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Our knowledge of vertebrate functional evolution depends on inferences about joint function in extinct taxa. Without rigorous criteria for evaluating joint articulation, however, such analyses risk misleading reconstructions of vertebrate animal motion. Here we propose an approach for synthesizing raycast-based measurements of 3-D articular overlap, symmetry, and congruence into a quantitative "articulation score" for any non-interpenetrating six-degree-of-freedom joint configuration. We apply our methodology to bicondylar hindlimb joints of two extant dinosaurs (guineafowl, emu) and, through comparison with in vivo kinematics, find that locomotor joint poses consistently have high articulation scores. We then exploit this relationship to constrain reconstruction of a pedal walking stride cycle for the extinct dinosaur Deinonychus antirrhopus, demonstrating the utility of our approach. As joint articulation is investigated in more living animals, the framework we establish here can be expanded to accommodate additional joints and clades, facilitating improved understanding of vertebrate animal motion and its evolution. Criteria for evaluating joint articulation in vertebrates are lacking. Here, the authors propose an approach for combining measurements of 3D articular overlap, symmetry, and congruence into a single metric, and apply this to examine the walking stride of Deinonychus antirrhopus. [ABSTRACT FROM AUTHOR]

• New caenagnathid specimens are described from the Late Cretaceous of West Texas. • Most complete caenagnathids known from the southern Western Interior. • Adds new comparative material representing the scant 'southern' caenagnathid record. • Osteohistology and phylogeny helps resolve caeanagnathid dinosaur affinities. • The work represents a vital 'southern' dinosaur paleofaunal datum for North America. New caenagnathid dinosaur specimens from the upper Aguja Formation of West Texas comprise the most complete examples yet described from southern North America. Two individuals are represented. Osteohistology indicates that both were mature at their times of death. Although they share no overlapping elements, the two individuals are separated by overall body size, paleohabitat, and stratigraphic position and so they almost certainly represent different species. One individual consists of a partial hindlimb, but exhibits too few (3) characters to be phylogenetically informative and is, therefore, referred to an indeterminate caenagnathid – possibly one of two species previously recognized in coastal facies of the Aguja Formation. The second individual is more complete. It was recovered higher in section from more inland fluvial paleoenvironments and preserves fragmentary elements from throughout the postcranial skeleton. A histology-based growth model – the first for a caenagnathid – indicates that the second individual required at least five years to approach fully adult size. However, only 11 character states could be derived from its preserved remains. Phylogenetic analyses found this specimen deeply nested within Caenagnathidae, but were otherwise inconclusive and so it, too, is referred to an indeterminate caenagnathid. Nevertheless, several combined morphologies (e.g., absence of cervical epipophyses, dorsoventral depth of the hypapophysis on the second cervicodorsal vertebra, and greater trochanter of the femur only weakly separated from the femoral head) implies that the second individual represents an unknown species. One critical aspect of both specimens is that they provide significant new comparative material representing the sparse 'southern' caenagnathid record. [ABSTRACT FROM AUTHOR]

A newly discovered dinosaur tracksite in the Middle Jurassic Xietan Formation of the Zigui Basin, is the first reported from Hubei Province, China. Access to the site is difficult due to the steep inclination (~60°) of the track-bearing beds. The tracks are poorly preserved and occur in a fragmented mudstone substrate. However, it is possible to identify a sauropod trackway and isolated tridactyl (theropod) tracks, suggesting a saurischian dominated ichnofauna. The preserved sauropod trackway falls into the range of a typical wide gauge sequence and, together with the overall shape of the imprints and low heteropody, points to the ichnogenus Brontopodus. The tracks are of relatively small size and can possibly be attributed to juveniles of a large species or, alternatively, to adults of a small species of eusauropods. The tridactyl tracks are incomplete and cannot be assigned to a distinct ichnotaxon with certainty. [ABSTRACT FROM AUTHOR]

The clinical appearance and radiological pattern of osteoarthritis have been identified in the skeletons of dinosaurs some 50–70 million years old, and in Egyptian mummies, and in ancient skeletons in England. Osteoarthritis patterns of joint involvement, often referred to as primary osteoarthritis, can be seen in the hands, spinal facet joints, hips, knees and feet, but can also be termed secondary osteoarthritis when seen in any joint that has had trauma, sepsis, surgery or metabolic insult. The prevalence of osteoarthritis increases with age. The histology and pathophysiology both demonstrate an inflammatory process. While there have been studies of genetic predisposition, the basic cause of primary osteoarthritis has not been determined. [ABSTRACT FROM AUTHOR]

