithonian) platy limestones of Schernfeld near Eichstätt, which preserves the integument of the hind limb as an imprint. The skin is fully covered by flat, polygonal scales, which stiffen the pes into a paddle. Although taxonomic attribution is not possible, similarities are apparent with Thalassemys. The second specimen is a large, articulated skeleton with hypertrophied limbs referable to Thalassemys bruntrutana from the Late Jurassic (early Late Kimmeridgian) platy limestone of Wattendorf, near Bamberg. Even though the skin is preserved as a phosphatic film, the scales are not preserved. This specimen can nevertheless be inferred to have had paddles stiffened by scales based on the pose in which they are preserved, the presence of epibionts between the digits, and by full morphological correspondence to the specimen from Schernfeld. An analysis of scalation in extant turtles demonstrated that elongate flippers stiffed by scales are a marine adaptation, in contrast to the elongate but flexible flippers of riverine turtles. Phylogenetic analysis suggests that Thalassemys bruntrutana is referable to the mostly Late Jurassic turtle clade Thalassochelydia. The marine adapted flippers of this taxon therefore evolved convergently with those of later clades of marine turtles. Although thalassochelydian fossils are restricted to Europe, with one notable exception from Argentina, their open marine adaptations combined with the interconnectivity of Jurassic oceans predict that the clade must have been even more wide-spread during that time.

An early bothremydid from the Arlington Archosaur Site of Texas

Four turtle taxa are previously documented from the Cenomanian Arlington Archosaur Site (AAS) of the Lewisville Formation (Woodbine Group) in Texas. Herein, we describe a new side-necked turtle (Pleurodira), Pleurochayah appalachius gen. et sp. nov., which is a basal member of the Bothremydidae. Pleurochayah appalachius gen. et sp. nov. shares synapomorphic characters with other bothremydids, including shared traits with Kurmademydini and Cearachelyini, but has a unique combination of skull and shell traits. The new taxon is significant because it is the oldest crown pleurodiran turtle from North America and Laurasia, predating bothremynines Algorachelus peregrinus and Paiutemys tibert from Europe and North America respectively. This discovery also documents the oldest evidence of dispersal of crown Pleurodira from Gondwana to Laurasia. Pleurochayah appalachius gen. et sp. nov. is compared to previously described fossil pleurodires, placed in a modified phylogenetic analysis of pelomedusoid turtles, and discussed in the context of pleurodiran distribution in the mid-Cretaceous. Its unique combination of characters demonstrates marine adaptation and dispersal capability among basal bothremydids.

Distinguishing African bovids using Zooarchaeology by Mass Spectrometry (ZooMS): New peptide markers and insights into Iron Age economies in Zambia

Assessing past foodways, subsistence strategies, and environments depends on the accurate identification of animals in the archaeological record. The high rates of fragmentation and often poor preservation of animal bones at many archaeological sites across sub-Saharan Africa have rendered archaeofaunal specimens unidentifiable beyond broad categories, such as “large mammal” or “medium bovid”. Identification of archaeofaunal specimens through Zooarchaeology by Mass Spectrometry (ZooMS), or peptide mass fingerprinting of bone collagen, offers an avenue for identification of morphologically ambiguous or unidentifiable bone fragments from such assemblages. However, application of ZooMS analysis has been hindered by a lack of complete reference peptide markers for African taxa, particularly bovids. Here we present the complete set of confirmed ZooMS peptide markers for members of all African bovid tribes. We also identify two novel peptide markers that can be used to further distinguish between bovid groups. We demonstrate that nearly all African bovid subfamilies are distinguishable using ZooMS methods, and some differences exist between tribes or sub-tribes, as is the case for Bovina (cattle) vs. Bubalina (African buffalo) within the subfamily Bovinae. We use ZooMS analysis to identify specimens from extremely fragmented faunal assemblages from six Late Holocene archaeological sites in Zambia. ZooMS-based identifications reveal greater taxonomic richness than analyses based solely on morphology, and these new identifications illuminate Iron Age subsistence economies c. 2200–500 cal BP. While the Iron Age in Zambia is associated with the transition from hunting and foraging to the development of farming and herding, our results demonstrate the continued reliance on wild bovids among Iron Age communities in central and southwestern Zambia Iron Age and herding focused primarily on cattle. We also outline further potential applications of ZooMS in African archaeology.

