PALEONTOLOGY IN SEPTEMBER, 2024

ABSTRACT

Investigations regarding the early evolutionary history of bird-line archosaurs have undergone significant advancements in recent years. However, controversies remain, especially regarding the phylogenetic position of “silesaurids”. Whereas some hypotheses place these archosaurs as the sister-group to dinosaurs, others suggest that “silesaurids” are early ornithischian dinosaurs. Despite the phylogenetic disputes, “silesaurids” are a crucial group for comprehending the origins and early evolution of dinosaurs. In the present study, a new “silesaurid” from the Middle-Upper Triassic of Southern Brazil is described. Gondwanax paraisensis gen. et sp. nov. comes from the Dinodontosaurus Assemblage Zone of the Santa Maria Formation (Ladinian-Carnian boundary), representing one of the oldest “silesaurids” worldwide. Furthermore, Gondwanax paraisensis gen. et sp. nov is the oldest “silesaurid” with three sacral vertebrae, a feature usually observed in more derived forms. In addition, distinct from any other Triassic Pan-Aves, the new taxon bears an incipient fourth trochanter of the femur. This unique combination of features indicates a high diversity of locomotor strategies among early pan-avians. In addition, the co-occurrence of Gondwanax paraisensis gen. et sp. nov. and Gamatavus antiquus in the same Assemblage Zone represents the oldest evidence of sympatry among “silesaurids” in South America. Indeed, the unique combination of sacral and hindlimb features may suggest distinct behaviors for these species, potentially leading to niche differentiation within the same ecosystems.

LINK(S)

https://www.sciencedirect.com/science/article/abs/pii/S1342937X24002764

ABSTRACT

The Lower to Middle Jurassic Kota Formation of India has yielded abundant yet disarticulated skeletal remains attributed to the basally diverging sauropod Kotasaurus yamanpalliensis. The hypodigm of Kotasaurus yamanpalliensis includes four ellipsoidal elements that we identify as tail clubs, based on morphological similarities to tail clubs attributed to two basal sauropods from China: Shunosaurus lii, for which a fully articulated tail series was recovered, and Omeisaurus tianfuensis. Detailed comparison of the Chinese and Indian tail clubs suggests that they are composed of up to three individual elements that fuse in adulthood. Computed tomography of the Indian tail clubs reveals their internal structure, which shows incremental growth lines as well as other features whose origin and function remain unknown. The Indian and Chinese tail clubs share a similar temporal range (Early to Middle Jurassic) and similar morphologies, which raises the question of whether sauropod tail clubs evolved once, multiple times, or were gained and then lost within basally diverging members of Sauropoda. We describe four new characters to reflect the morphological constituents of sauropod tail clubs known to date.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2396814

ABSTRACT

The end of the Cretaceous saw the Western Interior Seaway divide North America into two land masses, Laramidia in the west and Appalachia in the east. Laramidian dinosaurs inhabited a narrow strip of land extending from Mexico to Alaska. Within this geographically restricted area, dinosaurs evolved high diversity and endemism, with distinct species in the north and south. Here, we report a new tyrannosaurid from the Late Campanian-aged Cerro del Pueblo Formation of Coahuila, Mexico, which is part of a tribe of tyrannosaurs originating in southern Laramidia. Phylogenetic analysis recovers the new tyrannosaur as part of a clade including Labocania anomala from the La Bocana Roja Formation of Baja California Norte, Bistahieversor sealeyi from the Kirtland Formation of New Mexico, Teratophoneus curriei from the Kaiparowits Formation in Utah, and Dynamoterror dynastes from the Menefee Formation of New Mexico. Distinct frontal morphology and the younger age (~72.5–73 Ma versus >75.8 Ma for L. anomala) support recognition of the new tyrannosaur as a distinct species of Labocania, Labocania aguillonae. The Labocania clade dominated southern Laramidia at a time when the north was dominated by daspletosaurins and albertosaurines. The high endemism seen in tyrannosaurids is remarkable, given that modern apex predators have large geographic ranges and hints that the diversity of carnivorous dinosaurs has been underestimated.

LINK(S)

https://www.mdpi.com/2813-6284/2/4/12?fbclid=IwY2xjawFg7idleHRuA2FlbQIxMQABHcoiRJokBF2E-DpeGG20wJdQVETaKSl7o0dlN7nUhmepb1RXKSzf6udlUw_aem_GBuKhuzgwO4V5wL3c43bpg

ABSTRACT

Forelimb bones of the Jurassic theropod Allosaurus fragilis were digitally manipulated based on three-dimensional (3D) digital models. Bony articular surface margins were used as limits to determine the range of motion (ROM) for each forelimb joint, and to test functional hypotheses of forelimb usage. We discuss the effects of palaeopathology at the right shoulder joint on inferring ROM in the forelimb of Allosaurus. It is considered that the glenoid aberration of this sub-adult specimen occurred in early ontogeny and lasted for a long period of time, affecting to varying degrees the development of the whole right arm (but not the manus). The relatively large ranges of extension and flexion of manual joints indicate well grasping ability consistent with early-diverging theropods. The limited ROM of the shoulder joints of Allosaurus suggests that the forelimbs were predominantly prey-acquiring but could go no further forward, indicating that the first contact with prey was made by the mouth. The manus could assist in grasping prey on the chest or below the neck or hooking objects.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2403599

ABSTRACT

Reports of cannibalistic behavior in fossil muricids are scarce and are only known from the Quaternary. This study presents evidence of cannibalism among Crassimurex (s. s.) calcitrapa (Lamarck, 1803), from the Lutetian of the Paris Basin (France). The studied material comes from the quarry of La Ferme de l’Orme (Yvelines, France) and was collected in a unit (unit 6) in which this species is the lone drilling predator. The paleoenvironment of this bed corresponds to intertidal or shallow subtidal brackish facies and C. (s. s.) calcitrapa is associated with an assemblage containing other euryhaline species. The samples collected include 132 specimens, among which 14 display predatory holes attributed to conspecifics, thus suggesting cannibalism. Small specimens between 2-7 mm are the most commonly drilled and the size of drill holes indicates that juveniles as well as adults are responsible of these attacks. We also observed a global selection of drilling sites that are well oriented to the weak points of the shell (between the varices and avoiding the spines). Finally, this study shows that behaviors such as predation on juveniles, selection of weak parts of the shell and multiple drill holes on the same prey are similar to Quaternary and extant cases. The precise conditions leading to cannibalism are difficult to highlight, but subtidal brackish facies are accompanied by many environmental stressors that can promote opportunistic behaviors such as occasional cannibalism. Also, the sudden appearance of cohorts of hatchlings adds to these stressors.

