PALEONTOLOGY IN OCTOBER, 2024

ABSTRACT

The Barremian-aged Wessex Formation of the Isle of Wight, UK, offers a globally significant glimpse into the sauropod dinosaur faunas of the early Cretaceous. These deposits have yielded specimens of several neosauropod lineages, such as rebbachisaurids, titanosauriforms (including some of the earliest titanosaur remains), and possible flagellicaudatans. Here, we report an undescribed sauropod partial hindlimb from the Wessex Formation (NHMUK PV R16500) and analyse its phylogenetic affinities. This hindlimb preserves the left tibia, astragalus and pes, lacking only a few phalanges. NHMUK PV R16500 can be diagnosed based on two autapomorphies: an unusually high distal end to midshaft transverse width ratio in metatarsals III and IV, and the presence of small bump-like projections located in the centre of the proximal articular surfaces of the unguals of pedal digits I and II. The phylogenetic affinities of NHMUK PV R16500 are uncertain: although our analyses recover it as an early-branching somphospondylan, a single character change moves it to close to Flagellicaudata when extended implied weighting is applied. The possibility of flagellicaudatan affinities for NHMUK PV R16500 implies a potential ghost lineage that survived the Jurassic/Cretaceous boundary; however, we present evidence that the somphospondylan position is more probable and should be preferred.

LINK(S)

https://royalsocietypublishing.org/doi/10.1098/RSOS.240642

https://royalsocietypublishing.org/doi/epdf/10.1098/rsos.240642

ABSTRACT

Understanding of Cretaceous ichthyosaur diversity has substantially increased in recent years; however, Eastern Gondwana’s ichthyosaur fauna is still poorly understood, particularly in New Zealand where only scarce fragmentary material is known. A Cenomanian-aged partial ichthyosaur skeleton has been recovered from the northeastern South Island of New Zealand and is described here. Whilst the specimen is too fragmentary to formally name, this taxon shows an extreme reduction of the basioccipital extracondylar area, a scapula with a prominent acromion process and a strap-like scapula shaft, as well as a complete left pelvic girdle with an elongated depression on the anteroproximal face of the ischiopubis. We suggest that it is a late branching member of the platypterygiid ichthyosaurs, closely related to the Eastern Gondwanan ichthyosaur Platypterygius australis and to many European Cretaceous taxa. However, it appears to be unrelated to the Cretaceous ichthyosaurs of Western Gondwana, suggesting potential regionalism amongst the Gondwanan Cretaceous ichthyosaur populations.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2408391

https://www.tandfonline.com/doi/epdf/10.1080/02724634.2024.2408391?needAccess=true

ABSTRACT

The theropod dinosaur Coelophysis bauri is well known from the famous Rhaetian, Late Triassic mass death assemblage from the Coelophysis Quarry at Ghost Ranch, New Mexico. This research describes the skulls of two small individuals of C. bauri. Both skulls are mostly complete, though they are missing premaxillae, and most posterior skull bones are either missing or badly damaged. Both specimens preserve hyoids, making them excellent candidates for hyoid histology. These two skulls have different proportions from other Coelophysis skulls from Ghost Ranch, especially in the large size of the orbit, short and flat triangular teeth, and thinner bones. These differences are interpreted as representing ontogenetic variation, with these skulls representing skeletally immature, partially developed individuals.

LINK(S)

https://app.pan.pl/article/item/app010852023.html

https://app.pan.pl/archive/published/app69/app010852023.pdf

ABSTRACT

The severe greenhouse climate and seasonality of the early to mid-Late Triassic are thought to have limited terrestrial diversity at lower latitudes, but direct adaptations to these harsh conditions remain limited in vertebrates at the palaeoequator. Here, we present Ninumbeehan dookoodukah gen. et sp. nov., an early amphibian with specialized adaptations for seasonal estivation from the upper Jelm Formation of the Late Triassic of Wyoming, USA. Ninumbeehan are found in an association of vertebrate estivation burrows across a locally dense horizon, offering insights into the evolution and ecology of vertebrates amid the challenging conditions of low-latitude Late Triassic ecosystems. Estivation chambers were excavated within point bar deposits of an ephemeral river system, recording the cyclical signature of Triassic megamonsoons and documenting a vertebrate response to annual climate extremes across tens to hundreds of seasons. Phylogenetic analysis recovers Ninumbeehan within a group of temnospondyls characterized by fossorial adaptation, underscoring the widespread adoption of burrowing and estivation in total group Lissamphibia. Ninumbeehan hints at the pivotal role seasonal dynamics played in shaping amphibian evolution.