The Nanushuk Formation (Albian–Cenomanian) crops out over much of the central and western North Slope of Alaska, varying from ≈1500 to ≈250 m thick from west to northeast. The Nanushuk Formation records an inter-tonguing succession of marine and nonmarine conglomerate, sandstone, mudstone, and coal. These rock units comprise the Kukpowruk and Corwin formations of the former Nanushuk Group, respectively. Work presented here is centered in the foothills of the DeLong Mountains along the Kukpowruk River, from an area west of Igloo Mountain in the Coke Basin to the Barabara Syncline, approximately 80 km to the north. A radiometric date recovered from a tuff in our study area suggests a Cenomanian age for at least some of these rocks. Outcrops along the Kukpowruk River contain a well-preserved fossil flora previously recovered from marine, marginal marine, and terrestrial sediments. Our own work focuses on detailed measured sections of terrestrial rocks, interpretation of sedimentary facies and facies associations, and documentation of fossil vertebrates. Eight facies associations are identified in the study area that together are interpreted to represent meandering fluvial and upper delta plain environments. Plant fossils are common and include standing tree trunks up to 58 cm in diameter at some locations. Approximately 75 newly discovered tracksites, and a heretofore unknown, rich fossil vertebrate ichnofauna, are present. The ichnofaunal assemblage includes evidence of small and large theropod dinosaurs (including birds) and bipedal and quadrupedal ornithischian dinosaurs. Approximately 15% of the dinosaur ichnofauna record is represented by fossil bird tracks. Wood fragments from the Nanushuk Formation were analyzed for their carbon isotopic composition to relate δ13C to mean annual precipitation. Samples averaged −26.4‰ VPDB, suggesting an average MAP of 1412 mm/year. This record of increased precipitation in the Nanushuk Fm. during the mid-Cretaceous provides new data that supports global precipitation patterns associated with the Cretaceous Thermal Maximum. This work provides an important framework for much-needed further paleoecological and paleoclimatic analyses into greenhouse conditions in the terrestrial Cretaceous Arctic during this important window in time. [ABSTRACT FROM AUTHOR]

Caenagnathidae is a clade of derived, Late Cretaceous oviraptorosaurian theropods from Asia and North America. Because their remains are rare and often fragmentary, caenagnathid diversity is poorly understood. Anzu wyliei is the only caenagnathid species currently described from the late Maastrichtian Hell Creek Formation of the USA and is also among the largest and most completely preserved North American caenagnathids. Smaller, less complete caenagnathid material has long been known from the Hell Creek Formation, but it is unclear whether these are juvenile representatives of Anzu or if they represent distinct, unnamed taxa. Here, we describe a relatively small caenagnathid hindlimb from the Hell Creek Formation, and conduct osteohistological analysis to assess its maturity. Histological data and morphological differences from Anzu wyliei and other caenagnathids allow us to conclude that this specimen represents a new species of caenagnathid from the Hell Creek Formation, with a smaller adult body size than Anzu. This new taxon is also distinct from other small caenagnathid material previously described from the area, potentially indicating the coexistence of three distinct caenagnathid species in the Hell Creek Formation. These results show that caenagnathid diversity in the Hell Creek ecosystem has been underestimated. [ABSTRACT FROM AUTHOR]

Teeth evolved early in vertebrate evolution, and their morphology reflects important specializations in diet and ecology among species. The toothless jaws (edentulism) in extant birds likely coevolved with beak keratin, which functionally replaced teeth. However, extinct dinosaurs lost teeth multiple times independently and exhibited great variation in toothrow distribution and rhamphotheca-like keratin structures. Here, we use rostral jawbone surface texture as a proxy for rostral keratin covering and phylogenetic comparative models to test for the influence of rostral keratin on toothrow distribution in Mesozoic dinosaurs. We find that the evolution of rostral keratin covering explains partial toothrow reduction but not jaw toothlessness. Toothrow reduction preceded the evolution of rostral keratin cover in theropods. Non-theropod dinosaurs evolved continuous toothrows despite evolving rostral keratin covers (e.g. some ornithischians and sauropodomorphs). We also show that rostral keratin covers did not significantly increase the evolutionary rate of tooth loss, which further delineates the antagonistic relationship between these structures. Our results suggest that the evolution of rostral keratin had a limited effect on suppressing tooth development. Independent changes in jaw development may have facilitated further tooth loss. Furthermore, the evolution of strong chemical digestion, a gizzard, and a dietary shift to omnivory or herbivory likely alleviated selective pressures for tooth development. [ABSTRACT FROM AUTHOR]

Rebbachisauridae is a clade of sauropod dinosaurs whose maximum diversification and abundance are known from the Cretaceous of South America. We describe an anterior caudal vertebra, MDPA-Pv 007, from the Upper Cretaceous of Argentine Patagonia, whose characters allow it to be referred to this clade. Also, two phylogenetic analyses reinforce the referral of the new material more exclusively to Rebbachisaurinae. We analyze pneumatic structures using the first CT scans of a caudal element of a rebbachisaurid. The excellent preservation of MDPA-Pv 007, combined with CT images, allows us to document external fossae and foramina that connect to larger internal chambers, constituting unambiguous evidence of pneumaticity. The centrum of MDPA-Pv 007 is camerate, with large interconnected internal chambers; this is accompanied by a neural arch with wide and deep fossae. Caudal pneumaticity has a complex phylogenetic distribution among neosauropods. This feature may have evolved independently in diplodocoids and titanosauriforms, or it could be ancestral for Neosauropoda but secondarily lost in a few lineages. Future investigations, taking advantage of new technologies, will provide insights into the phylogenetic distribution and paleobiological implications of pneumaticity in sauropod dinosaurs and other fossil archosaurs. [ABSTRACT FROM AUTHOR]