A derived dryolestid mammal indicates possible insular endemism in the Late Jurassic of Germany

The Langenberg Quarry near Bad Harzburg has yielded the first Jurassic stem therian mammal of Germany, recovered from Kimmeridgian (Late Jurassic) near shore deposits of a palaeo-island within the Lower Saxony Basin of the European archipelago. The new stem therian is represented by one lower and three upper molars. Hercynodon germanicus gen. et sp. nov. is attributed to the Dryolestidae, a group of pretribosphenic crown mammals that was common in western Laurasia from the Middle Jurassic to the Early Cretaceous. The new taxon is characterised by small size, a reduced cusp pattern in the upper molars lacking a metacone, and enhancement of the shearing crests paracrista and metacrista. Phylogenetic analysis identified Hercynodon gen. nov. as sister taxon of Crusafontia from the Lower Cretaceous (Barremian) of Spain. Both taxa belong to an endemic European clade of dryolestids, including also Achyrodon and Phascolestes from the earliest Cretaceous (Berriasian) of England. Despite its greater geological age, Hercynodon gen. nov. is the most derived representative of that clade, indicated by the complete reduction of the metacone. The discrepancy between derived morphology and geological age may be explained by an increased rate of character evolution in insular isolation. Other insular phenomena have earlier been observed in vertebrates from the Langenberg Quarry, such as dwarfism in the small sauropod Europasaurus, and possible gigantism in the morganucodontan mammaliaform Storchodon and the pinheirodontid multituberculate mammal Teutonodon which grew unusually large.

The impact of locomotion on the brain evolution of squirrels and close relatives

How do brain size and proportions relate to ecology and evolutionary history? Here, we use virtual endocasts from 38 extinct and extant rodent species spanning 50+ million years of evolution to assess the impact of locomotion, body mass, and phylogeny on the size of the brain, olfactory bulbs, petrosal lobules, and neocortex. We find that body mass and phylogeny are highly correlated with relative brain and brain component size, and that locomotion strongly influences brain, petrosal lobule, and neocortical sizes. Notably, species living in trees have greater relative overall brain, petrosal lobule, and neocortical sizes compared to other locomotor categories, especially fossorial taxa. Across millions of years of Eocene-Recent environmental change, arboreality played a major role in the early evolution of squirrels and closely related aplodontiids, promoting the expansion of the neocortex and petrosal lobules. Fossoriality in aplodontiids had an opposing effect by reducing the need for large brains.

Preliminary bone histological analysis of Lystrosaurus (Therapsida: Dicynodontia) from the Lower Triassic of North China, and its implication for lifestyle and environments after the end-Permian extinction

Lystrosaurus represents one of the most successful dicynodonts, a survivor of the end-Permian mass extinction that remained abundant in the Early Triassic, but many aspects of its paleobiology are still controversial. The bone histology of Lystrosaurus species from South Africa and India has provided important information on their growth strategy and lifestyle, but until recently no data was available on the bone histology of Lystrosaurus from China. Here, we report on the bone microstructure of seven Lystrosaurus individuals from the Lower Triassic of Xinjiang, providing the first such data for the Chinese Lystrosaurus species. Our samples indicate that the microstructure of Lystrosaurus limb bones from China is characterized by fibrolamellar bone tissue similar to those from South Africa and India. Three ontogenetic stages were identified: juvenile, early subadult, and late subadult based on lines of arrested growth (LAGs) and bone tissue changes. Bone histology supports a rapid growth strategy for Lystrosaurus during early ontogeny. Unlike Early Triassic Lystrosaurus from South Africa, lines of arrested growth are common in our specimens, suggesting that many individuals of Chinese Lystrosaurus had reached the subadult stage and were interrupted in growth. The differences in bone histology between Lystrosaurus from South Africa and China may indicate different environmental conditions in these two regions.

New data on Beurlenia araripensis Martins-Neto & Mezzalira, 1991, a lacustrine shrimp from Crato Formation, and its morphological variations based on the shape and the number of rostral spines

Fossil freshwater carideans are very rare worldwide. Here, we present new taxonomic remarks about Beurlenia araripensis from the Early Cretaceous laminated limestones of the Crato Formation, Araripe Basin, northeastern Brazil. We analyzed five fossil samples, testing the morphological variations such as, rostrum with 5 to 14 supra-rostral spines and 2 to 3 sub-rostral spines, which appears as serrate for Caridea. This variation demonstrates a morphologic plasticity also seen in extant species of the group, such as those of the genera Macrobrachium and Palaemon.