LINK(S)

https://royalsocietypublishing.org/doi/10.1098/rspb.2024.1041

ABSTRACT

Three new specimens of protoceratopsid skulls have been discovered recently from the Late Cretaceous Wulansuhai Formation (Campanian) at Bayan Tal locality in Alxa Right Banner, western Inner Mongolia Autonomous Region, northern China. The skull is relatively large, with premaxillary teeth absent. The craniocaudally arranged ridge on the lateral surface of maxilla is generally straight, and comparatively reduced. The ventral edge of dentary is nearly straight. These specimens show the representative characters only present in Protoceratops hellenikorhinus , thus should be assigned to this taxon. Only one genus and species of Protoceratopsidae has been confirmed, ie Protoceratops hellenikorhinus , at Bayan Tal locality. This locality becomes the second site yielding P. hellenikorhinus , following Bayan Mandahu locality in Urad Rear Banner, western Inner Mongolia. This protoceratopsid species was the dominant element among the dinosaur faunas at both Bayan Tal and Bayan Mandahu localities, which provides more paleontological evidences for the Late Cretaceous dinosaur faunal similarity between the two sites. P. hellenikorhinus has been only known at Bayan Tal and Bayan Mandahu localities during the Campanian, Late Cretaceous. This fact indicates that there may have existed a vast region in similar paleoenvironment across the western Inner Mongolia at that time, and that the dinosaurs could exchange easily within the region.

LINK(S)

https://www.xbdz.net.cn/article/doi/10.12401/j.nwg.2024066

https://www.xbdz.net.cn/cn/article/pdf/preview/10.12401/j.nwg.2024066.pdf

ABSTRACT

A locomotor system that can function across different environmental conditions and produce a range of performances is one of the most critical abilities needed for extant and extinct animals in order to survive and maximise their competitive fitness. Recent engineering-inspired paleontological studies have reconstructed feasible locomotor patterns in extinct animals. However, it is still challenging to describe how extinct animals successfully adjust their locomotor patterns to new situations (e.g., changes in locomotor speed and morphology). In this study, we develop a novel reconstruction method based on a bio-inspired control system. We focus on plesiosaurs, an extinct aquatic reptile group which has two pairs of flipper-shaped limbs, and demonstrate that a highly optimised, flexible locomotor pattern for all four flippers can be reconstructed based on a decentralized control scheme formulated from extant animals’ locomotion. The results of our robotic experiments show that a simple, local sensory feedback mechanism allows the plesiosaur-like robot to exploit the fluid flow between the flippers and generate efficient swimming patterns in response to changes in locomotor conditions. Our new method provides further evidence how decentralized control systems can produce a pathway between extinct and extant animals in order to understand the how extinct animals moved and how these movement patterns may have evolved.

LINK(S)

https://www.nature.com/articles/s41598-024-55805-z

https://www.nature.com/articles/s41598-024-55805-z.pdf

ABSTRACT

Ontogenetic change is a major source of phenotypic variation among members of a species and is often of greater magnitude than the anatomical differences that distinguish closely related species. Ontogeny has therefore become a problematic confounding variable in vertebrate paleontology, especially in study systems distant from extant crown clades, rendering taxonomic hypothesis testing (a fundamental process in evolutionary biology) rife with difficulty. Paleontologists have adopted quantitative methods to compensate for the perception that juvenile specimens lack diagnostic apomorphies seen in their adult conspecifics. Here, I critically evaluate these methods and the assumptions that guide their interpretation using a μCT dataset comprising growth series of American and Chinese alligator. I find that several widespread assumptions are scientifically unjustifiable, and that two popular methods—geometric morphometrics and cladistic analysis of ontogeny—have unacceptably high rates of type II error and present numerous procedural difficulties. However, I also identify a suite of ontogenetically invariant characters that differentiate the living species of Alligator throughout ontogeny. These characters overwhelmingly correspond to anatomical systems that develop prior to (and play a signaling role in) the development of the cranial skeleton itself, suggesting that their ontogenetic invariance is a consequence of the widely conserved vertebrate developmental program. These observations suggest that the architecture of the cranium is fixed early in embryonic development, and that ontogenetic remodeling does not alter the topological relationships of the cranial bones or the soft tissue structures they house. I propose a general model for future taxonomic hypothesis tests in the fossil record, in which the hypothesis that two specimens different ontogenetic stages of a single species can be falsified by the discovery of character differences that cannot be attributed plausibly to ontogenetic variation.

LINK(S)

https://www.biorxiv.org/content/10.1101/2024.10.25.620216v1

https://www.biorxiv.org/content/biorxiv/early/2024/10/28/2024.10.25.620216.full.pdf

ABSTRACT

Spinosaurids were common elements from dinosaur faunas during the Early Cretaceous in western Europe, with isolated teeth being the most common fossils registered in the fossil record. Here, some isolated spinosaurid teeth from the municipality of Galve (province of Teruel, Spain) are studied. They come from the lower Barremian (Lower Cretaceous) deposits of the Camarillas Formation of Western Maestrazgo Basin. These fossils are described and compared with related taxa, and analyzed with morphometric (discriminant and cluster analyses) and cladistic methods when possible. One tooth was classified as Spinosauridae indet., while the other two specimens were assigned to Baryonychinae indet. and Spinosaurinae indet., respectively. The indeterminate baryonychine tooth closely resembles a particular morphotype with an unserrated mesial carina and fluted enamel on both lingual and labial surfaces present in the Iberian Peninsula, unlike those of Baryonyx and Iberospinus. The spinosaurine tooth represents a new morphotype, which is distinguished from other teeth found in the Barremian of Teruel for having mesial and distal unserrated carinae and fluted enamel on both the lingual and labial surfaces. These teeth not only suggest the presence of at least one baryonychine and one spinosaurine taxa during the early Barremian in the eastern Iberian Peninsula, but also support their presence in fluvial systems with some marine influence where other dinosaurs have been broadly identified, such as styracosternan ornithopods.