The continental Lower Triassic (Middle Buntsandstein) siliciclastic deposits exposed along the margins of the Holy Cross Mountains, Poland, yield locally abundant vertebrate footprints and bones. Although the footprints have been described in a number of studies, providing, for example, new insights into the origin of dinosaurs, there are few studies focusing on the bones. Here, we describe new amphibian and reptile material from the Buntsandstein fluvial sandstones of early Olenekian age exposed at Stryczowice on the north-eastern margin of the Holy Cross Mountains. These finds include fragmentary cranial specimens referred to as Trematosauridae gen. et sp. indet. and Procolophonidae gen. et sp. indet. Faunal differences between Stryczowice and the best-known Polish Olenekian vertebrate-bearing site of Czatkowice 1 near Kraków support heterogeneity in the Early Triassic vertebrate distribution across Pangea. [ABSTRACT FROM AUTHOR]

The evolution and biodiversity of ageing have long fascinated scientists and the public alike. While mammals, including long‐lived species such as humans, show a marked ageing process, some species of reptiles and amphibians exhibit very slow and even the absence of ageing phenotypes. How can reptiles and other vertebrates age slower than mammals? Herein, I propose that evolving during the rule of the dinosaurs left a lasting legacy in mammals. For over 100 million years when dinosaurs were the dominant predators, mammals were generally small, nocturnal, and short‐lived. My hypothesis is that such a long evolutionary pressure on early mammals for rapid reproduction led to the loss or inactivation of genes and pathways associated with long life. I call this the 'longevity bottleneck hypothesis', which is further supported by the absence in mammals of regenerative traits. Although mammals, such as humans, can evolve long lifespans, they do so under constraints dating to the dinosaur era. [ABSTRACT FROM AUTHOR]

Here, we describe a pathological sub-adult theropod dinosaur from the Late Jurassic Morrison Formation in Dana Quarry, Wyoming, U.S.A. It exhibits multiple pathologies, involving three dorsal vertebrae, the right scapula and coracoid, and apparent pathology of the left scapula. The fourth dorsal vertebra has four irregularly shaped growths on the vertebral arch. The eighth and ninth vertebrae are fused. The scapulocoracoid joint has an obvious deformity. The distal part of the right scapula is more rounded than normal. The left scapula has a depression on the lateral blade. These pathologies can be identified as follows: the fourth dorsal vertebra is possibly neoplastic or exhibiting compensatory hyperplasia; the eighth and ninth vertebral and the right scapular pathology are consistent with spondyloarthropathy. Diagnoses considered for the left scapula pathology are infections, trauma or unknown. The animal survived the pathologies, which are unlikely the cause of its death. This specimen represents the first known occurrence of spondyloarthropathy in a theropod. [ABSTRACT FROM AUTHOR]

Principal Component Analysis (PCA) is a powerful statistical technique for reducing the complexity of data and making patterns and relationships within the data more easily understandable. By using PCA, students can learn to identify the most important features of a data set, visualize relationships between variables, and make informed decisions based on the data. As such, PCA can be an effective tool to increase students data literacy by providing a visual and intuitive way to understand and work with data. This article outlines a teaching strategy to introduce and explain PCA using basic mathematics and statistics together with visual demonstrations. [ABSTRACT FROM AUTHOR]

Turiasauria is a clade of basal sauropod dinosaurs hitherto only known from the Middle Jurassic (Bathonian) to the Lower Cretaceous (Valanginian). A new find of a shed tooth crown from the Lower Jurassic (Pliensbachian), Halse Formation of Bornholm, Denmark, is spoon-like, asymmetrical, and heart-shaped, which identifies the tooth as turiasaurian, pushing the origin of the Turiasauria some 17 My back into the Lower Jurassic. This suggests a North Pangean/Laurasian origin of the turiasaurian clade, which then, during the Middle to Late Jurassic, dispersed through Europe, India, and Africa, with their latest representatives found in the Early Cretaceous of England and North America. Furthermore, this is the first record of a sauropod from the Pliensbachian in Europe. [ABSTRACT FROM AUTHOR]