LINK(S)

https://sciencepress.mnhn.fr/en/periodiques/geodiversitas/46/13

ABSTRACT

In this paper, we describe a new ophthalmosaurid specimen found in the lower Barremian beds of the Paja Formation at Villa de Leiva, Boyacá, Colombia. The specimen represents a new species of Platypterygius, P. elsuntuoso sp. nov. defined by three unique features within the genus: a small ventral peg in the anterior ventral border of the extracondylar area of the basioccipital; a supratemporal groove in the quadrate; and a shallow neck at the base of the acellular cementum ring on the teeth root. In support of our taxonomic determination, in this contribution we also assess the species composition of the genus Platypterygius, comparing the known anatomy of the type species P. platydactylus with that of the other species previously assigned to the genus. We found that a great morphological affinity in the forelimb of the species P. americanus, P. australis, P. hercynicus, and P. sachicarum (lower Barremian to lower Cenomanian) with that of the type species (Aptian) is unquestionable and differentiate them from all other ophthalmosaurids. Three new diagnostic features (synapomorphies of the genus) support their inclusion in Platypterygius. Consequently, the genus name “Kyhytysuka”, recently proposed to differentiate P. sachicarum from the genus Platypterygius is here rejected. A careful comparison of the cranial characteristics of Platypterygius specimens preserving associated cranial and fin remains demonstrate that Platypterygius is a genus distinguishable from other ophthalmosaurids not only by a typical forelimb but also by a particular combination of skull features. In this context, the skull morphology of “Simbirskiasaurus” concurs with that defining Platypterygius and its minor differences are not sufficient to support its generic distinction. The morphological comparisons and our phylogenetic analysis show the new species P. elsuntuoso more closely related to the Colombian species P. sachicarum than to other species of Platypterygius. Given that the new species came from the lower Barremian and P. sachicarum came from the upper Barremian, the minor differences in dentition found between the two species suggest a speciation by adaptation to new food sources in the Cretaceous epicontinental sea of Colombia.

LINK(S)

https://revistas.unal.edu.co/index.php/esrj/article/view/112332

https://revistas.unal.edu.co/index.php/esrj/article/view/112332/93137

ABSTRACT

The renowned Late Miocene locality of Maragheh (northwest Iran) has yielded ample material of chalicotheres, most of which has never been described in detail. The present study concerns the taxonomic evaluation of this material and its attribution to the large schizotheriine Ancylotherium pentelicum. This allows a detailed comparison to schizotheriine material from other localities, and based on this, we provide an overview of the diagnostic features of Ancylotherium that separate it from all other chalicotheres. This improves our understanding of the type species A. pentelicum. Additionally, we discuss the palaeobiogeography of the species, which is best known from the Balkan Peninsula. Maragheh marks the easternmost occurrence of A. pentelicum, but its presence has even been suggested in Africa. Lastly, we discuss the existence of sexual size dimorphism in the species, based on the herein described material along with previously described specimens of A. pentelicum from other fossil sites, such as the famous Late Miocene localities Pikermi and Samos (Greece). Specifically, it is shown that many postcranial elements exhibit great size variability that is most probably associated with significant sexual dimorphism.

LINK(S)

https://link.springer.com/article/10.1007/s10914-024-09730-7
https://link.springer.com/content/pdf/10.1007/s10914-024-09730-7.pdf

ABSTRACT

A juvenile pachycephalosaur frontal from the upper Aguja Formation (Late Cretaceous: middle Campanian) of West Texas, USA is unusually thin dorsoventrally, even compared to ‘flat’ frontals of young individuals pertaining to other pachycephalosaur taxa. The specimen is most comparable morphologically and morphometrically to Stegoceras validum. However, it is much thinner than any ‘juvenile’ example of that species, and also differs in the elongate form and radial arrangement of the surficial tubercles, as well as occurrence of radial grooves along the lateral margins of the bone. Such differences are unlikely a reflection of intraspecific variation. Instead, the Aguja specimen likely represents a previously unknown juvenile semaphoront from the southern Western Interior, referred herein to Stegoceras sp. and likely extends the distribution of this widespread Campanian genus. A morphometric evaluation suggests that the holotype specimen of Texacephale langstoni, also from the Aguja Formation, is probably an adult semaphoront of Stegoceras. However, both specimens represent different ontogenetic stages with dissimilar morphologies and so their potential conspecifity remains equivocal. The new Aguja specimen described herein likely represents a ‘paedomorphic’ Campanian pachycephalosaur – one where the onset of doming is displaced until well into ontogeny – a heterochronic attribute Stegoceras sp. shares with S. validum and Pachycephalosaurus wyomingensis. Where an adequate ontogenetic sample is available for comparison, other pachycephalosaur taxa do not seem to exhibit a similar growth progression, and so this appears to be a significant taxonomic characteristic. That some pachycephalosaurs delayed doming of the skull roof during growth is enigmatic, but it may have been an expression of sexual dimorphism, an aid in species recognition, or a response to harsh environmental conditions.

LINK(S)

https://www.sciencedirect.com/science/article/abs/pii/S0016699524000767

ABSTRACT

Chaohusaurus is an early ichthyosauriform represented by three species known from the Early Triassic of Chaohu, Anhui Province, China, with a fourth species—Chaohusaurus zhangjiawanensis—known from the Nanzhang-Yuan’an region of Hubei Province. In contrast to the Chaohusaurus species from Chaohu, Chaohusaurus zhangjiawanensis remains poorly known, hindering our understanding of early ichthyosauriform evolution. Here, we report a new specimen of Chaohusaurus zhangjiawanensis, which provides new information on its dentition. The new specimen confirms that Chaohusaurus zhangjiawanensis had heterodont dentition consisting of pointed anterior teeth and robust, rounded posterior teeth, indicating a generalist diet. The posterior teeth of Chaohusaurus zhangjiawanensis are more robust (broader and larger) than the posterior dentition of Chaohusaurus chaoxianensis and Chaohusaurus brevifemoralis from Chaohu. This suggests differences in hard-shelled prey preference between species of Chaohusaurus from Chaohu and Nanzhang-Yuan’an, with Chaohusaurus zhangjiawanensis likely capable of feeding on harder and larger prey than Chaohusaurus brevifemoralis and Chaohusaurus chaoxianensis. In turn, this probably reflects differences in durophagous prey availability between the shallow-marine palaeoecosystem of Nanzhang-Yuan’an and the deeper, slope-basin palaeoecosystem of Chaohu. The posterior dentition and forefin of Chaohusaurus zhangjiawanensis are strikingly similar to those of Chaohusaurus geishanensis, the rarest species of Chaohusaurus from the Chaohu fauna. The scarcity of Chaohusaurus geishanensis in the Chaohu fauna, and its morphological similarity to Chaohusaurus zhangjiawanensis, possibly indicate that Chaohusaurus geishanensis was closely related with Chaohusaurus zhangjiawanensis and that it was also a shallow-marine species that was not a typical component of the Chaohu fauna. It probably occasionally wandered out into the deeper waters of Chaohu from a nearby coastal environment.