LINK(S)

https://link.springer.com/article/10.1007/s41513-024-00269-3

ABSTRACT

Body impressions of ingested organisms preserved in coprolites are exceedingly rare in the fossil record. Only two previous publications report on the preservation of an impression of the body of an organism in a coprolite. Herein, the impression of the dorsal surface of the exoskeleton of a new genus and species of cymothoid isopod, Calverteca osbornei, preserved in a vertebrate coprolite is described. The coprolite probably originated from the Newport News beds of the lower Miocene Calvert Formation of the Chesapeake Group of Virginia, USA. This coprolite is the first report in the fossil record of the impression of the body of a crustacean (Arthropoda) preserved in a coprolite. This is also the first report of an isopod within the Chesapeake Group. The producer of the original fecal mass is unknown, although a fish seems the most likely given that cymothoid isopods parasitize the oral cavities of bony fishes.

LINK(S)

https://palaeo-electronica.org/content/2024/5363-isopod-impression-in-a-coprolite

https://palaeo-electronica.org/content/pdfs/1371.pdf

ABSTRACT

A new oviraptorosaur, Yuanyanglong bainian gen. et sp. nov. is described based on two specimens recovered from the Lower Cretaceous Miaogou Formation of the Maortu locality in Chilantai, Inner Mongolia, China. This new species is intermediate in morphology between the earliest-diverging and late-diverging oviraptorosaurs, and our phylogenetic analysis supports it as a sister taxon to the clade formed by Avimimidae and Caenagathoidea. Notably, this new early-diverging oviraptorosaur has an ilium with an extremely short postacetabular process and hindlimbs with proportionally elongate and fused lower segments, a character combination unknown among other oviraptorosaurs but common in wading birds, suggesting a potential ecology involving wading. Preserved gastroliths similar to Caudipteryx suggest a gastric mill function in our new species, and our preliminary observations indicate potential discrepancies in the digestion mode of early- and late-diverging oviraptorosaurs.

LINK(S)

https://www.sciencedirect.com/science/article/abs/pii/S0195667124001964?via%3Dihub

ABSTRACT

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.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2403577#abstract

https://www.tandfonline.com/doi/epdf/10.1080/02724634.2024.2403577?needAccess=true 

ABSTRACT

Body fossils set limits on feasible reconstructions of functional capacity and behavior in theropod dinosaurs, but do not document in-life behaviors. In contrast, trace fossils such as footprints preserve in-life behaviors that can potentially test and enhance existing reconstructions. Here, we demonstrate how theropod trackways can be used as indirect evidence of pre-avian aerial behavior, expanding the approaches available to study vertebrate flight origins. This involved exploring the behavioral implications of a two-toed Cretaceous-aged theropod trackway produced by a small, bird-like microraptorine moving at high speed. Applying first principle running biomechanics, we were able to conclude that the trackway is atypical, indirectly evidencing pre-avian aerial behavior. This trackway documents the evidence of wing-assisted aerodynamic force production during locomotion, supporting a broader distribution of this behavior than currently known. These findings support previously proposed aerial behavior in early bird-like theropods, showing how trackways will help to deepen our understanding of theropod flight origins.

LINK(S)

https://www.pnas.org/doi/10.1073/pnas.2413810121

https://www.pnas.org/doi/pdf/10.1073/pnas.2413810121

ABSTRACT

The Lower Member of the Ituzaingó Formation (LMIF), fluvial in origin and assigned to the Upper Miocene, contains a conglomerate level known as “Mesopotamiense” or “Conglomerado osífero” that has yielded a rich fauna of vertebrates. The aim of this contribution is to describe a titanosaurian dinosaur eggshell fragment recovered from the LMIF at the locality of Toma Vieja (western Entre Ríos Province), discussing its paleogeographic history and implications. Fragments of eggshells referred to Titanosauria are frequent from litostratigraphic units of the Upper Cretaceous of western Uruguay (e.g., Guichón, Mercedes, and Queguay Formations). Besides, a fragment of eggshell recovered from the Puerto Yeruá Formation (Upper Cretaceous) at eastern Entre Ríos Province was described. Geophysical data from the Entre Ríos Province allow to propose the presence of a Lower Cretaceous field of extensional tectonic stresses that generated structural lineaments with a E-W and ENE-WSW trend. This ancient penetrative Cretaceous tectonic framework would have exerted control on the shape of the basin and sediment flow patterns and subsequent sedimentation, by promoting the generation of accommodation space over the late Paleogene and the Neogene. The phenomenon would have conditioned the deposition of the Fray Bentos Formation, the subsequent marine Paraná Formation, and the sedimentation of the LMIF, with source materials coming from the east. Thus, it is hypothesized that the fragment of eggshell of Titanosauria would come from the eastern area of the basin (western Uruguay) as a consequence of the existence of a paleohydric system with predominantly E-W and ENE-WSW directions. This late Neogene system would have been controlled by inherited Cretaceous structural lineaments with orientations similar to those that also govern the current fluvial systems of western Uruguay, developed on the Mesozoic substrate.

