A new species of Cricosaurus (Thalattosuchia, Metriorhynchidae) from the Upper Jurassic of southern Germany.

Here we describe a new species of the metriorhynchid thalattosuchian Cricosaurus, C. bambergensis sp. nov., from the Upper Jurassic Torleite Formation of Wattendorf near Bamberg, Bavaria (southern Germany). The holotype and only known specimen is a nearly complete skeleton that shows a number of diagnostic traits including a bicarinate dentition formed by labiolingually compressed tooth crowns that lack a conspicuous enamel ornamentation and the presence of a distinct midline ridge with paired depressions on the palatines. Our phylogenetic analysis recovers a grouping of Cricosaurus bambergensis sp. nov. with C. elegans and C. suevicus. The implications of the new Cricosaurus species to the species complex from the late Kimmeridgian–early Tithonian of southern Germany is discussed. Our description of C. bambergensis demonstrates that the specific, and morphological, diversity of Cricosaurus in southern Germany was higher than previously thought. This coincides with the recent trend of re-evaluating the species-complexes of extant taxa, and the identification of new “cryptic species”. As such, the crocodylomorph fossil record will need to be re- examined to ensure there is not an underestimation of their biodiversity

Lower Rotational Inertia and Larger Leg Muscles Indicate More Rapid Turns in Tyrannosaurids Than in Other Large Theropods

Synopsis: Tyrannosaurid dinosaurs had large preserved leg muscle attachments and low rotational inertia relative to their body mass, indicating that they could turn more quickly than other large theropods. Methods: To compare turning capability in theropods, we regressed agility estimates against body mass, incorporating superellipse-based modeled mass, centers of mass, and rotational inertia (mass moment of inertia). Muscle force relative to body mass is a direct correlate of agility in humans, and torque gives potential angular acceleration. Agility scores therefore include rotational inertia values divided by proxies for (1) muscle force (ilium area and estimates of m. caudofemoralis longus cross-section), and (2) musculoskeletal torque. Phylogenetic ANCOVA (phylANCOVA) allow assessment of differences in agility between tyrannosaurids and non-tyrannosaurid theropods (accounting for both ontogeny and phylogeny). We applied conditional error probabilities a(p) to stringently test the null hypothesis of equal agility. Results: Tyrannosaurids consistently have agility index magnitudes twice those of allosauroids and some other theropods of equivalent mass, turning the body with both legs planted or pivoting over a stance leg. PhylANCOVA demonstrates definitively greater agilities in tyrannosaurids, and phylogeny explains nearly all covariance. Mass property results are consistent with those of other studies based on skeletal mounts, and between different figure-based methods (our main mathematical slicing procedures, lofted 3D computer models, and simplified graphical double integration). Implications: The capacity for relatively rapid turns in tyrannosaurids is ecologically intriguing in light of their monopolization of large (\u3e400 kg), toothed dinosaurian predator niches in their habitats

Cancellous bone and theropod dinosaur locomotion. Part I—an examination of cancellous bone architecture in the hindlimb bones of theropods

This paper is the first of a three-part series that investigates the architecture of cancellous (‘spongy’) bone in the main hindlimb bones of theropod dinosaurs, and uses cancellous bone architectural patterns to infer locomotor biomechanics in extinct non-avian species. Cancellous bone is widely known to be highly sensitive to its mechanical environment, and has previously been used to infer locomotor biomechanics in extinct tetrapod vertebrates, especially primates. Despite great promise, cancellous bone architecture has remained little utilized for investigating locomotion in many other extinct vertebrate groups, such as dinosaurs. Documentation and quantification of architectural patterns across a whole bone, and across multiple bones, can provide much information on cancellous bone architectural patterns and variation across species. Additionally, this also lends itself to analysis of the musculoskeletal biomechanical factors involved in a direct, mechanistic fashion. On this premise, computed tomographic and image analysis techniques were used to describe and analyse the three-dimensional architecture of cancellous bone in the main hindlimb bones of theropod dinosaurs for the first time. A comprehensive survey across many extant and extinct species is produced, identifying several patterns of similarity and contrast between groups. For instance, more stemward non-avian theropods (e.g. ceratosaurs and tyrannosaurids) exhibit cancellous bone architectures more comparable to that present in humans, whereas species more closely related to birds (e.g. paravians) exhibit architectural patterns bearing greater similarity to those of extant birds. Many of the observed patterns may be linked to particular aspects of locomotor biomechanics, such as the degree of hip or knee flexion during stance and gait. A further important observation is the abundance of markedly oblique trabeculae in the diaphyses of the femur and tibia of birds, which in large species produces spiralling patterns along the endosteal surface. Not only do these observations provide new insight into theropod anatomy and behaviour, they also provide the foundation for mechanistic testing of locomotor hypotheses via musculoskeletal biomechanical modelling