The idea that birds are maniraptoran theropod dinosaurs is now considered an evolutionary consensus. An "open" (i.e., completely or substantially perforate) acetabulum is considered an important synapomorphy verifying the bird–dinosaur nexus. Here, I present anatomical evidence from the acetabulum and its important appurtenances, the supracetabular crest and the antitrochanter, that hip anatomy differs substantially between dinosaurs and birds. Given the thin bone of the acetabular walls and the varied tissue, both hard and soft, in the acetabular region and especially the lower part of the basin, it is apparent that many avian skeletons exhibit some anatomical loss of soft tissue and thin bone, some perhaps related to changes in gait, but also in part related to the dramatic trend in bone reduction associated with flight, especially in more advanced crown taxa. Many basal birds and early diverging neornithines tend to have a nearly closed or partially closed acetabula, thus rendering the current terms "open" or "closed" acetabula inaccurate; they should be modified or replaced. Given new evidence presented here, the relationship of "dinosaurs" and birds must be re-evaluated. [ABSTRACT FROM AUTHOR]

Adaptation to specialist ecological niches is a key innovation that has contributed to the evolutionary success of many vertebrate clades, underpinning the acquisition of diverse skull morphologies. Dinosaurs, which dominated Mesozoic terrestrial faunas, acquired herbivory multiple times, and evolution of these herbivorous adaptations is linked to drastic changes in dental and craniomandibular functional morphology, yet whether changes in functionally relevant phenotypic traits occurred more rapidly in herbivorous lineages compared to in carnivorous lineages remains largely untested in a statistical phylogenetic framework. Here, we infer rates of phenotypic evolution using phylogenetic variable‐rate models on relative biting edge (tooth row) lengths of 107 dinosaur taxa to test the hypothesis that the acquisition of herbivory is associated with rapid changes in mandibular biomechanics. We find elevated rates of biomechanical evolution in theropods with foreshortened and beaked skulls (Oviraptorosauria, Limusaurus), as well as in ceratopsians and Diplodocus. The presence and position of a reduced tooth row and increased jaw efficiency unite these high‐rate lineages, indicating selection for greater efficiency in biting biomechanics. Large departures from the isometric scaling of these mandibular characteristics helps explain the differences in evolutionary rates in these clades and those of other herbivorous theropods (Therizinosauria, Ornithomimosauria). Additionally, we hypothesize that extreme ontogenetic changes within species lifetimes may be behind some instances of branch‐wise elevated rates. Thus, we show how exceptional rates of biomechanical evolution can reveal signatures of ecological adaptations within dinosaur lineages as well as within‐species ontogenetic sequences. [ABSTRACT FROM AUTHOR]

Nematode worms are the most abundant multicellular organism on Earth. They thrive in every habitat known, and they are voracious feeders within the top 70 cm of soils. Their sturdy cuticle protects them from environmental factors and predators. Nematodes play a significant role in the decomposition of vertebrate remains in soil and serve as indicators of nutrients that enter soils during decomposition. Certain parasitic nematodes have been identified in fossil remains, but reports of fossil worms are rare. We demonstrate the abundant presence of opportunistic nematodes feeding within dinosaur bones from the Hell Creek formation, MT. The presence of visible worm ultrastructure indicates that they were alive when preserved within the dinosaur bones. Our findings are identical to worms characterized as "blood parasites" in a dinosaur bone from Brazil, demonstrating that there is sufficient soft tissue within dinosaur bone canals to sustain large populations of nematodes post-mortem. [ABSTRACT FROM AUTHOR]

Over the past decades, abundant and wellpreserved vertebrate fossils, known as the Urho Pterosaur Fauna, have been recovered from the Lower Cretaceous Tugulu Group in Junggar Basin, Xinjiang, NW China. Excavated materials belong to pterosaur, plesiosaur, dinosaur, crocodylomorph, and turtle taxa. As such, they provide key insights into the evolutionary history of several critical vertebrate groups in the Early Cretaceous. The Junggar assemblages have been interpreted as belonging to the Jehol Biota sensu lato, representing its northwesternmost known geographic extent. This research presents a new chemical abrasion--isotope dilution--thermal ionization mass spectrometry U-Pb age of 135.2 ± 0.9 Ma (2σ internal error) from a tuffaceous bed stratigraphically below the fauna-bearing layers, indicating a Valanginian maximum age for the Urho fauna. Combined with available biostratigraphic data, the results bear several important paleobiologic implications for the Early Cretaceous vertebrates. First, the Dsungaripterus pterosaur and Psittacosaurus ornithischian fauna appear to have emerged earlier than previously believed. Second, the data suggest that the oldest carcharodontosaurids in Asia appeared during the Valanginian Stage and extend the age range of basal coelurosaurs and basal crocodyliforms. Our results do not support the notion of the Jehol Biota sensu lato migrating as far west as the Junggar Basin in their later stages. The new information calls into question the temporal and spatial bases for the conventional, threestage evolutionary theory of the Jehol Biota. [ABSTRACT FROM AUTHOR]