LINK(S)

https://www.sciencedirect.com/science/article/abs/pii/S0895981124004267

ABSTRACT

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.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2402042

ABSTRACT

In 2000, a small sauropod trackway was discovered in the Upper Cretaceous Jindong Formation (Cenomanian) at Eosin-ri, Goseong County, South Korea. This quadrupedal trackway consists of 34 very small sauropod footprints, with an average manus width of 10.0 cm and pes length of 12.8 cm, showing low heteropody (mean IPS/IMS: 1.38). The manus tracks are oval to kidney-shaped, while the pes tracks are generally subcircular to V-shaped, lacking distinct claw marks. The trackway shows a medium to wide gauge (mean PTR: 38.8 %; WAP/PL: 1.18). The small footprint size and estimated trackmaker body size suggest that the trackmaker was an early juvenile titanosauriform sauropod based on the contemporaneous sauropod taxa of East Asia. Sauropod trackways reported from the Jindong Formation, including the Eosin-ri trackway, exhibit a tendency for narrower trackway gauges as pes length increases. This negative correlation between trackmaker size and trackway gauge may imply ontogenetic or behavioral variations within the same clade of sauropods or differences in gait or body plan amongst different sauropod taxa.

LINK(S)

https://www.sciencedirect.com/science/article/abs/pii/S0195667124001952?via%3Dihub

ABSTRACT

A new specimen, MAU-Pv-PH-453, comprising an isolated femur from the Plottier Formation (Coniacian-Santonian), northern Patagonia, is described here. Its characteristics, i.e., an anteriorly curved diaphysis; fused lesser and greater trochanters forming a trochanteric crest; a prominent medially directed head; and the absence of a fourth trochanter, allow us to identify it as belonging to a maniraptoran theropod. Among Patagonian maniraptorans, MAU-Pv-PH-453 shares similarities with alvarezsaurians, such as the absence of a posterior trochanter, a trochanteric shelf, and the fourth trochanter. However, in Patagonian alvarezsaurs, the lesser and greater trochanters are generally separated by a cleft. Notably, MAU-Pv-PH-453 exhibits some features seen in femora of parvicursorine alvarezsaurids, including a proximally projected trochanteric crest and an L-shaped profile in proximal view. However, MAU-Pv-PH-453 presents differences with parvicursorines, such as a knob partially separating the lesser and greater trochanters. Phylogenetically, MAU-Pv-PH-453 may have parvicursorine affinities, although its fragmentary nature might generate a bias in its phylogenetic position. Due to the lack of more diagnostic characters, MAU-Pv-PH-453 is assigned to Alvarezsauria indet. This material represents the second theropod record from the Plottier Formation and it could fill a temporal gap (between Coniacian and Santonian) in the record of Upper Cretaceous Patagonian alvarezsaurians.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2414206

ABSTRACT

Here we describe a new ornithopod species, Emiliasaura alessandrii gen. et sp. nov. from Valanginian rocks (Early Cretaceous) of northwestern Patagonia. This new taxon exhibits affinities with the Rhabdodontomorpha and is primarily represented by two specimens of mid-sized ornithopods collected from different sites and stratigraphical levels of the Mulichinco Formation. The holotype specimen MLL-Pv-001 includes the coracoid, the proximal end of a scapula, a humerus and a complete right hind limb, whereas the paratype specimen MLL-Pv-006 preserves vertebral elements, haemal arches, an incomplete pelvis, and nearly complete hind limbs. The new taxon has an anteroposteriorly elongate ilium with a sigmoidal dorsal border and broad brevis shelf, a femur shaft with an extensive, mid-shaft positioned fourth trochanter, and a second pedal digit with a short, robust, blunt ungual phalanx similar to those in Ankylopollexia ornithopods. The new ornithopod taxon formed part of a diverse dinosaur association from the Mulichinco Fm that includes dicraeosaurid sauropods and carcharodontosaurid theropods, and represents the first South American record of a rhabdodontomorph, and the oldest and most primitive representative of this clade.

LINK(S)

https://www.sciencedirect.com/science/article/abs/pii/S0195667124002003

ABSTRACT

The Upper Cretaceous Ganzhou Basin of Jiangxi Province, South China is among one of the richest egg fossil sites in the world and yields abundant exquisite egg clutches and embryonic eggs, especially in oviraptorosaurs. Hadrosaurian, troodontid, and potential dromaeosaurid egg fossils were also reported, though they were rare. All these reported eggs vary in morphology but have relatively large sizes. Here, we report a partial egg clutch with six complete small eggs from the Upper Cretaceous Tangbian Formation of Ganzhou City, Southeast China. The microstructure of the eggshell indicates that it can be assigned to Ovaloolithidae. Hence, we established a new ootaxon, Minioolithus ganzhouensis oogen. et oosp. nov. based on a unique combination of characters, including a small egg size, irregular egg arrangement, worm-like and nodular ornamentation, and a gradual boundary between two structural layers. The egg morphology and eggshell microstructure support it to be the smallest known non-avian theropod egg up to date. This discovery increases the diversity of dinosaur eggs in the Late Cretaceous and is significant for our understanding of the evolution of theropods in the Late Cretaceous.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2409873

