Aardonyx celestae gen. et sp. nov. is described from the upper Elliot Formation (Early Jurassic) of South Africa. It can be diagnosed by autapomorphies skull, particularly jaws, cervical column, forearm and pes. found to sister group a clade obligatory quadrupedal sauropodomorphs ( Melanorosaurus + Sauropoda) thus lies at heart basal sauropodomorph–sauropod transition. The narrow jaws A. retain pointed symphysis but appear have lacked fleshy cheeks. Broad, U-shaped were previously thought...

ABSTRACT Sauropods have a unique digitigrade and semi-tubular manus whose shape has been used as synapomorphy that unites most sauropod taxa. The vertical orientation arrangement of the metacarpale suggest improved mechanical ability forelimb to support great weight. However, evolutionary mechanism responsible for modifying relatively flat metacarpus basal saurischians into remained uninvestigated. Furthermore, trackway evidence shows pronation was more developed in sauropods than other...

Abstract In nonavian dinosaur long bones, the once‐living chondroepiphysis (joint surface) overlay a now‐fossilized calcified cartilage zone. Although shape of this zone is used to infer locomotion, it remains unclear how much reflects shape. We tested hypothesis that overlying in extant archosaurs. Long bones with intact epiphyses from American alligators ( Alligator mississippiensis ), helmeted guinea fowl Numida meleagris and juvenile ostriches Struthio camelus ) were measured digitized...

Postcranial skeletal pneumaticity (PSP) is present in a range of basal sauropodomorphs spanning the sauropodomorph-sauropod transition.We describe PSP five taxa, Plateosaurus engelhardti, Eucnemesaurus fortis, Aardonyx celestae, Antetonitrus ingenipes, and an unnamed sauropod from Spion Kop, South Africa (hereafter referred to as Kop sauropod).The apparently sporadic its occurrence has only been observed very few specimens, which it limited extent, affecting posterior cervical vertebrae...

Abstract The early evolution of sauropod dinosaurs remains poorly understood, with a paucity unequivocal taxa known from the first twenty million years Jurassic. Recently, Early Jurassic South Africa has yielded an assemblage dental and post-cranial displaying more apomorphic character suite than any other similarly aged sauropodomorph. These are interpreted as new species basal recovered cladistically sister taxon to Vulcanodon +more derived Sauropoda, underscoring its importance for our...

The earliest eutherian mammals were small-bodied locomotor generalists with a forelimb morphology that strongly resembles of extant rats. Understanding the kinematics humerus, radius, and ulna rats can inform constrain hypotheses concerning typical posture mobility in early forelimbs. locomotion Rattus norvegicus has been extensively studied, but three-dimensional bones themselves remains under-explored. Here, for first time, we use markerless XROMM (Scientific Rotoscoping) to explore long...

Abstract Morphometric analyses of sauropod limbs have the potential to illuminate functional aspects locomotion and paleobiology. However, limb dimensions typically show few discernible morphological trends because large size differences among individuals in a sample. For sauropods, combined both dimension shape may be more desirable. Numerous humeri femora from Apatosaurus, Diplodocus, Camarasaurus provide an opportunity explore compare morphology contemporaneous, sympatric sauropods....

Abstract Neosauropod dinosaurs were gigantic, herbivorous dinosaurs. Given that the limb skeleton is essentially a plastic, mobile framework supports and moves body, analysis of long bone scaling can reveal adaptations supported neosauropod gigantism. Previously, analyses linear dimensions have revealed relatively isometric pattern for humerus femur neosauropods. Here, combined dimensions, cortical area, shape across six taxa used to test hypothesis bones scaled isometrically investigate...

Eutherian mammals and saurischian dinosaurs both evolved lineages of huge terrestrial herbivores. Although significantly more were giants than eutherians, the long bones taxa scale similarly suggest that locomotion was dynamically similar. However, articular cartilage is thin in eutherian but thick dinosaurs, differences could have contributed to, or limited, how frequently gigantism evolved. Therefore, we tested hypothesis sub-articular bone, which supports cartilage, changes shape...