An overview on trilobite eyes and their functioning

Great progress has been made during the last decades in understanding visual systems of arthropods living today. Thus it seems worthwhile to review what is known about structure and function of the eyes of trilobites, the most important group of marine arthropods during the Paleozoic. There are three types of compound eyes in trilobites. The oldest and most abundant is the so-called holochroal eye. The sensory system represents a typical apposition eye, and all units are covered by one cornea in common. The so-called abathochroal eye (only in eodiscid trilobites) consists of small lenses, each individually covered by a thin cuticular cornea. The schizochroal eye is represented just in the suborder Phacopina, and probably is a highly specialized visual system. We discuss the calcitic character of trilobite lenses, the phylogenetic relevance of the existence of crystalline cones in trilobites, and consider adaptations of trilobite's compound eyes to different ecological constraints. The aim of this article is to give a resumé of what is known so far about trilobite vision, and to open perspectives to what still might be done.

First rebbachisaurid sauropod dinosaur from Asia

Dzharatitanis kingi gen. et sp. nov. is based on an isolated anterior caudal vertebra (USNM 538127) from the Upper Cretaceous (Turonian) Bissekty Formation at Dzharakuduk, Uzbekistan. Phylogenetic analysis places the new taxon within the diplodocoid clade Rebbachisauridae. This is the first rebbachisaurid reported from Asia and one of the youngest rebbachisaurids in the known fossil record. The caudal is characterized by a slightly opisthocoelous centrum, 'wing-like' transverse processes with large but shallow PRCDF and POCDF, and the absence of a hyposphenal ridge and of TPRL and TPOL. The neural spine has high SPRL, SPDL, SPOL, and POSL and is pneumatized. The apex of neural spine is transversely expanded and bears triangular lateral processes. The new taxon shares with Demandasaurus and the Wessex rebbachisaurid a high SPDL on the lateral side of the neural spine, separated from SPRL and SPOL. This possibly suggests derivation of Dzharatitanis from European rebbachisaurids. This is the second sauropod group identified in the assemblage of non-avian dinosaurs from the Bissekty Formation, in addition to a previously identified indeterminate titanosaurian.

The late Holocene demise of a sublittoral oyster bed in the North Sea

A fossil oyster bed (Ostrea edulis) was recently encountered offshore Helgoland (German Bight). Oysters are important filter feeders in marine environments and their habitat structure supports a large associated biodiversity. The European flat oyster Ostrea edulis has historically occurred in vast populations in the North Sea, but declined massively in the early 20th century. The ecological restoration of Ostrea habitats is a current focal point in the North Sea. To better understand the mechanisms that caused the local collapse of the oyster population, this study investigated the size structure, weight, and age of the shells, along with the spatial dimensions, seafloor properties, and environmental context of the oyster bed. The results show that the demise of the population occurred around 700 CE, ruling out excessive harvest as a driver of decline. Synchronicity of increased geomorphological activity of rivers and concurrent major land use changes in early medieval Europe suggest that increased sedimentation was a viable stressor that reduced the performance of the oysters. The shells provided no indication of a demographically poor state of the oyster bed prior to its demise, but manifested evidence of the wide-spread occurrence of the boring sponge Cliona sp. Our study challenges the assumption of a stable preindustrial state of the European flat oyster in the North Sea, and we conclude that the long-term variability of environmental conditions needs to be addressed to benchmark success criteria for the restoration of O. edulis.

Reassessment of the enigmatic ruminant Miocene genus Amphimoschus Bourgeois, 1873 (Mammalia, Artiodactyla, Pecora)

Amphimoschus is an extinct Eurasian ruminant genus, mostly recorded in Europe, without a close living relative and, hence, an unknown systematic position. This genus is known from around 50 localities from the late early to the middle Miocene. Two species were described during 180 years, but since their first description during the late 19^th century and early 20^th century, hardly any detailed taxonomic work has been done on the genus. Over the years, extensive collecting and excavating activities have enriched collections with more and more complete material of this still rare and enigmatic animal. Most interestingly, a number of skull remains have been unearthed and are promising in terms of providing phylogenetic information. In the present paper, we describe cranial material, the bony labyrinth, the dentition through 780 teeth and five skulls from different ontogenetic stages. We cannot find a clear morphometric distinction between the supposedly smaller and older species Amphimoschus artenensis and the supposedly younger and larger species A. ponteleviensis. Accordingly, we have no reason to retain the two species and propose, following the principle of priority (ICZN chapter 6 article 23), that only A. ponteleviensis Bourgeois, 1873 is valid. Our studies on the ontogenetic variation of Amphimoschus does reveal that the sagittal crest may increase in size and a supraorbital ridge may appear with age. Despite the abundant material, the family affiliation is still uncertain.