ABSTRACT

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.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2396821

ABSTRACT

Ankylosaurids but not nodosaurids possess a suite of neomorphic elements fused to the posterior border of the skull roof. Previous authors have offered conflicting descriptions of these elements, leading to ongoing confusion over their morphology, developmental origin, and homologies. They have been described both as secondary dermal additions and as outgrowths of known skull elements. However, they are demonstrably neomorphic and were incorporated into the skull early in ankylosaurid evolution. The six elements—three per side—are herein termed the supranuchal, postsquamosal, and postquadratojugal and form the posterior margin of the skull on each side (in some taxa, the parietal also reaches the posterior border). They do not overlie the squamosal or quadratojugal but rather articulate with them. Other neomorphic elements including the supraorbitals and supranarial ossifications have been described previously. The squamosal proper is a small element in the skull roof with a well-defined cotylus ventrally for articulation with the quadrate. The three neomorphs likely originated as a cervical half-ring or simply as a series of six cervical osteoderms situated just posterior to the skull in ancestral ankylosaurs.

LINK(S)

https://www.sciencedirect.com/science/article/abs/pii/S0195667124001939

ABSTRACT

Protosphyraena is one of the most widespread Cretaceous actinopterygian genera, with numerous species described primarily from the Upper Cretaceous of North America and Western Europe. However, most of the species are known from fragmentary and anatomically non-overlapping material, making the alpha taxonomy of this genus extremely problematic. Here we describe the first finds of Protosphyraena from the Albian of the Caucasus, and reassess the historical specimens from the Cenomanian of the Kursk Region of Russia. In an attempt to assign Russian specimens to a particular species, we review the global records and tangled taxonomy of Protosphyraena. The type species, P. ferox, is unambiguously known from teeth, cranial fragments and mandibles. The posteriorly directed rostral teeth of the type species cast doubt on the validity of Australopachycormus originally erected based on this feature. Our observations support the assignments of the historical Russian Cenomanian specimens to P. ferox and P. tenuirostris. We do not find sufficient cause to refer all isolated fins from Europe to P. ferox, as suggested by recent research. Instead, the species initially proposed by Agassiz for isolated fins from the English Chalk are available, and the fins of Protosphyraena from the Caucasus are consistent with one of these species, Protosphyraena gibberula comb. nov. Our findings indicate that Protosphyraena was widespread already in the late Early Cretaceous. Moreover, the youngest occurrence of Protosphyraena in Europe, a pectoral fin from the Maastrichtian of Belgium, demonstrates unique features and is thus referred to a new species, Protosphyraena terminata sp. nov.

LINK(S)

https://www.sciencedirect.com/science/article/pii/S0195667124001927?via%3Dihub
PDF

ABSTRACT

The Carboniferous myriapod Arthropleura is the largest arthropod of all time, but its fossils are usually incomplete, limiting the understanding of its anatomy, ecology, and relationships. Micro–computed tomography applied to exceptionally preserved specimens from the Carboniferous Montceau-les-Mines Lagerstätte (France) reveals unprecedented details of its functional anatomy, such as the head and mouthparts. Arthropleura shares features with both millipedes and centipedes. Total-evidence phylogeny combining morphological and transcriptomic data resolves Arthropleura alone as a stem group millipede, but the inclusion of the highly incomplete Siluro-Devonian Eoarthropleura draws it deeper into the myriapod stem. Arthropleura suggests transitional morphology between clades united primarily by molecular information and underscores the value of total-evidence phylogenetics to understanding evolutionary history.

LINK(S)

https://www.science.org/doi/10.1126/sciadv.adp6362

ABSTRACT

Enantiornithines were the most diverse group of birds during the Cretaceous, comprising over half of all known species from this period. The fossil record and subsequently our knowledge of this clade is heavily skewed by the wealth of material from Lower Cretaceous deposits in China. In contrast, specimens from Upper Cretaceous deposits are rare and typically fragmentary, yet critical for understanding the extinction of this clade across the K-Pg boundary. The most complete North American Late Cretaceous enantiornithine is Mirarce eatoni, a member of the diverse clade Avisauridae. Except for Mirarce, avisaurids are known only from isolated hindlimb elements from North and South America. Here we describe three new enantiornithines from the Maastrichtian Hell Creek Formation, two of which represent new avisaurid taxa. These materials represent a substantial increase in the known diversity of Enantiornithes in the latest Cretaceous. Re-examination of material referred to Avisauridae through phylogenetic analysis provides strong support for a more exclusive Avisauridae consisting of six taxa. Exploration of the functional morphology of the avisaurid tarsometatarsus indicates potential strong constriction and raptorial attributes. The lower aspect ratio of the tarsometatarsus facilitates a more biomechanically efficient lever system which in extant birds of prey equates to lifting proportionally heavier prey items. In addition, the proportional size and distal position of the m. tibialis cranialis tubercle of the tarsometatarsus is similar to the morphology seen in extant birds of prey. Together with the deeply-grooved metatarsal trochlea facilitating robust and likely powerful pedal digits, morphologies of the hindlimb suggest avisaurids as Late Cretaceous birds of prey.