Osteoderm distribution has low impact on the centre of mass of stegosaurs

It has been hypothesized that the pronounced differences of stegosaur humeral shapes, with large forms having more slender and small forms having more robust humeri, may be explained by a difference in relative centre of mass (COM) placement caused by differing distributions of osteoderms. To test this hypothesis, digital 3-D models of the bones and osteoderms of the Tanzanian stegosaur Kentrosaurus aethiopicus and of the North American stegosaur Stegosaurus armatus were used to create a 3-D computer-aided design life reconstruction. On these models osteoderm placement was varied drastically, recreating both existing and hypothetical forms. These models show that COM position varies somewhat with realistic osteoderm distributions, but insufficiently to explain major differences in humeral shape. The uniform weight distribution between forelimbs and hindlimbs found between the two taxa also casts doubt on the hypothesis that differences in relative COM position caused by other factors than osteoderm distribution can explain differences in humeral robustness

Full-body biomechanical model and novel forelimb muscle forces in Tyrannosaurus rex

Background: Tyrannosaurus rex is a popularly studied non-avian dinosaur with hundreds of papers investigating different aspects of its biology. The biomechanics of T. rex is of particular interest, with many analyses examining its locomotion and feeding. However, biomechanical models often focus on only one region of the body rather than incorporating multiple and some muscle groups have never been previously reconstructed in this taxon. Here we present (1) a new full-body model of Tyrannosaurus musculature, and (2) muscle force estimates for forelimb protractors and retractors, which have never yet been biomechanically analyzed. Methods: We created this model by generating a 3D render of a Tyrannosaurus rex’s skeleton with photogrammetry and sculpting the musculature onto the skeleton. The lengths and volumes of these scaled muscle models were then measured to calculate their physiological cross-sectional areas and ultimately estimate the maximum contractile force of each muscle for three possible fiber lengths. Results: The largest of the humeral protractors, the m. pectoralis, was estimated to have a maximum contractile force of 3,860 N – 11,000 N, while the largest humeral retractor, the m. latissimus dorsi, was estimated to have a maximum contractile force of 3,770 N – 10,800 N. Discussion: These forces will inform future calculations to explore how T. rex could use different muscle groups in its movements in addition to developing a better understanding of its forelimb biomechanics, which are largely undescribed. Furthermore, these muscle models will be presented as a digital atlas of T. rex’s skeletal muscle morphology

The Tail of the Late Jurassic Sauropod Giraffatitan brancai: Digital Reconstruction of Its Epaxial and Hypaxial Musculature, and Implications for Tail Biomechanics

Dinosaur locomotion and biomechanics, especially of their pelvic girdles and hindlimbs, have been analyzed in numerous studies. However, detailed volumetric musculoskeletal models of their tails are rarely developed. Here, we present the first detailed three-dimensional volumetric reconstruction of the caudal epaxial and hypaxial musculature of the Late Jurassic sauropod Giraffatitan brancai, and highlight the importance and necessity of 3D modeling in musculoskeletal reconstructions. The tail of this basal macronarian is relatively short compared to diplodocids and other coexisting macronarians. The center of mass lies well in front of the hindlimbs, which support only ca. half the body weight. Still, our reconstruction suggests a total weight for the entire tail of ca. 2500 kg. We conclude that the hypaxial and tail-related hindlimb muscles (most specifically the M. caudofemoralis longus and its counterpart the M. ilioischiocaudalis) in Giraffatitan were well developed and robustly built, compensating for the shorter length of the M. caufodemoralis longus, the main hindlimb retractor muscle, in comparison with other sauropods. Our methodology allows a better-constrained reconstruction of muscle volumes and masses in extinct taxa, and thus force and weight distributions throughout the tail, than non-volumetric approaches.Peer Reviewe

A path to gigantism: Three‐dimensional study of the sauropodomorph limb long bone shape variation in the context of the emergence of the sauropod bauplan

International audienc

Comparing surface digitization techniques in palaeontology using visual perceptual metrics and distance computations between 3D meshes

The use of surface digitization techniques and methods in palaeontology has increased in the last two decades, mainly due to recent improvements in devices and software. However, many digitization efforts are published only as 3D models, with only a few details on the exact protocols used and sometimes not even indicating how to access these digital data, thus reducing the long‐term reusability of the obtained files. It is important to include this information, as the applied techniques and workflows have significant effects on the final quality of 3D models. We compare 3D meshes created by seven different surface digitization techniques and protocols for a sauropod caudal vertebra and a testudine turtle in a flat slab of rock. These two specimens represent typical examples of objects in vertebrate palaeontology collections, making them a suitable sample for our tests. Besides these quantitative and topological comparisons we also have computed visual perceptual metrics, which aim to predict the visual quality of a 3D model as perceived by a human observer. Our results agree with previous works, confirming that photogrammetry is one of the most suitable options for obtaining high quality 3D models of fossils, producing higher quality meshes than current structured light 3D scanners.Berliner Hochschulprogramm für Wissenschaftlerinnen und Künstlerinnen ‚DiGiTal – Digitalisierung: Gestaltung und Transformation‘Xunta de Galicia, Spai