LINK(S)

https://sjpp.springeropen.com/articles/10.1186/s13358-024-00331-8
https://sjpp.springeropen.com/counter/pdf/10.1186/s13358-024-00331-8.pdf

ABSTRACT

The Horned Serpent panel at La Belle France (Free State Province, South Africa) was painted by the San at least two hundred years ago. It pictures, among many other elements, a tusked animal with a head that resembles that of a dicynodont, the fossils of which are abundant and conspicuous in the Karoo Basin. This picture also seemingly relates to a local San myth about large animals that once roamed southern Africa and are now extinct. This suggests the existence of a San geomyth about dicynodonts. Here, the La Belle France site has been visited, the existence of the painted tusked animal is confirmed, and the presence of tetrapod fossils in its immediate vicinity is supported. Altogether, they suggest a case of indigenous palaeontology. The painting is dated between 1821 and 1835, or older, making it at least ten years older than the formal scientific description of the first dicynodont, Dicynodon lacerticeps, in 1845. The painting of a dicynodont by the San would also suggest that they integrated (at least some) fossils into their belief system.

LINK(S)

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0309908

ABSTRACT

The turtle shell is a remarkable structure that has intrigued not only evolutionary biologists but also engineering and material scientists because of its multi-scale complexity and various functions. Although protection is its most apparent role, the carapace and plastron are also related to many physiological functions and their shape influences hydrodynamics and self-righting ability. As such, analysing the functional morphology of the shell could help understanding the ecology of Triassic stem-turtles, which will contribute to the century-long debate on the evolutionary origins of turtles. Here, we used 3D imaging techniques to digitize the shells of two of the earliest stem-turtle taxa, Proganochelys and Proterochersis, and submitted their models to biomechanical and shape analyses. We analysed the strength performance under five predation scenarios and tested the function of two morphological traits found in stem-turtles, the epiplastral processes and an attached pelvic girdle. The latter, also present in the crown-lineage of side-necked turtles, has been suggested to increase load-bearing capacity of the shell or to improve swimming in pleurodires. Our results do not confirm the shell-strengthening hypothesis and, together with the results of our shape analyses, suggest that at least one of the first stem-turtles (Proterochersis) was an aquatic animal.

LINK(S)

https://www.nature.com/articles/s41598-024-72540-7
https://www.nature.com/articles/s41598-024-72540-7.pdf

ABSTRACT

Modern poriferans are classified into four classes—Calcarea, Demospongiae, Hexactinellida and Homoscleromorpha—the recognition of which in fossil specimens almost exclusively relies on spicule morphology and arrangement. Early fossil representatives of the phylum Porifera are morphologically diverse, and many of them problematically display characteristics that are incompatible with the classification scheme developed for modern taxa. Critically, hexactine spicules—a diagnostic feature of hexactinellids among modern taxa—are found in various Cambrian and Ordovician taxa that cannot be accommodated within the hexactinellid body plan. Here we describe a new poriferan from the Drumian Marjum Formation of Utah, Polygoniella turrelli gen. et sp. nov., which exhibits a unique combination of complex anatomical features for a Cambrian form, including a syconoid-like organization, a thick body wall, and a multi-layered hexactin-based skeleton. The hexactinellid-like body wall architecture of this new species supports a Cambrian origin of the hexactinellid body plan and provides valuable insights into character evolution in early glass sponges.

LINK(S)

https://royalsocietypublishing.org/doi/10.1098/rsos.231845

ABSTRACT

Among the available palaeopathological results on non-avian dinosaurs, the fracture is the most documented category. Therein, only two sauropod fractured cases have been reported, and no sauropod tibial fracture has been mentioned. In this study, we report a special sauropod tibial fracture from the Middle Jurassic of Yunyang County, Chongqing, southwest China. The morphological observation shows a planar-shaped sauropod tibial fracture, with a rough surface without fracture callus, and does not exhibit other healing manifestations such as swelling. The CT images and energy spectrum data clearly demonstrate the injured cortical bone invaginated into the medullary cavity. Moreover, these data indicate that the tibia fracture is initial, the first valid record of initial fracture in non-avian dinosaurs. This study enhances our knowledge of sauropod limb bone fractures and enriches the pathological information about dinosaur fractures.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2403598

ABSTRACT

Styracosternan ornithopods are plenty abundant in the Lower Cretaceous fossil record of Europe. In particular, Iguanodon, the second genus of dinosaurs described worldwide, has been found in UK, Belgium, France, Germany, and Spain, evidencing a wide geographical distribution. Currently, the genus Iguanodon comprises two species, the type species I. bernissartensis from the late Barremian–Aptian of Europe and I. galvensis from the early Barremian of Teruel, Spain. The latter species is well known mainly from perinate and juvenile specimens. Here, axial and appendicular fossils of an adult, large and massively constructed ornithopod from the lower Barremian (Lower Cretaceous) Camarillas Formation of Galve (province of Teruel, Spain) are described. Fossil dimensions and some osteological evidence reveal that the specimen was a large (roughly 10 m long) ornithopod. An autapomorphic feature in the ischium and other characters allow us to ascribe this specimen to I. galvensis. In addition, postcranial co-ossification and fusion of the neurocentral suture indicate that the specimen was skeletally mature. Part of the material studied here was unknown in adults of I. galvensis, providing a better knowledge of the axial and appendicular region of this species.

LINK(S)

https://www.mdpi.com/1424-2818/16/9/586

ABSTRACT

To date, soft-tissue remains of extinct incirrate octopods have been described exclusively from Upper Cretaceous deposits. Here, three specimens of an incirrate octopodid with well-preserved soft tissue imprints are described for the first time from Paleogene strata. This material originates from the upper Ypresian (lower Eocene) fish-bearing levels of the Bolca Konservat-Lagerstätte in the Pesciara of Bolca in north-eastern Italy. Previously, these specimens had tentatively been interpreted as teuthids. Based on a detailed study of their anatomical structure, a new genus and species of octopodid, Bolcaoctopus pesciaraensis, belonging to the extant family Octopodidae, are here erected. Bolcaoctopus gen. nov. may be distinguished from the Late Cretaceous genus Styletoctopus by the presence of long and thin arms and an elongated body shape with a narrowed apical end and covered by longitudinal wrinkles. Although finds of fossil octopuses in the Bolca Konservat-Lagerstätte remain extremely rare, it is worth noting that Cenozoic marine vertebrate localities constitute an important potential source of additional finds of coleoid cephalopods, the study of which may shed light on a poorly understood period in the evolutionary history of these molluscs.

LINK(S)

https://riviste.unimi.it/index.php/RIPS/article/view/23207
https://riviste.unimi.it/index.php/RIPS/article/view/23207/22109

ABSTRACT

Palynological data obtained from sediments that include the first find of a tusk fragment of the Trogontherii elephant (Mammuthus trogontherii) in Primorskii krai allowed us to reconstruct its living environment in the Middle Pleistocene. The reconstructed plant formations indicate warmer and drier climatic conditions during the existence of Mammuthus trogontherii in the southern part of the Russian Far East than the modern conditions. The ecosystems of the region had a more complex structure. Nemoral plants were more widely represented in them. Mesophilic pine–spruce forests with broadleaf trees and larch–birch sparse forests were the main feature of landscapes. Shrubby birch and alder thickets, sparse larch-birch forests, and sphagnum mires occupied plains and lakeshores.