LINK(S)

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0310686

ABSTRACT

The Kem Kem Group is a lowermost lithostratigraphic unit from the Upper Cretaceous that extends along the border between Algeria and Morocco, in the northern region of Africa. This geological unit has yielded several tetrapod fossils, including a well-represented assemblage of theropod dinosaurs, after more than eight decades of research. Here, we report new occurrences of spinosaurid theropods from the spinosaurine clade in the Kem Kem Group by providing anatomical descriptions and taxonomic identifications of 11 new specimens derived from the Tafilalt region of Morocco. Among the findings, we describe a cervical vertebra of Sigilmassasaurus, in addition to several cranial, axial, and appendicular elements that can safely be attributed to Spinosaurinae. Moreover, based on a unique combination of characteristics, we also describe an isolated and partial ischium belonging to an indeterminate carcharodontosaurid. We also deliver a detailed redescription of one of the most complete snouts of a spinosaurine known to date. Therefore, the theropod dinosaurs of the Kem Kem Group show considerable diversity, but many questions, especially related to the diversity of spinosaurids and the general abundance of carnivorous dinosaurs in this region, remain unclear until new materials are discovered and complete descriptions are made.

LINK(S)

https://academic.oup.com/zoolinnean/article-abstract/202/2/zlae109/7816073

ABSTRACT

Carcharodontosaurids were gigantic terrestrial dinosaurs and top predators of dinosaur faunas in Gondwanan landmasses during the “Mid”-Cretaceous Period. Despite their wide geographical and stratigraphical distribution, essential parts of their anatomy are still poorly known. The present contribution aims to describe a new partial skeleton of the carcharodontosaurid Taurovenator violantei, which was previously known only by an isolated postorbital bone coming from Cenomanian–Turonian beds of northern Patagonia, Argentina. The neck of Taurovenator is composed of notably high anterior cervicals, bearing neural spines with expanded, flange-like dorsal tips which are successively imbricated. This condition has been reported previously in the carcharodontosaurid Acrocanthosaurus, but its occurrence in Taurovenator and other members of the clade suggests it may represent a synapomorphy of this theropod family. This unique neck morphology was probably related to strong modifications in musculature and restriction in the range of movements within the neck, but not with the head. The new specimen also affords valuable anatomical information on the forelimb of Patagonian carcharodontosaurids. As in other giganotosaurines, Taurovenator shows strongly reduced forelimbs, particularly the forearm, showing hand elements with elongated non-ungual phalanges, and well-marked articular surfaces and muscular insertions, suggesting highly movable digits. This new specimen of Taurovenator allows us to expand anatomical and morpho-functional discussions about the carcharodontosaurid clade.

LINK(S)

https://link.springer.com/article/10.1007/s00114-024-01942-4

ABSTRACT

The Morrison Formation of the western United States is well-known for its high diversity of sauropod dinosaurs. The Howe-Stephens Quarry in northern Wyoming is one of several quarries which has yielded several associated to completely articulated dinosaur specimens, among which a semi-articulated diplodocid specimen, MAB011899, which was excavated in 1993. This diplodocid specimen is represented by posterior cervical, dorsal, sacral, and anterior caudal vertebrae, multiple thoracic ribs, two chevrons, a left coracoid, a left ilium, both pubes and ischia, a left femur, a left tibia, and a left fibula. Through comparative anatomy, we interpret this specimen as a new species of diplodocine sauropod, Ardetosaurus viator gen. et sp. nov. Unambiguous autapomorphies include paired accessory laminae in the spinoprezygapophyseal fossae of posterior cervical and anterior dorsal vertebrae, bifurcating anterior centrodiapophyseal laminae in the anterior dorsal vertebrae, fossae present in the centropostzygapophyseal laminae of the second dorsal vertebra, a low vertebral height/centrum length ratio of the posterior dorsal vertebrae and reduced to absent centroprezygapophyseal laminae in the anterior caudal vertebrae. Local autapomorphic features include single centroprezygapophyseal laminae in the posterior cervical vertebrae and a highly elliptical cross-section of the femoral midshaft. Ardetosaurus viator is the first skeletally mature sauropod specimen described from the Howe-Stephens Quarry. This specimen provides insight into serial variation of vertebral laminae and laminar transitions. Finally, the peculiar morphology of the -often not preserved- first chevronNot is described in detail, and its possible use in studying sexual dimorphism in sauropods is discussed.

LINK(S)

https://palaeo-electronica.org/content/2024/5327-new-diplodocine-sauropod

https://palaeo-electronica.org/content/pdfs/1380.pdf

ABSTRACT

The initial stages of the evolutionary history of peratheriines, the European herpetotheriid metatherians, are largely unknown, primarily due to their limited morphological dental disparity throughout the Palaeogene, coupled with significant intraspecific variation. Based on eleven molars, we document a new early peratheriine species, Peratherium musivum sp. nov. which is larger than and morphologically similar to the earliest peratheriine, Peratherium constans (MP7). Subtle molar characters are shared with the largest early Eocene peratheriine, Peratherium maximum comb. nov. We illustrate the importance of studying possible changes in molar cusp – basin proportions and correlated characters that occured during peratheriine evolution. Peratherium musivum sp. nov. which spanned only part of the MP7-MP8 + 9 time interval, and the ~MP8 + 9 Peratherium maximum comb. nov. were probably widespread in Western Europe. The description of a well-preserved mandible of the latter, from La Borie (~MP8 + 9), reveals original features concerning relative size and shape of dental alveoli, partly corroborated using isolated molars. These traits are absent in the younger, most representative species of both peratheriine genera, Peratherium and Amphiperatherium. Based on the aforementioned data and a critical review, it is demonstrated that peratheriine genera lack consistent definitions, so that the Peratherium/Amphiperatherium dichotomy is plausibly inapplicable to early Eocene representatives.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2403602