Giant Hyena Pachycrocuta brevirostris (Hyaenidae, Carnivora) from the Lower Pleistocene of Taurida Cave, Crimea

The dental remains of a giant hyena Pachycrocuta brevirostris (Gervais, 1850) from the Early Pleistocene locality of the Taurida cave (Crimea, Late Villafranchian, 1.8-1.5 Ma) are described. This species was a typical representative of the Villafranchian fauna of the Eastern Mediterranean. The Taurida cave was occasionally used by hyenas and other carnivorans as a den and retreat.

Tooth replacement patterns in the Early Triassic epicynodont Galesaurus planiceps (Therapsida, Cynodontia)

Sixteen specimens of the Early Triassic cynodont Galesaurus planiceps (including eight that were scanned using micro-computed tomography) representing different ontogenetic stages were assembled to study the dental replacement in the species. The growth series shows that the incisors and postcanines continue to develop and replace, even in the largest (presumably oldest) specimen. In contrast, replacement of the canines ceased with the attainment of skeletal maturity, at a basal skull length of ~90 mm, suggesting that Galesaurus had a finite number of canine replacement cycles. Additionally, the functional canine root morphology of these larger specimens showed a tendency to be open-rooted, a condition not previously reported in Mesozoic theriodonts. An alternating pattern of tooth replacement was documented in the maxillary and mandibular postcanine series. Both postcanine series increased in tooth number as the skull lengthened, with the mandibular postcanine series containing more teeth than the maxillary series. In the maxilla, the first postcanine is consistently the smallest tooth, showing a proportional reduction in size as skull length increased. The longer retention of a tooth in this first locus is a key difference between Galesaurus and Thrinaxodon, in which the mesial-most postcanines are lost after replacement. This difference has contributed to the lengthening of the postcanine series in Galesaurus, as teeth continued to be added to the distal end of the tooth row through ontogeny. Overall, there are considerable differences between Galesaurus and Thrinaxodon relating to the replacement and development of their teeth.

A new ophthalmosaurid ichthyosaur from the Upper Jurassic (Early Tithonian) Kimmeridge Clay of Dorset, UK, with implications for Late Jurassic ichthyosaur diversity

A new ophthalmosaurid ichthyosaur, Thalassodraco etchesi gen. et sp. nov., from the Upper Jurassic Kimmeridge Clay Formation of Dorset, UK is described. The specimen, a partial, articulated skull and anterior thorax in the Etches Collection of Kimmeridge, Dorset, is exceptionally well preserved on a slab of laminated coccolith limestone and has been expertly prepared. It comprises a near complete skull in articulation with associated anterior vertebral column and dorsal ribs, complete pectoral girdle, fully exposed left forelimb, and some elements of the right forelimb. Other elements present, including an ischiopubis are preserved on separate slabs. Presumed rapid burial of the anterior portion of the specimen in the coccolith substrate has preserved a number of ossified ligaments lying across the vertebral column and associated ribs as well as stomach contents and decayed internal organs. Aspects of the dentition, skull roof bones and the forelimb configuration distinguishes the new specimen from previously described Late Jurassic ichthyosaurs. Autopmorphies for T. etchesi include a large rounded protuberance on the supratemporal bone; a thin L-shaped lachrymal, with a steeply curved posterior border; ~ 70 teeth on the upper tooth row, and deep anterior dorsal ribs. A well resolved phylogenetic analysis shows T. etchesi as a member of a basal clade within Ophthalmosauridae comprising Nannopterygius, Gengasaurus, Paraophthalmosaurus and Thalassodraco. The new specimen adds to the diversity of the Ichthyopterygia of the Kimmeridge Clay Formation and emphasises the important contribution of amateur collectors in palaeontology.