LINK(S)

https://link.springer.com/article/10.1134/S1028334X24603523

ABSTRACT

The colonization of the pelagic realm by the vertebrates represents one of the major transitions in the evolutionary success of the group and in the establishment of modern complex marine ecosystem. It has been traditionally related with the Devonian rise of jawed vertebrates, but new evidences indicate that first active swimmers, invading the water column, occurred within earlier armoured jawless fishes (“ostracoderms”). These “primitive” fishes lacked conventional fish control surfaces and the precise mechanism used to generate lift and stabilizing forces still remains unclear. We show that, because of their shape, the rigid cephalic shield of Pteraspidiformes, a group of Silurian-Devonian “ostracoderms”, generate significant forces for hydrodynamic lift. Particle Image Velocimetry and force measurements in a water channel shows that the flow over real-sized Pteraspidiformes models is similar to that over delta wings, dominated by the formation of leading-edge vortices resulting in enhanced vortex lift forces and delayed stall angles of attack. Additionally, experiments simulating ground effect show that Pteraspidiformes present better hydrodynamic performance under fully pelagic conditions than in a benthic scenario. This suggests that, lacking movable appendages other than the caudal fin, leading-edge vortices were exploited by earliest vertebrates to colonize the water column more than 400 Mya.

LINK(S)

https://www.nature.com/articles/s42003-024-06837-8

https://www.nature.com/articles/s42003-024-06837-8.pdf

ABSTRACT

A partial caudal fin of a large-bodied asthenocormine pachycormiform (Pachycormiformes: Pachycormidae: Asthenocorminae) is described from the Upper Jurassic (lower Tithonian) Kimmeridge Clay Formation of Dorset, England. The specimen comprises associated fin rays, basal fulcra, ‘epurals’ and paired pre-caudal scutes, the combination and morphology of which is consistent with the large (2–3 m TL) edentulous, supposedly ‘suspension-feeding’ asthenocormine, Asthenocormus titanius (Wagner), presently known only from the Upper Jurassic plattenkalks of Bavaria, Germany. Asthenocormus has previously been documented in the literature as being present in the Middle and Upper Jurassic of England, however all of these specimens have been misattributed or since referred to different genera. However, the specimen from the Kimmeridge Clay Formation is here referred with confidence to Asthenocormus. Morphological variation in the pre-caudal dorsal scute of the new specimen compared to the Bavarian material suggest that the Kimmeridge Clay specimen likely represents a new species of Asthenocormus, although it is currently too poorly represented to diagnose, and hence we refer the specimen to Asthenocormus cf. titanius. The new specimen represents the first true record of Asthenocormus from the UK, thereby extending its known palaeobiogeographic distribution and further demonstrating faunal similarities between fish assemblage from the Kimmeridge Clay Formation of Dorset and the Solnhofen-type plattenkalks of southern Germany. Additional comments are also made on the hidden diversity of pachycormid fishes in the Kimmeridge Clay Formation.

LINK(S)

https://link.springer.com/article/10.1007/s12542-024-00700-1

https://link.springer.com/content/pdf/10.1007/s12542-024-00700-1.pdf

ABSTRACT

Unexpectedly abundant remains of herbivorous therapsids in the Late Triassic strata of southern Poland have significantly supplemented knowledge of their evolution. The skeletal morphology of the Late Norian (or Rhaetian) dicynodont Lisowicia bojani supports its close relationship to the Carnian Woznikella, both known from the Polish part of the Germanic Basin. Three evolutionary lineages of dicynodonts—Laurasian–Gondwanan Rhadiodromus klimovi → Jachaleria candelariensis lineage, Laurasian lineage Shaanbeikannemeyeria xilougouensis → Lisowicia bojani, and the Gondwanan lineage Kannemeyeria simocephalus → Dinodontosaurus brevirostris—are distinguished based on characters of cranial and postcranial elements. In the lineages characterized by the parietal oval in cross-section and the two distinct articulations on the sternum, there is a tendency to exclude the frontal from the orbital margin and to reduce the number of sacral vertebrae. In the lineage with the parietal narrow and triangular in cross-section, the frontal forms part of the orbit margin, there is a single joint on the sternum, and there is a tendency towards flattening the skull roof. In both lineages the shoulder girdle is convergently modified, the acromion process decreased, and joints on the sternum moved posteriorly.

LINK(S)

https://academic.oup.com/zoolinnean/article-abstract/202/1/zlae085/7758256

ABSTRACT

A theropod ilium MHNM KK04 from the Kem Kem Beds (Cenomanian) of Morocco was originally described as an abelisaurid. It is here reinterpreted as a spinosaurine spinosaurid. The phylogenetic relationships of MHNM KK04 were analyzed. A thorough and careful comparison between spinosaurids and abelisaurids was made. The Kem Kem ilium was identified as a spinosaurid based on the similarity to the Spinosaurus aegyptiacus neotype and the MSNM V6900 specimen (i.e., the lateral wall of brevis fossa is taller than the medial wall, the ventral margin of the postacetabular blade is straight, and the ventral margin of postacetabular process is posteroventrally oriented). However, MHNM KK04 is slightly different from the ilium of the Spinosaurus aegyptiacus neotype (i.e., the ilium dorsal margin is sub-horizontal to slightly anteriorly inclined, the dorsoventral height of the iliac blade at the postacetabular portion is approximately the same size as the blade height above the acetabulum, and the postacetabulum length is slightly longer than the ischial peduncle length). MHNM KK04, together with previous studies, shows that there were at least two morphotypes of spinosaurines in the Late Cretaceous of Kem Kem beds. Nevertheless, taphonomy, intraspecific or ontogenetic variation cannot be ruled out in the present work. This reclassification adds to the number of juvenile spinosaurines from the Kem Kem beds and provided evidence on the evolution of ilia in spinosaurids.

LINK(S)

https://www.sciencedirect.com/science/article/abs/pii/S0195667124001800

ABSTRACT

The fossil record of Upper Cretaceous fishes in Colombia is particularly scarce, with only eleven previously identified species. This study presents the first comprehensive report of the extinct aulopiform fish family Enchodontidae from the Eastern Cordillera of Colombia. Fieldwork in the municipality of Matanza (Santander Department) yielded five fossil specimens, including jaw and skull fragments. These specimens were collected from the Upper Cretaceous La Luna Formation and were described and examined to approximate their taxonomic affinity, depositional environment, and geological age. Detailed morphological analyses associate these new specimens with the genus Enchodus. Our findings provide new data that contribute to the understanding of Enchodus diversity and distribution. The presence of key diagnostic characters in our specimens aligns with established phylogenetic frameworks, while further highlighting the potential for the presence of new species within this record.