Endocranial cavities preserve a record of neural anatomy often used for hypotheses of behavior in extinct organisms. Two reconstructions of cranial endocasts of Allosaurus fragilis and A. jimmadseni from computed tomography data expand understanding of theropod endocranial anatomy including endocranial volume, inner ear shape, and trigeminal ganglion size. Endocranial and trigeminal ganglion volumes are compared with a sample of birds, crocodylians, and non-avian theropod dinosaurs. Allosaurus is found to have a relatively small trigeminal foramen for its body size when compared with foramina of birds and crocodylians. The inner ear is fragmentary but similar in shape to semicircular canals of other large-bodied theropod dinosaurs. These findings suggest Allosaurus had generalist neural structures relative to other non-avian theropod dinosaurs. Like other large-bodied theropod dinosaurs, Allosaurus likely had a large dural venous sinus, potentially important for brain cooling. Allosaurus did not have a derived sense of facial somatosensation akin to that found in crocodylians or some birds. Additional data like these, collected from other tetanuran dinosaurs, will help clarify the evolution of neurosensory systems in the lineage. [ABSTRACT FROM AUTHOR]

The posterior portion of a sturgeon skull preserved in a nodule was recovered from the latest Campanian sediments of the Horseshoe Canyon Formation in the city of Edmonton, Alberta, Canada. It is described here as a new genus and species of Acipenseriformes. The skull represents an individual of at least 2 meters in total length. This species is of particular interest because different bones of the skull show a surface ornamentation with different patterns; the clavicle has large pits, the dermal skull bones have smaller pits and radiating ridges, and the subopercle shows fine radiating ridges. The new taxon, here named †Boreiosturion labyrinthicus, can be confidently included in the extant family Acipenseridae but a phylogenetic analysis does not further resolve relationships. This fossil is the first documentation of sturgeon in the latest Campanian of North America, and bridges the gap between the mid-Campanian assemblage of Dinosaur Park and the late Maastrichtian material from the Hell Creek Formation. [ABSTRACT FROM AUTHOR]

New specimens and the reassessment of many silesaurids have recently shed light on the origin and early evolution of dinosaurs and their close relatives. Yet, the group is relatively poorly represented in South America, an area that likely played an important role in dinosaurian origins. Since the discovery of Sacisaurus agudoensis from the Norian Caturrita Formation, only the fragmentary Gamatavus antiquus and Amanasaurus nesbitti have been reported from the Triassic of south Brazil. Here we describe disarticulated silesaurid remains from Waldsanga, one of the most important tetrapod-bearing localities of the Santa Maria Formation, which represent the second Carnian occurrence of the group in Brazil. The postcranial elements exhibit a combination of dinosauromorph symplesiomorphies and silesaurid diagnostic traits, showing that a conservative anatomy is pervasive among early dinosauromorphs. We also conducted a set of exploratory analyses to infer the phylogenetic relations of the new occurrence and the robustness of some of the most recent phylogenetic hypotheses in face of the increasing diversity of Silesauridae. This revealed a rather uncertain evolutionary scenario not only for Silesauridae, but for early dinosauromorphs in general. [ABSTRACT FROM AUTHOR]

In some rural areas, the impact of palaeontological research on dinosaurs and their geological environment is a very important scientific, cultural, and socio-economic catalyst. The proliferation of places that showcase these types of resources (such as palaeontological parks, museums, geoparks, interpretation centres, and guided routes, etc.) has multiplied in recent years, and they are visited by thousands of people interested in the history of life on Earth. Spain is one of the most representative countries in the world regarding the use of dinosaurs as a factor for territorial development in rural areas. In some cases, such as in the province of Teruel, this is enhanced by the permanent presence of specialists who carry out their research in the immediate environment from which the fossils originate. [ABSTRACT FROM AUTHOR]

Over the past 20 years, the study of fossils using 3D visualisation techniques, better known as virtual palaeontology, has revolutionised the study of organisms from the past. The study of the popular sauropod dinosaurs is a clear example: the complex mounting systems or expensive replicas once used to study their skeletons are now easily achievable thanks to advances in computing. Thus, questions such as the position of their long necks, their movement capabilities and functional implications, or even how they mated, are easier to address than ever before. Therefore, the insights gained through traditional methods, together with the contributions of new technologies, are opening up new frontiers in the study of these titans. [ABSTRACT FROM AUTHOR]

The Maestrat Basin, in the Iberian Range, has proved to be a key point for the study of the hadrosauriform dinosaurs of the Lower Cretaceous in Europe. The Aliaga, Galve, and Morella sub-basins have all yielded abundant fossils of Mesozoic vertebrates, among which dinosaurs, and especially hadrosauriform styracosternan ornithopods, are the most abundant group from these areas. In this article, we review recent findings in the Maestrat Basin, which suggest that the diversity of this clade during the Barremian-Albian interval was greater than originally thought, providing us with valuable information for the study and understanding of the evolution of these dinosaurs. [ABSTRACT FROM AUTHOR]

The article focuses on the evolution of public perception regarding dinosaurs, shifting from pure entertainment to a deeper understanding of their geological and biological significance. Topics include common questions in paleontology about dinosaur sites, their size, color, and mysteries, alongside the legacy of large-scale productions and museum exhibitions that have both fueled public curiosity and advanced scientific research in dinosaurology.