ABSTRACT

This study focuses on a rare sail-shaped macrofossil, Alienum velamenus gen. & sp. nov. from the Jiangchuan Biota in Yunnan Province, China. The new species presented here possesses an unique bipartite body consisting of a wide unbranched, asymmetrical sail-shaped anterior section and a small narrow tail-like posterior section. The macrofossil of the new species is preserved through carbonaceous compression. Its appearance is different from known macroalgae but similar to Vetulicolia from the early Cambrian Chengjiang Biota. The anterior section of the new species, which is broad and smooth, shows only indistinctly arranged suspected gill slits and a nearly horizontal pharyngeal groove, without significant segmented structures. Owing to lack of samples, the specific biological properties and taxa of the new species are still undefined. The discovery of Alienum velamenus indicates that the Jiangchuan Biota is an exceptional lagerstätte with great potential for the preservation of Precambrian early life through carbonaceous compression. Furthermore, the Jiangchuan Biota shows significant differences in species diversity from the Miaohe Biota of the Doushantuo Formation and the Shibantan Biota of the Dengying Formation in the Three Gorges area of Hubei Province.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2403588

ABSTRACT

Early Cretaceous ichthyosaurs were globally distributed pelagic marine reptiles, but many remains are fragmentary, creating a Northern Hemisphere diversity bias. A rich Hauterivian locality near the Tyndall Glacier inside Torres del Paine National Park in southern Chile yields important new data regarding ichthyosaurian diversity along the Pacific margin of Gondwana. These new data will contribute to clarifying questions regarding ichthyosaur taxonomy and the palaeobiogeographical relationships between the southern Gondwanan and Northern Hemisphere ichthyosaur groups during the Early Cretaceous. Here, we describe three new ichthyosaur specimens from this locality. Two of them are referred to Myobradypterygius hauthali, expanding the distribution of this species from the Barremian of Argentina to the Hauterivian of the Chilean Patagonia. This material shows that M. hauthali differs from Platypterygius platydactylus in forefin construction and scapular morphology, supporting its classification as a separate genus within Platypterygiinae. The third specimen is a large-bodied indeterminate ophthalmosaurine ichthyosaur. This record represents the southernmost record of Ophthalmosaurinae and the first occurrence of this group from the Cretaceous of the Southern Hemisphere. These discoveries show that ophthalmosaurines and platypterygiines continued to occur sympatrically in southernmost Gondwana during the Early Cretaceous, expanding the pattern documented in Europe to the Pacific region.

LINK(S)

https://academic.oup.com/zoolinnean/article-abstract/202/2/zlae106/7811423

ABSTRACT

An incomplete, but large hollow bone is identified as pterosaurian on account of its pneumatic nature, thin bone wall, palaeohistology and the characteristic surface texture of the peridermal bone. Despite being incomplete it is tentatively identified as a ?left ulna, and is remarkable for its size. Coming from the lower Middle Jurassic Lincolnshire Limestone Formation of Rutland, eastern England, this is the first record anywhere in the World of a Bajocian pterosaur, and probably the first pterosaur recorded from Rutland. It is most likely from Discites to Laeviuscula zones part of the lower Bajocian succession, and represents one of the largest Jurassic pterosaurs yet recorded, with a wingspan tentatively estimated at between 3.5 and 4.0 m. The taxonomic identity of the new specimen is uncertain, but it is likely allied to the Pterodactyloidea on account of its size, although presently it remains Pterosauria fam. et gen., et sp. indet.

LINK(S)

https://www.sciencedirect.com/science/article/pii/S0016787824000555

ABSTRACT

Mass extinctions are considered to be quintessential examples of Court Jester drivers of macroevolution, whereby abiotic pressures drive a suite of extinctions leading to huge ecosystem changes across geological timescales. Most research on mass extinctions ignores species interactions and community structure, limiting inference about which and why species go extinct, and how Red Queen processes that link speciation to extinction rates affect the subsequent recovery of biodiversity, structure and function. Here, we apply network reconstruction, secondary extinction modelling and community structure analysis to the Early Toarcian (Lower Jurassic; 183 Ma) Extinction Event and recovery. We find that primary extinctions targeted towards infaunal guilds, which caused secondary extinction cascades to higher trophic levels, reproduce the empirical post-extinction community most accurately. We find that the extinction event caused a switch from a diverse community with high levels of functional redundancy to a less diverse, more densely connected community of generalists. Recovery was characterised by a return to pre-extinction levels of some elements of community structure and function prior to the recovery of biodiversity. Full ecosystem recovery took ~7 million years at which point we see evidence of dramatically increased vertical structure linked to the Mesozoic Marine Revolution and modern marine ecosystem structure.