LINK(S)

https://www.sciencedirect.com/science/article/abs/pii/S0895981124003821

ABSTRACT

All large planets in our Solar System have rings, and it has been suggested that Mars may have had a ring in the past. This raises the question of whether Earth also had a ring in the past. Here, we examine the paleolatitudes of 21 asteroid impact craters from an anomalous ∼40 m.y. period of enhanced meteor impact cratering known as the Ordovician impact spike, and find that all craters fall in an equatorial band at ≤30°, despite ∼70 % of exposed, potentially crater-preserving crust lying outside this band. The beginning of this period is marked by a large increase in L chondrite material accumulated in sedimentary rocks at 465.76 ± 0.30 Ma, which, together with the impact spike, has long been suggested to result from break-up of the L chondrite parent body in the asteroid belt. Our binomial probability calculation indicates that it is highly unlikely that the observed crater distribution was produced by bolides on orbits directly from the asteroid belt (P = 4 × 10–8). We therefore propose that instead, a large fragment of the L chondrite parent body broke up due to tidal forces during a near-miss encounter with the Earth at ∼466 Ma. Given the longevity of the impact spike and sediment-hosted L chondrite debris accumulation, we suggest that a debris ring formed after this break up event, from which material deorbited to produce the observed crater distribution. We further speculate that shading of Earth by this ring may have triggered cooling into the Hirnantian global icehouse period.

LINK(S)

https://www.sciencedirect.com/science/article/pii/S0012821X24004230

ABSTRACT

Head segments play a critical role in revealing the relationships within major arthropod groups but the accurate determination of their number and relationship is challenging because of the decoupling of dorsal tergites and ventral appendages. In recent decades, trilobites have been considered to have four pairs of cephalic appendages and, commonly, five dorsal segments, which has served as the basis for understanding euarthropod cephalic evolution. Based on multiple analytical techniques applied to well-preserved soft-bodied specimens of the Upper Ordovician olenid Triarthrus eatoni and middle Cambrian corynexochid Olenoides serratus, we argue that an additional pair of cephalic biramous appendages occurred just behind the antennae, indicating that trilobites had five pairs of cephalic appendages and six dorsally expressed segments. We propose that the mismatch between the four dorsal furrows and five ventral appendages in Olenoides may be reconciled by considering the morphology of the hypostome that marks the position of the antenna and the bifurcation of the first glabellar furrow that has two muscle attachment sites fused. The fusion of clustered attachment sites of the cephalic biramous appendages may have aided feeding ability by gathering the limb bases close to the mouth.

LINK(S)

https://onlinelibrary.wiley.com/doi/10.1111/pala.12723

ABSTRACT

The living coelacanth Latimeria (Sarcopterygii: Actinistia) is an iconic, so-called ‘living fossil’ within one of the most apparently morphologically conservative vertebrate groups. We describe a new, 3-D preserved coelacanth from the Late Devonian Gogo Formation in Western Australia. We assemble a comprehensive analysis of the group to assess the phylogeny, evolutionary rates, and morphological disparity of all coelacanths. We reveal a major shift in morphological disparity between Devonian and post-Devonian coelacanths. The newly described fossil fish fills a critical transitional stage in coelacanth disparity and evolution. Since the mid-Cretaceous, discrete character changes (representing major morphological innovations) have essentially ceased, while meristic and continuous characters have continued to evolve within coelacanths. Considering a range of putative environmental drivers, tectonic activity best explains variation in the rates of coelacanth evolution.

LINK(S)

https://www.nature.com/articles/s41467-024-51238-4

https://www.nature.com/articles/s41467-024-51238-4.pdf

ABSTRACT

Understanding the extent to which tyrannosaurid cranial morphology changed through ontogeny is essential to correctly refer tyrannosaurid specimens at varying life stages to taxa. However, taxonomically diagnostic immature tyrannosaurid bones remain exceedingly elusive. Over the last century the University of Alberta has collected three isolated immature cranial bones referable to Daspletosaurus from Dinosaur Provincial Park, Alberta of Treaty 7 Territory. These bones were all collected from the rocks of the Dinosaur Park Formation and include a premaxilla (UALVP 48717), jugal (UALVP 61561), and lacrimal (UALVP 47955). To assess the taxonomic utility of these bones, they were compared to tyrannosaurid material from the Dinosaur Park and Oldman Formations of Alberta. This provided an opportunity to examine size-independent discrete characters in tyrannosaurid crania. The results of this study suggest that many premaxillary, jugal, and lacrimal discrete characteristics observed in Daspletosaurus are constrained throughout ontogeny. A single ontogenetically invariant character, the dorsal flange of the palatal process, was identified for Daspletosaurus premaxillae. Ontogenetically invariant characters of the jugal include, but are not limited to, a medial lacrimal slot, and the lateral fossa on the postorbital process. Invariant lacrimal characters include an anteroposteriorly short pneumatic recess opening and a subdivided nasal articulation fossa on the medial surface of the bone. The identification of these characters allows specimens of the tyrannosaurine Daspletosaurus and the contemporaneous albertosaurine Gorgosaurus to be confidently identified regardless of ontogenetic stage. These characters were applied to a controversial tyrannosaurid specimen from the Dinosaur Park Formation (TMP 1994.143.0001) resulting in referral to G. libratus, rather than Daspletosaurus sp.

LINK(S)

https://cdnsciencepub.com/doi/10.1139/cjes-2024-0083?fbclid=IwY2xjawFQHpxleHRuA2FlbQIxMQABHeBJM8UZoRz20yUG_mX4ru3K2D4mMMi3FmX_yz3nuJdAF52byxlSjY3PUw_aem_nU3gDtmtQ-m2YET6gQqgag

ABSTRACT

Diet is one of the most important aspects of an animal’s ecology, as it reflects direct interactions with other organisms and shapes morphology, behavior, and other life history traits. Modern birds (Neornithes) have a highly efficient and phenotypically plastic digestive system, allowing them to utilize diverse trophic resources, and digestive function has been put forth as a factor in the selectivity of the end-Cretaceous mass extinction, in which only neornithine dinosaurs survived. Although diet is directly documented in several early-diverging avian lineages, only a single specimen preserves evidence of diet in Enantiornithes, the dominant group of terrestrial Cretaceous birds. Morphology-based predictions suggest enantiornithines were faunivores, although the absence of evidence contrasts with the high preservation potential and relatively longer gut-retention times of these diets. Longipteryx is an unusual Early Cretaceous enantiornithine with an elongate rostrum; distally restricted dentition; large, recurved, and crenulated teeth; and tooth enamel much thicker than other paravians. Statistical analysis of rostral length, body size, and tooth morphology predicts Longipteryx was primarily insectivorous. Contrasting with these results, two new specimens of Longipteryx preserve gymnosperm seeds within the abdominal cavity interpreted as ingesta. Like Jeholornis, their unmacerated preservation and the absence of gastroliths indicate frugivory. As in Neornithes, complex diets driven by the elevated energetic demands imposed by flight, secondary rostral functions, and phylogenetic influence impede the use of morphological proxies to predict diet in early-diverging avian lineages.