Taphonomic information from the modern vertebrate death assemblage of Doñana National Park, Spain

Modern death assemblages provide insights about the early stages of fossilization and useful ecological information about the species inhabiting the ecosystem. We present the results of taphonomic monitoring of modern vertebrate carcasses and bones from Doñana National Park, a Mediterranean coastal ecosystem in Andalusia, Spain. Ten different habitats were surveyed. Half of them occur in active depositional environments (marshland, lake margin, river margin, beach and dunes). Most of the skeletal remains belong to land mammals larger than 5 kg in body weight (mainly wild and feral ungulates). Overall, the Doñana bone assemblage shows good preservation with little damage to the bones, partly as a consequence of the low predator pressure on large vertebrates. Assemblages from active depositional habitats differ significantly from other habitats in terms of the higher incidence of breakage and chewing marks on bones in the latter, which result from scavenging, mainly by wild boar and red fox. The lake-margin and river-margin death assemblages have high concentrations of well preserved bones that are undergoing burial and offer the greatest potential to produce fossil assemblages. The spatial distribution of species in the Doñana death assemblage generally reflects the preferred habitats of the species in life. Meadows seem to be a preferred winter habitat for male deer, given the high number of shed antlers recorded there. This study is further proof that taphonomy can provide powerful insights to better understand the ecology of modern species and to infer past and future scenarios for the fossil record.

Split-based points from the Swabian Jura highlight Aurignacian regional signatures

The systematic use of antlers and other osseous materials by modern humans marks a set of cultural and technological innovations in the early Upper Paleolithic, as is seen most clearly in the Aurignacian. Split-based points, which are one of the most common osseous tools, are present throughout most regions where the Aurignacian is documented. Using results from recent and ongoing excavations at Geißenklösterle, Hohle Fels and Vogelherd, we nearly tripled the sample of split-based points from 31 to 87 specimens, and thereby enhance our understanding of the technological economy surrounding the production of osseous tools. Aurignacian people of the Swabian Jura typically left spit-based points at sites that appear to be base camps rich with numerous examples of personal ornaments, figurative art, symbolic imagery, and musical instruments. The artifact assemblages from SW Germany highlight a production sequence that resembles that of SW France and Cantabria, except for the absence of tongued pieces. Our study documents the life histories of osseous tools and demonstrates templates for manufacture, use, recycling, and discard of these archetypal artifacts from the Aurignacian. The study also underlines the diversified repertoire of modern humans in cultural and technological realms highlighting their adaptive capabilities.

Static allometry of a small-bodied omnivore: body size and limb scaling of an island fox and inferences for Homo floresiensis

Island dwarfing is a paraphyletic adaptation across numerous mammalian genera. From mammoths to foxes, extreme body size reduction is shared by diverse organisms that migrate to an island environment. Because it largely occurs owing to ecological variables, not phylogenetic ones, skeletal characters in a dwarfed taxon compared with its ancestor may appear abnormal. As a result, allometric patterns between body size and morphological traits may differ for an island dwarf compared with its ancestor. The diminutive Late Pleistocene hominin, Homo floresiensis, displays a unique character suite that is outside of the normal range of variation for any extinct or extant hominin species. To better explain these as ecological traits due to island dwarfing, this research looks at how dwarfing on islands influences limb scaling and proportions in an organism in a similar ecological niche as H. floresiensis. Here, I analyze absolute limb lengths and static allometry of limb lengths regressed on predicted body mass of dwarfed island foxes and their nondwarfed relatives. Dwarfed island foxes have significantly smaller intercepts but steeper slopes of all limb elements regressed on predicted body mass than the mainland gray fox. These allometric alterations produce limbs in the island fox that are significantly shorter than predicted for a nondwarfed gray fox of similar body mass. In addition, the humerofemoral, intermembral, and brachial indices are significantly different. These results provide a novel model for understanding skeletal variation of island endemic forms. Unique body size and proportions of H. floresiensis are plausible as ecological adaptations and likely not examples of symplesiomorphies with Australopithecus sp. Caution should be exerted when comparing an island dwarf with a closely related species as deviations from allometric expectations may be common.