The first discovery of any dinosaur remains in a US National Park Service unit in Alaska occurred in 2001 in Aniakchak National Monument and Preserve. The record consisted of the track of a pes impression, or track made by the foot of a hadrosaur (duck-billed dinosaur) and an associated manus impression, or track made by a hand. Subsequent work has shown the original track discovery was not unique, and that the coastal exposures of the Cretaceous Chignik Formation in Aniakchak National Monument and Preserve contain a remarkable number of tracks. Further, because of the limited faulting, the several hundred meters of section found along this coastal set of exposures provide a remarkably complete look at an ancient high-latitude dinosaurian ecosystem and are of outstanding universal value. [ABSTRACT FROM AUTHOR]

Dinosaur National Monument was established in 1915 to protect and preserve the globally significant paleontological resources of the Carnegie Dinosaur Quarry. The park was expanded in 1938 and now protects 210,844.02 acres in northeastern Utah and northwestern Colorado. Extensive inventory, monitoring, excavation, and research work has taken place in the monument, mostly focusing on the Late Jurassic-age Morrison Formation over the past 113 years since the Carnegie Quarry's discovery in 1909. This work has helped to increase not only our knowledge of the dinosaur fauna, but also of the less well-known reptiles, amphibians, mammals, invertebrates, and plant communities that lived alongside these Jurassic giants. To protect and preserve these notable fossil discoveries, Dinosaur National Monument has explored several approaches. Public tours of the Carnegie Quarry have taken place since its discovery in 1909. In the early 1950s the monument erected a temporary building over a portion of the remaining Carnegie Quarry to protect and display in situ fossils, with the more extensive permanent construction of the Quarry Visitor Center completed in 1958, including a fossil preparation laboratory and museum collections space. Over time this structure was affected by the constant movement of the bedrock, requiring its overhaul in the early 2000s, resulting in today's Quarry Exhibit Hall. The park's museum collections were recently relocated to a facility at the Utah Field House of Natural History State Park Museum, where new facilities and a preparation laboratory are available to accommodate these extensive fossil collections. Other in situ fossil resources in the park have been made accessible along the Fossil Discovery Trail, or through tours to active quarries. Most of the fossil resources in the park are not suited for in situ display and require traditional excavation and curation practices. [ABSTRACT FROM AUTHOR]

Spinosaurids are a highly morphologically specialized clade of large tetanuran theropod dinosaurs, characterized by their proportionally long, narrow snouts and conical teeth with fluted surfaces. The unusual morphology of spinosaurids has been usually compared with modern crocodilians, but distinct differences between them have been reported as well. Here, numerous craniodental characters that are shared by spinosaurids and large, robust phytosaurs often termed as "brachyrostral" forms are reviewed. Phytosaurs are a clade of carnivorous archosauriforms that resemble crocodilians in overall morphology, and as such a similar lifestyle has been inferred for them as well. Although based on preliminary observations, the shared craniodental characters of spinosaurids and "brachyrostral" phytosaurs, including those not shared with crocodilians, raise the possibility that at least some aspects of the lifestyle of these extinct archosauriform clades were more similar to each other rather than to that of crocodilians [ABSTRACT FROM AUTHOR]

The morphology of the skull and endocranium of juvenile and adult specimens of the basal ceratopsian dinosaur P. sibiricus from the Lower Cretaceous Ilek formation (Kemerovo oblast-Kuzbass, Western Siberia, Russia) is described using micro-computed tomography scans and three-dimensional modelling. The diagnostic cranial characters of P. sibiricus include premaxilla-rostral canal present, maxillary fossa and maxillary protuberance absent, ten maxillary teeth in adults, maxillary-lacrimal contact, postorbital horn composed of the postorbital and the jugal present, large ventrolaterally projecting pyramidal jugal horns, deeply bifurcating jugal posterior process, external mandibular fenestra absent, dentary flange lacks the anterior corner but has a prominent posterior angle extending on the angular, and angular tuber projecting laterally at the posterior end of the ventral flange. [ABSTRACT FROM AUTHOR]

Although the living relatives of the Mesozoic flora were once assumed to constitute a nutritionally poor diet for dinosaur herbivores, in vitro fermentation of their foliage has shown that gymnosperms, ferns, and fern relatives can be as highly digestible as angiosperm grasses and dicots. Because nutritional information cannot be preserved in the fossil record, this laboratory approach, first published in 2008, provides a novel alternative to evaluate the digestive quality of the plants that were available to dinosaur megaherbivores such as sauropods. However, very few further studies have since been conducted to supplement and confirm the high fermentative capacity of nonangiospermous taxa. Here we show that the living relatives of the Araucariaceae and Equistaceae are consistently highly digestible, even between taxa and when influenced by environmental and biological factors, while fern taxa are inconsistent on the family level. These results reinforce previous findings about the high energetic potential of Jurassic-age plant families. Fourteen species of fern and gymnosperm foliage from five Jurassic families were collected in the spring and fall, then analyzed for their digestibility using the in vitro Hohenheim gas test. Equisetum, Araucaria, and Angiopteris were the most digestible genera in both seasons, while Agathis, Wollemia, and Marattia were the least digestible. The season in which specimens were collected was found to have to a significant effect on gas production in four out of 16 samples (P < 0.05). Furthermore, leaf maturity influences digestibility in Marattia attenuata (P < 0.05), yet not in Cyathea cooperi (P = 0.24). Finally, the species of the rumen fluid donor did not influence digestibility (P = 0.74). With the original data set supplemented by one new genus and four species, this study confirms and expands previous results about the nutritional capacity of the living relatives of the Jurassic flora. [ABSTRACT FROM AUTHOR]