LINK(S)

https://www.cell.com/current-biology/fulltext/S0960-9822(24)01124-2

https://www.cell.com/cms/10.1016/j.cub.2024.08.012/attachment/7947cd1d-8268-43c5-a485-796d42a17bbd/mmc2.pdf

ABSTRACT

Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996 was originally described on the basis of a single complete fossil specimen excavated near Besano (Italy). However, a recent taxonomic revision and re-examination of the cranial osteology allowed for the assignment of five additional specimens to the taxon. Here, we analyse, describe and discuss the postcranial anatomy of Besanosaurus leptorhynchus in detail. The size of the specimens examined herein ranged from slightly more than one meter to eight meters. Overall, several diagnostic character states for this taxon are proposed, demonstrating a mosaic of plesiomorphic and derived features. This is best exemplified by the limbs, which show very rounded elements in the forelimbs, and pedal phalanges with retained rudimentary shafts. We suggest that the widely spaced phalanges in the forefins of Besanosaurus leptorhynchus were embedded in a fibrocartilage-rich connective tissue, like in modern cetaceans. We also review the similarities of Besanosaurus with Pessopteryx and Pessosaurus, allowing us to conclude that Besanosaurus is not a junior synonym of either of the two taxa. Lastly, to test the swimming capabilities of Besanosaurus leptorhynchus, we expanded on a previously published study focussing on reconstructing the swimming styles of ichthyosaurs. Besanosaurus leptorhynchus was found to possess a peculiar locomotory mode, somewhat intermediate between anguilliform swimmers, such as Cymbospondylus and Utatsusaurus, and some shastasaur-grade (e.g., Guizhouichthyosaurus) and early-diverging euichthyosaurian (e.g., Californosaurus) ichthyosaurs. Based on our results, we furthermore suggest that mixosaurids acquired their characteristic body profile (dorsal fin and forefins that are distinctly enlarged compared to the hindfins) independently and convergently to the one that later appeared in Parvipelvia. Moreover, the different swimming styles inferred for Cymbospondylus, Mixosauridae, and Besanosaurus strengthen the earlier hypothesis of niche partitioning among these three distinct ichthyosaur taxa from the Besano Formation.

LINK(S)

https://sjpp.springeropen.com/articles/10.1186/s13358-024-00330-9

https://sjpp.springeropen.com/counter/pdf/10.1186/s13358-024-00330-9.pdf

ABSTRACT

Much of what we know about terrestrial life during the Carboniferous Period comes from Middle Pennsylvanian (~315–307 Mya) Coal Measures deposited in low-lying wetland environments. We know relatively little about terrestrial ecosystems from the Early Pennsylvanian, which was a critical interval for the diversification of insects, arachnids, tetrapods, and seed plants. Here we report a diverse Early Pennsylvanian trace and body fossil Lagerstätte (~320–318 Mya) from the Wamsutta Formation of eastern North America, distinct from coal-bearing deposits, preserved in clastic substrates within basin margin conglomerates. The exceptionally preserved trace fossils and body fossils document a range of vertebrates, invertebrates and plant taxa (n = 131), with 83 distinct foliage morphotypes. Plant-insect interactions include what may be the earliest evidence of insect oviposition. This site expands our knowledge of early terrestrial ecosystems and organismal interactions and provides ground truth for future phylogenetic reconstructions of key plant, arthropod, and vertebrate groups.

LINK(S)

https://www.nature.com/articles/s41467-024-52181-0
https://www.nature.com/articles/s41467-024-52181-0.pdf

ABSTRACT

Bonebeds, concentrations of fossilized vertebrates, provide valuable insights into paleoecological, biostratigraphic, and macroevolutionary contexts, though they are often influenced by taphonomic processes. Brazilian Triassic rocks are notable for such fossil assemblages. Among these, the Várzea do Agudo site is remarkable for its abundance of fossils of the traversodontidae cynodont Exaeretodon riograndensis. Initial studies suggested that biogenic factors, especially scavenging and predation, were key to the formation of these bonebeds. This study aims to describe a new fossiliferous concentration from this site, analyzing the taphonomic and biostratinomic processes involved in its genesis. Our findings indicate that multiple factors, including biogenic actions and environmental conditions such as floodplain dynamics, contributed to the accumulation and preservation of the abundant bonebeds. This integrative approach enhances our understanding of the paleoecology of Exaeretodon riograndensis, which was probably a gregarious animal, and the environmental context of Hyperodapedon Assemblage Zone.

LINK(S)

https://www.sciencedirect.com/science/article/pii/S089598112400364X

ABSTRACT

Biomechanical studies in sauropod dinosaurs are mainly focused on neck posture and feeding strategy. Few works investigate other aspects such as tail movement and function, especially in the clade Titanosauria, the most diverse within Neosauropoda. This study applied biomechanical concepts of neutral pose (cartilaginous neutral pose) and range of motion to verify the shape and direction of the caudal region of the advanced titanosaurs Adamantisaurus mezzalirai and Baurutitan britoi, in addition to comparing it with other titanosaurs (e.g., Arrudatitan maximus, Lirainosaurus astibiae, and Trigonosaurus pricei). As a result, the tails analyzed have a sigmoidal-convex shape, probably close to the ground (but not touching it). The sigmoidal-convex shape could increase the moment arm for the M. caudofemoralis longus, making it possible to use the tail as a fifth stabilizing member. This work expands our knowledge about sauropod dinosaurs by exposing a diversity of shapes for the tails of titanosaur sauropods and brings new possibilities for how these dinosaurs could use their tails.

LINK(S)

https://onlinelibrary.wiley.com/doi/abs/10.1111/joa.14134

ABSTRACT

An exceptional a hypertrophic batoid rostrum of exceptional size (TL = 1460 mm) and four fragmentary rostral teeth collected from the marine Maastrichtian of the Dakhla Formation, Egypt. Both the macroscopic aspects (with the presence of a "wood-like" layer that covers the central part of the rostrum and the presence of skin denticles at the bases of the ventral face) and microscopic characters (presence of tessellated cartilage in the central part of the rostrum and of laminated cartilage in the peripheral areas of it) demonstrate that the rostrum belongs to a large specimen of the genus Onchopristis Stromer, 1917 . The absence of complete rostral teeth prevents the establishment of a new species. Nonetheless, the described finds demonstrate, for the first time, that the genus Onchopristis persisted in the euryhaline areas of North Africa until the end of the Cretaceous.

LINK(S)

https://www.sciencedirect.com/science/article/pii/S1464343X24002486?via%3Dihub

ABSTRACT

Dunkleosteus is a widely-recognized prehistoric organism, yet its life appearance, paleobiology, and even basic morphology remain poorly understood. A new reconstruction of D. terrelli is presented here based on examination of complete, three-dimensionally mounted dermal skeletons and a review of available paleontological evidence. Despite the post-thoracic body of D. terrelli being poorly known, its morphology and body shape can be constrained based on preserved elements and conserved anatomical patterns seen both within arthrodires and across fishes more broadly. Trunk armor proportions, estimated body length, and the locations of the fin bases suggest D. terrelli had a relatively stout, deep trunk. Its trunk armor is apomorphically deep among arthrodires, resulting in a body shape reminiscent of other pelagic vertebrates (lamnids, thunnins, ichthyosaurs). The anterior trunk is stiffened due to the interlocking ventral shield plates and fused spine restricting lateral motion, and its anatomy suggests extremely large lateral trunk muscles and a well-developed horizontal septum, compatible with thunniform swimming. Body depth is positively allometric in D. terrelli, resembling other arthrodires. Eubrachythoracid arthrodires likely had incomplete lateral lines. The pectoral fin base of Dunkleosteus is located at an extreme anterior position on the body, and the pelvic girdle is unusually small. Arthrodires appear more disparate in body shape than previously assumed, and many taxa may have been well-adapted to active nektonic life, though their rigid dermal armor and generally stocky bodies imply swimming kinematics unlike most living fishes. Many questions about their biology and biomechanics remain unanswered, representing ideal targets for future research.