A comprehensive diagnostic approach combining phylogenetic disease bracketing and CT imaging reveals osteomyelitis in a Tyrannosaurus rex

Traditional palaeontological techniques of disease characterisation are limited to the analysis of osseous fossils, requiring several lines of evidence to support diagnoses. This study presents a novel stepwise concept for comprehensive diagnosis of pathologies in fossils by computed tomography imaging for morphological assessment combined with likelihood estimation based on systematic phylogenetic disease bracketing. This approach was applied to characterise pathologies of the left fibula and fused caudal vertebrae of the non-avian dinosaur Tyrannosaurus rex. Initial morphological assessment narrowed the differential diagnosis to neoplasia or infection. Subsequent data review from phylogenetically closely related species at the clade level revealed neoplasia rates as low as 3.1% and 1.8%, while infectious-disease rates were 32.0% and 53.9% in extant dinosaurs (birds) and non-avian reptiles, respectively. Furthermore, the survey of literature revealed that within the phylogenetic disease bracket the oldest case of bone infection (osteomyelitis) was identified in the mandible of a 275-million-year-old captorhinid eureptile Labidosaurus. These findings demonstrate low probability of a neoplastic aetiology of the examined pathologies in the Tyrannosaurus rex and in turn, suggest that they correspond to multiple foci of osteomyelitis.

Great Evening Bat Ia io (Vespertilionidae, Chiroptera) from the Pleistocene of Vietnam (Lang Trang Cave)

A dentary fragment of a great evening bat Ia io Thomas, 1902 found in 2020 in the Pleistocene deposits of the Lang Trang karstic cave in northern Vietnam is described. This rare species of large tropical bats now inhabits Nepal, eastern India, southern China, Thailand, Laos, and Vietnam and as a fossil is known from the Pleistocene of China. In Vietnam the fossil remains of this species have been discovered for the first time. By the total size and lower molar structure, the specimen from the Lang Trang cave is most similar to the subspecies Ia io peninsulata Soisook et al., 2017 that now occurs in southern Thailand.

Arachnid monophyly: Morphological, palaeontological and molecular support for a single terrestrialization within Chelicerata

The majority of extant arachnids are terrestrial, but other chelicerates are generally aquatic, including horseshoe crabs, sea spiders, and the extinct eurypterids. It is necessary to determine whether arachnids are exclusively descended from a single common ancestor (monophyly), because only that relationship is compatible with one land colonisation in chelicerate evolutionary history. Some studies have cast doubt on arachnid monophyly and recast the origins of their terrestrialization. These include some phylogenomic analyses placing horseshoe crabs within Arachnida, and from aquatic Palaeozoic stem-group scorpions. Here, we evaluate the possibility of arachnid monophyly by considering morphology, fossils and molecules holistically. We argue arachnid monophyly obviates the need to posit reacquisition/retention of aquatic characters such as gnathobasic feeding and book gills without trabeculae from terrestrial ancestors in horseshoe crabs, and that the scorpion total-group contains few aquatic taxa. We built a matrix composed of 200 slowly-evolving genes and re-analysed two published molecular datasets. We retrieved arachnid monophyly where other studies did not - highlighting the difficulty of resolving chelicerate relationships from current molecular data. As such, we consider arachnid monophyly the best-supported hypothesis. Finally, we inferred that arachnids terrestrialized during the Cambrian-Ordovician using the slow-evolving molecular matrix, in agreement with recent analyses.

Eocarcinus praecursor Withers, 1932 (Malacostraca, Decapoda, Meiura) is a stem group brachyuran

Beginning with the description by Withers in 1932, Eocarcinus praecursor from the Jurassic has long been considered the oldest representative of the Brachyura. In 2010 Feldmann and Schweitzer re-investigated the specimens of E. praecursor and expressed doubts about the brachyuran nature of this species. Among other characters, the suspected existence of small chelae in the 2nd or 3rd pereopods led them to the conclusion that E. praecursor must be removed from the Brachyura and rather be seen as a representative of the Anomala. However, Anomala also do not possess chelae on the 2nd and 3rd pereopods. This contradiction and other aspects initiated a new investigation of E. praecursor. It can be shown that neither the 2nd nor the 3rd pereopods of E. praecursor are chelate. Furthermore, there are no other derived characters shared with anomalans. By contrast, there are a number of apomorphies shared with Brachyura such as the shape and articulation of the large chelae and the attachment points of the last two pereopods. However, not all apomorphies of the crown group are present yet. Thus, E. praecursor is a stem group representative, which allows statements about individual steps in the evolution of the set of characters of the crown group Brachyura.