Geomorphological surveys and terrain analysis are essential for geomorphology, hydrology, and geographic information systems (GIS). Terrain characterization parameters are fundamental for comprehending geomorphological processes, delineating landforms, and evaluating geohazards. Hence, this study relies on data from the Gaofen-2 satellite (GF-2) and the Advanced Land Observing Satellite Digital Elevation Model (ALOS DEM). Focusing on the ring tectonics landform of Dinosaur Valley, the research utilizes visual interpretation, GIS terrain parameter extraction techniques, and visual mapping to identify, measure, and analyze terrain features. The results indicate that ALOS DEM can offer accurate geomorphic feature information. The optimal threshold for extracting the surface water system network is 150, and the optimal analysis window for extracting terrain feature parameters is 16 × 16 (0.04 km2), determined through statistical methods. This study reveals distinct double-ring linear features and prominent ring-shaped terrain characteristics by extracting terrain feature parameters and utilizing mathematical and statistical analysis. The topography gradually ascends from the center to the ridgeline and then descends to the valley line, resembling a bowl shape. This study highlights the potential application of ALOS DEM for accurately identifying topographic features in the intricate mountains of the Yunnan Plateau. It establishes a practical research framework for high-precision topographic datasets and geomorphological characterization, facilitating further analysis of the evolution of topographic development and the assessment of tectonic activity. [ABSTRACT FROM AUTHOR]

The Lohan Cura Formation (Albian) at the Cerro de los Leones locality (Neuquén Province, Patagonia, Argentina) yielded several fossil materials, especially sauropod specimens. Among these, Agustinia ligabuei includes postcranial elements of a single individual, with widely debated taxonomy and phylogeny. Here, we provide an extended osteological description and illustrations of the axial and appendicular elements of Agustinia, as well as a revised diagnosis. Moreover, the phylogenetic analysis including a new combination of morphological features recognises Agustinia as a basal Rebbachisauridae, closely related with other South American rebbachisaurids. Our results suggest a more diversified sauropod fauna in the Neuquén Basin, where different members of both neosauropod lineages (i.e. Macronaria and Diplodocoidea) survived in the same region during the Albian age. The reassessment of Agustinia as a basal rebbachisaurid improves our knowledge about the early stages of evolutionary history of Rebbachisauridae, adding new information on the morphological and taxonomic diversification of the clade during the Early Cretaceous of southwestern Gondwana. [ABSTRACT FROM AUTHOR]

Ankylopollexia was an abundant and diverse clade of ornithopods present in North America, Europe, Africa, and Asia from the Late Jurassic to the Late Cretaceous. However, the relationships between the basal ankylopollexians are poorly understood. A new ankylopollexian ornithopod genus and species is described here, based on a dentary tooth, an ungual pollex of the manus, and an almost complete left hindlimb. The fossils come from deposits of the Villar del Arzobispo Formation (upper Kimmeridgian–Tithonian). Phylogenetic analysis revealed that Oblitosaurus bunnueli gen. et sp. nov. is the basalmost member of Ankylopollexia, together with Draconyx loureiroi. Furthermore, these results have relevant taxonomic implications for the genus Camptosaurus , being the first phylogenetic analysis to support the monophyly of Camptosaurus species. The estimated size of Oblitosaurus bunnueli suggests that it is the largest ornithopod described in the Upper Jurassic of Europe and one of the largest around the world, and could be the trackmaker of large ornithopod tracks found in the Upper Jurassic of the Iberian Peninsula. This discovery increases the known ankylopollexian diversity in Iberia, revealing the presence of an Iberian basal ankylopollexian clade that does not appear to be present in the contemporaneous outcrops of North America. [ABSTRACT FROM AUTHOR]