LINK(S)

https://palaeo-electronica.org/content/current-in-press-articles/5307-dunkleosteus-reconstruction
https://palaeo-electronica.org/content/pdfs/1343.pdf

ABSTRACT

New thylacinid species of Badjcinus, Nimbacinus, and Ngamalacinus are described from upper Oligocene deposits of the Riversleigh World Heritage Area, northwestern Queensland. Badjcinus timfaulkneri, Nimbacinus peterbridgei, and Ngamalacinus nigelmarveni are among the oldest thylacinids yet known and indicate an earlier diversification of the family than previously understood. Maximum parsimony analysis supports a sister group relationship between Ng. nigelmarveni and Ng. timmulvaneyi, but the relationships of the two other new taxa are unresolved. Bayesian dated total evidence analysis using morphological and molecular data supports the generic assignment of B. timfaulkneri and Ng. nigelmarveni but not that of Ni. peterbridgei. Both phylogenies herein support a taxonomic reassignment of Thylacinus macknessi to the genus Wabulacinus, a conclusion also supported by the results of previous studies. Body mass estimates based on molar size regressions indicate body sizes ranging from 3.7 kg to 11.4 kg for the new thylacinid species. Badjcinus timfaulkneri exhibits an extremely deep jaw compared with other thylacinids, with mandibular bending strength analysis suggesting that it was a highly durophagous carnivore much like the modern dasyurid Sarcophilus harrisii. This analysis also suggests Ni. peterbridgei had a dentary more similar in shape to that of plesiomorphic thylacinid faunivores such as Ni. dicksoni and T. cynocephalus suggesting that it had a relatively more generalist faunivorous diet. The molars of Ng. nigelmarveni suggest they were better suited for longitudinal slicing than the molars of B. timfaulkneri and Ni. peterbridgei, indicating a more hypercarnivorous diet compared with that of those species.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2384595

ABSTRACT

Biarmosuchia, the most basal therapsid clade, is represented by relatively few specimens known from Permian deposits in Russia and southern Africa. In both the Guadalupian (middle Permian) and Lopingian (late Permian), biarmosuchians represent less than 1% of the fossil record at the specimen level. Here, we describe a new burnetiamorph biarmosuchian, Impumlophantsi boonstrai, based on a partial skull and associated postcrania from the upper Tapinocephalus Assemblage Zone. It is characterized by the presence of a low nasal crest with a unique morphology among burnetiamorphs. Inclusion of this taxon in an updated phylogenetic analysis of biarmosuchians indicates that this specimen is one of the most basal burnetiamorphs, representing the only record of this grade from the middle Permian.

LINK(S)

https://wiredspace.wits.ac.za/items/b1b057e4-2f95-4764-9035-bbc5a78be2cc

https://wiredspace.wits.ac.za/server/api/core/bitstreams/5d73e2ab-2efd-4d12-bac8-dd748913b199/content

ABSTRACT

Pterosaurs were the earliest and largest vertebrates to evolve powered flight, but they are the only major volant group that has gone extinct. Attempts to understand pterosaur flight mechanics have relied on aerodynamic principles and analogy with extant birds and bats. Both lines of inquiry rely on the size, three-dimensional shape, and internal structure of flight bones, which in pterosaurs are surprisingly rare. Remarkably, two new large-bodied pterosaur individuals with three-dimensionally preserved wing elements were recently recovered from Upper Cretaceous (Maastrichtian) horizons of Jordan. Both specimens represent azhdarchoid pterosaurs; one is referrable to the giant species Arambourgiania philadelphiae (ca. 10 m wingspan) and the second to a new, smaller species Inabtanin alarabia gen. et sp. nov. (ca. 5 m wingspan). In this study, we describe these new specimens and use high-resolution micro-computed tomography scans to reconstruct and compare the internal osteology of the humeri of these two differently sized species to that of extant birds, for which internal bone structure can be correlated with flight behavior. The humerus of Arambourgiania exhibits a series of helical ridges formed along the cortical bone, whereas Inabtanin exhibits a denser pattern of hollow struts. Variation in internal structure for these individuals likely reflects responses to mechanical forces applied on the wings of pterosaurs. Results indicate that Inabtanin has internal bone morphology similar to that of flapping birds, whereas the internal morphology of Arambourgiania is most similar to that of soaring birds.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2385068

ABSTRACT

Paleoneurological studies of mosasaurids are few and limited to old partial reconstructions made from latex casts on Platecarpus and Clidastes. Here, the brain endocasts of three specimens of the early mosasaurid Tethysaurus nopcsai from the Turonian of Morocco are reconstructed for the first time by using micro-computed tomography. Comparisons between Tethysaurus and the later Platecarpus and Clidastes show that distinct endocranial organizations have occurred within the clade through time, including differences in the flexure of the endocast and the size of the parietal eye. The physiological consequences of such variability remain unclear and further investigations are required to better interpret these variations. In addition, the endocast of Tethysaurus was compared to those of extant anguimorphs, iguanians, and snakes, using landmark-based geometric morphometrics. The results revealed that Tethysaurus exhibits a unique combination of endocranial features compared to extant toxicoferans. Contrary to previous statements, we find no strong resemblance in endocast morphology between Tethysaurus and varanids. Rather, the endocast of Tethysaurus shows some morphological similarities with each of the clades of anguimorphs, iguanians, and snakes. In this context, while a notable phylogenetic signal is observed in the variability of squamate endocasts, it is premature to establish any phylogenetic affinities between mosasaurids and extant squamates based solely on endocast morphologies.

LINK(S)

https://www.mdpi.com/1424-2818/16/9/548

ABSTRACT

Microbial communities are important components controlling the fidelity of fossil fish preservation. The Eocene Green River Formation lagerstätten, exceptionally preserved fossil deposits, provides an opportunity to examine the role of microbial communities and their metabolic byproducts, such as chemical precipitated in this spectacularly preserved fish deposit, famous throughout the world. Field emission scanning electron microscope (FESEM) and energy dispersive spectroscopy system (EDS) examination of a well-preserved Knightia eocaena from the Eocene Green River Formation documents the presence of bacteriomorphs. Bacteriomorphs in a sample from the Fossil Butte Member of the Green River Formation consists of spherical structures, coccoid-type bacteria, fibres from two-sized populations of filamentous bacteria, probable filamentous cyanobacteria, capsule-shaped, and bacilliform bacteria, all associated with framboidal iron hydroxide.