LINK(S)

https://www.nature.com/articles/s41467-024-53000-2

https://www.nature.com/articles/s41467-024-53000-2.pdf

ABSTRACT

The evolution of the human hand is a topic of great interest in paleoanthropology. As the hand can be involved in a vast array of activities, knowledge regarding how it was used by early hominins can yield crucial information on the factors driving biocultural evolution. Previous research on early hominin hands focused on the overall bone shape. However, while such approaches can inform on mechanical abilities and the evolved efficiency of manipulation, they cannot be used as a definite proxy for individual habitual activity. Accordingly, it is crucial to examine bone structures more responsive to lifetime biomechanical loading, such as muscle attachment sites or internal bone architecture. In this study, we investigate the manual entheseal patterns of Australopithecus afarensis, Australopithecus africanus, and Australopithecus sediba through the application of the validated entheses-based reconstruction of activity method. Using a comparative sample of later Homo and three great ape genera, we analyze the muscle attachment site proportions on the thumb, fifth ray, and third intermediate phalanx to gain insight into the habitual hand use of Australopithecus. We use a novel statistical procedure to account for the effects of interspecies variation in overall size and ray proportions. Our results highlight the importance of certain muscles of the first and fifth digits for humanlike hand use. In humans, these muscles are required for variable in-hand manipulation and are activated during stone-tool production. The entheses of A. sediba suggest muscle activation patterns consistent with a similar suite of habitual manual activities as in later Homo. In contrast, A. africanus and A. afarensis display a mosaic entheseal pattern that combines indications of both humanlike and apelike manipulation. Overall, these findings provide new evidence that some australopith species were already habitually engaging in humanlike manipulation, even if their manual dexterity was likely not as high as in later Homo.

LINK(S)

https://www.sciencedirect.com/science/article/pii/S004724842400099X

ABSTRACT

For decades, the interrelationships of the extant crocodylians Gavialis gangeticus and Tomistoma schlegelii have been debated, with only recent morphological phylogenetic analyses recovering the sister-taxon relationship between these two gavialoid species that has long been apparent in topologies based on molecular data. Several extinct species from the Mediterranean region are currently assigned to Tomistoma; however, their phylogenetic placement is labile, and often they do not form a clade with Tomistoma schlegelii. Here, we present a revision of Tomistoma dowsoni from the Early Miocene of Egypt and Libya, based on the type specimen (a partial snout and mandible) and referred material, including a nearly complete skull. These specimens show no notable anatomical differences and diagnostic features include: (1) a heart-shaped naris; (2) a prefrontal and lacrimal that are equidimensional in anteroposterior length; and (3) a prominent posterior process of the supraoccipital with a convex posterior margin. Maximum parsimony analysis, under both equal and extended implied weighting, recovers Tomistoma dowsoni as a phylogenetically nested gavialine, distantly related to Tomistoma schlegelii and other Mediterranean species currently referred to Tomistoma. Instead, Tomistoma dowsoni forms a sister-taxon relationship with Eogavialis andrewsi, from the Late Miocene of Kenya. Given that this clade does not consistently cluster with the type species of Eogavialis, and that Tomistoma dowsoni is diagnostic and clearly not referrable to Tomistoma, we herein erect the genus Sutekhsuchus, with the new combination Sutekhsuchus dowsoni. Our phylogenetic analyses recover the European Miocene gavialoids in a monophyletic group with the North American Thecachampsa, forming a clade of early-diverging gavialines that underwent transoceanic dispersal. We also recover a monophyletic group of thoracosaurs, comprising Eothoracosaurus, Portugalosuchus, and Thoracosaurus, which is expanded to include other Late Cretaceous–Early Paleogene European, North American, and North African species under extended implied weighting. https://zoobank.org/urn:lsid:zoobank.org:pub:2DE71417-8088-4749-8672-72E4A40C0B39

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/14772019.2024.2384548

ABSTRACT

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 Bun Ameer Khatoon, Chakwal district, and Hasnot, Jhelum district, Punjab, Pakistan. These outcrops belong to the Chinji Formation and Dhok Pathan Formation, respectively, of lower to middle Siwaliks, dated as Middle to Late Miocene in age. The presence of fossil fauna that primarily fed on herbaceous, grassy, and bushy vegetation suggests that both Dhok Bun Ameer Khatoon and Hasnot were dominated by mixed woodland habitats. These localities have a very rich fossil fauna and the cranium of Vishnutherium priscillum is the first that has been reported from Dhok Bun Ameer Khatoon.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2376241

ABSTRACT

A new ornithocheirid pterosaur, Akharhynchus martilli gen. et. sp. nov. from the Ifezouane Formation, Kem Kem Group, of Morocco is herein described, based on a well-preserved anterior rostrum fragment. It is assigned to a new genus based on one autapomorphy and a unique combination of synapomorphies, including the following characters: the medial rims of the first alveoli pair contact each other, the first alveoli pair are 50% smaller than the second alveoli pair. Comparative anatomy and a phylogenetic analysis demonstrate that Akharhynchus has affinities with Tropeognathus within the Tropeognathinae.

LINK(S)

https://www.sciencedirect.com/science/article/pii/S0195667124001885