ABSTRACT Sexual size dimorphism (SSD) is prevalent among extant vertebrates and presumably was as common fossil archosaurs. Here, we test the hypothesis that femur shape a reliable indicator of sex archosaurs using linear geometric morphometric analyses on large sample sexed Alligator mississippiensis femora. Linear regression femoral dimensions onto length in alligators shows male femora are largest stoutest midshaft articular dimensions, whereas females show more variation their...

ABSTRACT A new basal sauropodomorph dinosaur, Arcusaurus pereirabdalorum, sp. nov., is named and described on the basis of a partial, disarticulated but associated skull dispersed cranial postcranial elements from at least two individuals. part distinctive local fauna upper Elliot Formation (Lower Jurassic) in Senekal District, Free State, South Africa. It can be diagnosed by various details premaxilla, nasal, dentary shape distal caudal vertebrae. The taxon displays an unusual mix...

ABSTRACT Wide‐gauge posture of titanosauriform sauropods remains an enigmatic peculiarity among terrestrial vertebrates. Here, two‐dimensional geometric morphometrics and thin plate splines analyses were used to quantitatively analyze shape differences sauropodomorph humeri femora identify how these elements may differ according body gauge. Results demonstrate that titanosauriforms generally possess proportionately gracile in comparison other sauropods, with relatively more medially oriented...

Abstract The shark heterocercal caudal fin and its contribution to locomotion are of interest biologists paleontologists. Current hydrodynamic data show that the stiff dorsal lobe leads ventral lobe, both lobes tail synchronized during propulsion, shape reflects overall locomotor function. Given difficulties surrounding analysis fins in vivo , little is known about changes related ontogeny sex sharks. A quantifiable may provide an acceptable proxy for inferring gross functional morphology...

Quadrupedality evolved four independent times in dinosaurs; however, the constraints associated with these transitions limb anatomy and function remain poorly understood, particular evolution of forearm posture rotational ability (i.e., active pronation supination). Results previous qualitative studies are inconsistent, likely due to an inability quantitatively assess likelihood their conclusions. We attempt quantify antebrachial mobility using radius bone because its morphology is distinct...

Abstract Bipedalism evolved multiple times within archosaurs, and relatively shorter forelimbs characterize both crocodyliforms nonavian dinosaurs. Analysis of a comprehensive ontogenetic sequence specimens (embryo to adult) the sauropodomorph Massospondylus has shown that bipedal limb proportions result from negative forelimb allometry. We ask, is allometry pattern basal amplified in certain taxa produce bipedalism? Given phylogenetic position extant crocodylians their forelimb, we tested...

The extinct megatooth shark, Otodus megalodon (Lamniformes: Otodontidae), is known primarily from its gigantic teeth in the late Neogene marine fossil record. It to reach at least 14.1‒15.3 m length, but reproductive biology and ontogenetic growth pattern have remained largely realm of speculation. Here, we examined incremental bands vertebrae a 9.2-m-long individual O. megalodon, revealing that shark was born large, 2 died age 46. This large size birth characteristic lamniform sharks...

Rarity of soft tissue preservation, including articular cartilage, in the fossil record hinders creation biologically-realistic mechanical models. Previous studies cartilage extant taxa have documented important aspects shapes and thicknesses, but these insights remain generalized yet to see systematic implementation biomechanical modeling. Herein, we present a new method for modeling joints that allows testing hypotheses about morphology extinct taxa. Our case study examines left elbow...

ABSTRACT Absence of an ossified calcaneum has been suggested as a synapomorphy Diplodocidae and used to construct sauropod phylogenetic hypotheses. Restudy material at the Carnegie Museum Natural History revealed diplodocid pes with unknown pedal element. The relatively complete pes, CM 30767, identified Diplodocus. Comparisons known calcanea, carpals, phalanges, indicate that this element is calcaneum. presence in important functional systematic implications. Ossified calcanea may have...

Abstract The functional morphology and kinematics of the elbow joint remain relatively understudied in squamates. Previous investigations lizard suggest long‐axis rotation (LAR) radius ulna during stance allows manus to pronated forelimb retraction. Using XROMM (X‐ray Reconstruction Moving Morphology), we explored range 3D movements humerus, radius, three adult male Central bearded dragons ( Pogona vitticeps ) trackway walking. Our data indicate that P. experiences significant rotations all...