Natal down is a feather stage that differs in both form and function from the definitive feathers of adult birds. It has a simpler structure that has been speculated to be similar to the body coverings of non‐avian dinosaurs. However, inference of the evolution of natal down has been limited by our understanding of its structural variation in extant birds. Most descriptive work has focused on neognathous birds, limiting our knowledge of the full diversity of feathers in extant taxa. Here, we describe the natal down of a post‐hatch ostrich (Struthio camelus) and compare it to that of a post‐hatch quail (Coturnix coturnix). We confirm the presence of featherless spaces (apteria) in S. camelus and the lack of barbules on the tips of natal down in both species. We also find differences between dorsal and ventral natal down structures, such as barbule density in S. camelus and the extent of the bare portion of the barb in both species. Surprisingly, we do not find that the neoptiles of either species follow the ideal morphologies for increasing insulation. Finally, we hypothesize that the different barb types present in S. camelus natal down result from a large addition of new barb ridges during development, which is not known except in feathers with a rachis. These results have implications for our understanding of how structure informs function and development in understudied feather types, such as those shared by non‐avian dinosaurs. [ABSTRACT FROM AUTHOR]

The 100 m thick stratigraphic section exposed at Dinosaur Provincial Park (DPP; southern Alberta) contains bentonites that have been used for more than 30 years to date DPP's rocks and fossils using the K–Ar decay scheme. Limited reproducibility among different vintages of K–Ar and 40Ar/39Ar ages inhibited the development of a high-resolution chronostratigraphy. Here, we employ and further test a recently completed U–Pb geochronology and associated age-stratigraphy model to update temporal constraints on the Park's bentonites, formational contacts, and other markers. In turn, we document rock accumulation rates and calibrate ages and durations of informal megaherbivore dinosaur assemblage zones and other biozones. Weighted mean 206 Pb/238 U ages from five bentonites range from 76.718 ± 0.020 to 74.289 ± 0.014 Ma (2σ internal uncertainties) through an interval of 88.75 m, indicating a duration of ∼2.43 Myr and an overall rock accumulation rate of 3.65 ± 0.04 cm/ka. An increase in rate above the Oldman–Dinosaur Park formational contact conforms to a regionally expressed pattern of increased accommodation at ∼76.3 Ma across Alberta and Montana. Palynological biozone data suggest a condensed section/hiatus in the uppermost portion of the Oldman Formation. Dinosaur assemblage zones exhibit durations of ∼700–600 kyr and are significantly shorter than those in the overlying Horseshoe Canyon Formation. A decreased rate in dinosaur assemblage turnovers in the last eight million years of the Mesozoic in western Canada may be explained by withdrawal of the Western Interior Seaway and the expansion of ecologically homogenous lowlands in its wake. [ABSTRACT FROM AUTHOR]

In Russia, sauropod remains have been found in deposits of the Middle Jurassic of Western Siberia (Mamenchisauridae); the Lower Cretaceous of the Volga region (Volgatitan simbirskiensis), Transbaikalia (Tengrisaurus starkovi), and Western Siberia (Sibirotitan astrosacralis); and the Upper Cretaceous of the Far East (Opisthocoelicaudidae). Most finds from the Lower Cretaceous belong to titanosaurs (Lithostrotia). The Lower Cretaceous deposits of Western Siberia are the most promising in terms of the search for articulated remains of sauropods. [ABSTRACT FROM AUTHOR]

Background: Range of motion in the forelimb of the Upper Cretaceous theropod dinosaur Mononykus olecranus, a member of the family Alvarezsauridae, has previously been investigated. However, the method used to investigate range of motion at the shoulder in M. olecranus did not follow the standardized procedure used in subsequent studies. The latter procedure yields more reliable results, and its standardization provides that its results are directly comparable to the results of similar studies in other species. I therefore reinvestigated the range of motion at the shoulder in M. olecranus, using the latter procedure. Methods: Casts of the left scapula and coracoid of M. olecranus were posed on a horizontal surface, supported from beneath with modeling clay, with the medial surface of the scapula facing toward the horizontal surface. A cast of the left humerus was posed at the limits of motion through the transverse and parasagittal planes. Photos of the poses in orthal views were superimposed and used to measure range of motion, which was measured as the angle between lines drawn down the long axis of the humerus in each position. Results: Through the transverse plane, the humerus of M. olecranus could be elevated to a subhorizontal position and depressed to a subvertical position. It could move through the parasagittal plane from a subvertical position at full protraction to a position above the horizontal at full retraction. These results correct the previous mischaracterization of shoulder motion in M. olecranus as restricted to a small arc with the arms held in a permanent sprawl. The range of humeral motion in M. olecranus is much greater than that found by the previous method and allowed the animal to tuck its arms in at the sides, in addition to allowing them to sprawl so as to orient the palm downward. The wide range of humeral motion allowed M. olecranus to forage for insects by employing hook-and-pull digging at surfaces with a wider range of orientations than the previous study showed to be possible. [ABSTRACT FROM AUTHOR]

Marshall et al. recently estimated population densities, range sizes, instant and cumulative total population sizes for Tyrannosaurus rex with narrow ranges of uncertainly. I revisit the assumptions that led them to these conclusions and show that many of these parameters are associated with much wider margins of error than they estimated. Biogeographic estimates seem to have been especially unrealistic, seriously hampering the effort to calculate population level parameters. I posit that biogeographic and ecological uncertainties make it extremely unlikely to be able to estimate population sizes of long-extinct species.