Bacteriomorphs consist of external molds composed of nanometer-scale calcium carbonate spheres. Fe-oxide framboids have an amorphous exterior and a sieve-like internal structure. The sieve-like structure consists of nanometer-scale pores, probable sites of bacterial cells with walls composed of 100-nanometer-scale spheres. Fe-oxides are consistent with bacterially mediated precipitation of pyrite followed by an oxidation event. Preserved bacteriomorphs are consistent with degradation of soft tissue, limiting the preservation of soft tissue and leaving bone and scales with no appreciable soft tissue. The microfossils are restricted to the skeleton and are not found in the surrounding rock matrix, suggesting larger microbial mats may not have been present and possibly did not have a significant impact on the preservation of this specimen.

LINK(S)

https://link.springer.com/article/10.1007/s12549-024-00621-6

https://link.springer.com/content/pdf/10.1007/s12549-024-00621-6.pdf

ABSTRACT

A new lithostrotian titanosaur, Qunkasaura pintiquiniestra gen. et sp. nov., is described based on a single partial skeleton from the late Campanian-early Maastrichtian fossil-site of Lo Hueco (Cuenca, Spain). This new taxon is supported by an exclusive combination of characters that highlights strong convergences with members of the South American Aeolosaurini. Qunkasaura allows to reorganise the complex phylogenetic relationships of the increasingly diverse finicretaceous sauropods of Europe. Phylogenetic analyses places Qunkasaura within Saltasauridae and possibly Opisthocoelicaudiinae, together with Abditosaurus. A new clade is established, Lohuecosauria, including Saltasaurus, Lohuecotitan, their most recent common ancestor and all its descendants. Two distinct Ibero-Armorican Campanian-Maastrichtian saltasauroid lineages are recognised: (i) Lirainosaurinae that is exclusive from Europe, and (ii) a saltasaurid lineage with possible opisthocoelicaudiine affinities, with a Laurasian distribution. Lirainosaurinae was a relict lineage including possible dwarf forms that evolved in isolation after reaching Europe before the Late Cretaceous through the Apulian route. The occurrence of opisthocoelicaudiines in Europe may be the result of a Late Cretaceous interchange between Europe and Asia. No evidence of insular dwarfism is found in the Ibero-Armorican opisthocoelicaudiines suggesting that they may have been newcomers to the area that arrived before the ‘Maastrichtian Dinosaur Turnover’ in southwestern Europe.

LINK(S)

https://www.nature.com/articles/s42003-024-06653-0

https://www.nature.com/articles/s42003-024-06653-0.pdf

ABSTRACT

The herbivorous dinosaur clade Ceratopsia flourished in the northern hemisphere during the Late Jurassic to Late Cretaceous. Previous palaeobiogeographic studies have suggested that their initial diversification occurred in Asia, with early-branching neoceratopsians extending their geographical range to North America sometime during the Barremian to Albian. However, the specific timing and mode of their dispersal from Asia to North America remains unknown. Here we describe a new, early-branching neoceratopsian, Sasayamagnomus saegusai gen. et sp. nov., from the Albian Ohyamashimo Formation in southwestern Japan, representing the easternmost fossil record of ceratopsians in Asia. Sasayamagnomus exhibits three diagnostic features in the jugal, squamosal and coracoid, respectively, and also has a unique combination of characters in the lacrimal. Our phylogenetic analysis indicates that Sasayamagnomus forms a clade with Aquilops americanus, one of the earliest neoceratopsians from North America, followed by the sister taxon Auroraceratops rugosus from China. The present time-calibrated phylogenetic tree indicates that the immigration of neoceratopsians from Asia to North America occurred during the latest Aptian or early Albian, refining the previously suggested timeframe. This aligns with fragmentary neoceratopsian fossil records from the Lower Cretaceous of North America and the initial formation of the Bering land bridge. Furthermore, the simultaneous occurrence of global warming (which enabled the development of extensive forests in the Arctic region) and the emergence of the Bering land bridge during the Aptian–Albian, probably played a crucial role in facilitating the immigration of neoceratopsians from Asia to North America.

LINK(S)

https://onlinelibrary.wiley.com/doi/abs/10.1002/spp2.1587

ABSTRACT

Previous studies arguing for parental care in dinosaurs have been primarily based on fossil accumulations of adults and hatchlings, perinatal and post-hatchlings in nests and nest areas, and evidence of brooding, the majority of which date to the Late Cretaceous. Similarly, the general body proportions of preserved embryonic skeletons of the much older Early Jurassic Massospondylus have been used to suggest that hatchlings were unable to forage for themselves. Here, we approach the question of parental care in dinosaurs by using a combined morphological, chemical, and biomechanical approach to compare early embryonic and hatchling bones of the Early Jurassic sauropodomorph Lufengosaurus with those of extant avian taxa with known levels of parental care. We compare femora, the main weight-bearing limb bone, at various embryonic and post-embryonic stages in a precocious and an altricial extant avian dinosaur with those of embryonic and hatchling Lufengosaurus, and find that the rate and degree of bone development in Lufengosaurus is closer to that of the highly altricial Columba (pigeon) than the precocious Gallus (chicken), providing strong support for the hypothesis that Lufengosaurus was fully altricial. We suggest that the limb bones of Lufengosaurus hatchlings were not strong enough to forage for themselves and would likely need parental feeding.

LINK(S)

https://www.nature.com/articles/s41598-024-70981-8

https://www.nature.com/articles/s41598-024-70981-8.pdf

ABSTRACT

The Late Cretaceous of Western North America (Laramidia) supported a diverse dinosaur fauna, with duckbilled dinosaurs (Hadrosauridae) being among the most speciose and abundant members of this assemblage. Historically, collecting and preservational biases have meant that dinosaurs from Mexico and the American Southwest are poorly known compared to those of the northern Great Plains. However, evidence increasingly suggests that distinct species and clades inhabited southern Laramidia. Here, a new kritosaurin hadrosaurid, represented by the anterior part of a skull, is reported from the late Campanian of the Cerro del Pueblo Formation, ~72.5 Ma, in Coahuila, Mexico. The Cerro del Pueblo Formation kritosaur was originally considered to represent the same species as a saurolophine from the Olmos Formation of Sabinas, but the Sabinas hadrosaur is now considered a distinct taxon. More recently, the Cerro del Pueblo Formation kritosaur has been referred to Kritosaurus navajovius. We show it represents a new species related to Gryposaurus. The new species is distinguished by its large size, the shape of the premaxillary nasal process, the strongly downturned dentary, and massive denticles on the premaxilla’s palatal surface, supporting recognition of a new taxon, Coahuilasaurus lipani. The dinosaur assemblage of the Cerro del Pueblo Formation shows higher diversity than the contemporaneous fauna of the Horseshoe Canyon Formation in Alberta. Furthermore, Kritosaurini, Lambeosaurini, and Parasaurolophini all persist into the latest Campanian in southern Laramidia after disappearing from northern Laramidia. These patterns suggest declining herbivore diversity seen at high latitudes may be a local, rather than global phenomenon, perhaps driven by cooling at high latitudes in the Late Campanian and Maastrichtian.

LINK(S)

https://www.mdpi.com/1424-2818/16/9/531