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1.
J R Soc Interface ; 19(196): 20220588, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36349446

RESUMO

Fossil tracks are important palaeobiological data sources. The quantitative analysis of their shape, however, has been hampered by their high variability and lack of discrete margins and landmarks. We here present the first approach using deep convolutional neural networks (DCNNs) to study fossil tracks, overcoming the limitations of previous statistical approaches. We employ a DCNN to discriminate between theropod and ornithischian dinosaur tracks based on a total of 1372 outline silhouettes. The DCNN consistently outperformed human experts on an independent test set. We also used the DCNN to classify tracks of a large tridactyl trackmaker from Lark Quarry, Australia, the identity of which has been subject to intense debate. The presented approach can only be considered a first step towards the wider application of machine learning in fossil track research, which is not limited to classification problems. Current limitations, such as the subjectivity and information loss inherent in interpretive outlines, may be overcome in the future by training neural networks on three-dimensional models directly, though this will require an increased uptake in digitization among workers in the field.


Assuntos
Dinossauros , Animais , Humanos , Dinossauros/anatomia & histologia , Aprendizado de Máquina , Redes Neurais de Computação , Fósseis , Austrália
2.
Sci Rep ; 12(1): 19965, 2022 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-36402874

RESUMO

Dromaeosaurids were bird-like dinosaurs with a predatory ecology known to forage on fish, mammals and other dinosaurs. We describe Daurlong wangi gen. et sp. nov., a dromaeosaurid from the Lower Cretaceous Jehol Biota of Inner Mongolia, China. Exceptional preservation in this specimen includes a large bluish layer in the abdomen which represents one of the few occurrences of intestinal remnants among non-avian dinosaurs. Phylogenetically, Daurlong nests among a lineage of short-armed Jehol Biota species closer to eudromaeosaurs than microraptorines. The topographic correspondence between the exceptionally preserved intestine in the more stem-ward Scipionyx and the remnants in the more birdlike Daurlong provides a phylogenetic framework for inferring intestine tract extent in other theropods lacking fossilized visceral tissues. Gastrointestinal organization results conservative among faunivorous dinosaurs, with the evolution of a bird-like alimentary canal restricted to avialan theropods.


Assuntos
Dinossauros , Animais , Dinossauros/anatomia & histologia , Filogenia , Fósseis , Evolução Biológica , Aves , Intestinos , Mamíferos
3.
Proc Natl Acad Sci U S A ; 119(47): e2205476119, 2022 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-36375073

RESUMO

Anatomy of the first flying feathered dinosaurs, modern birds and crocodylians, proposes an ancestral flight system divided between shoulder and chest muscles, before the upstroke muscles migrated beneath the body. This ancestral flight system featured the dorsally positioned deltoids and supracoracoideus controlling the upstroke and the chest-bound pectoralis controlling the downstroke. Preserved soft anatomy is needed to contextualize the origin of the modern flight system, but this has remained elusive. Here we reveal the soft anatomy of the earliest theropod flyers preserved as residual skin chemistry covering the body and delimiting its margins. These data provide preserved soft anatomy that independently validate the ancestral theropod flight system. The heavily constructed shoulder and more weakly constructed chest in the early pygostylian Confuciusornis indicated by a preserved body profile, proposes the first upstroke-enhanced flight stroke. Slender ventral body profiles in the early-diverging birds Archaeopteryx and Anchiornis suggest habitual use of the pectoralis could not maintain the sternum through bone functional adaptations. Increased wing-assisted terrestrial locomotion potentially accelerated sternum loss through higher breathing requirements. Lower expected downstroke requirements in the early thermal soarer Sapeornis could have driven sternum loss through bone functional adaption, possibly encouraged by the higher breathing demands of a Confuciusornis-like upstroke. Both factors are supported by a slender ventral body profile. These data validate the ancestral shoulder/chest flight system and provide insights into novel upstroke-enhanced flight strokes and early sternum loss, filling important gaps in our understanding of the appearance of modern flight.


Assuntos
Dinossauros , Ombro , Animais , Ombro/anatomia & histologia , Dinossauros/anatomia & histologia , Asas de Animais/fisiologia , Aves/fisiologia , Esterno/anatomia & histologia , Voo Animal/fisiologia , Fósseis , Evolução Biológica
4.
Proc Biol Sci ; 289(1984): 20220740, 2022 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-36196539

RESUMO

Significant evolutionary shifts in locomotor behaviour often involve comparatively subtle anatomical transitions. For dinosaurian and avian evolution, medial overhang of the proximal femur has been central to discussions. However, there is an apparent conflict with regard to the evolutionary origin of the dinosaurian femoral head, with neontological and palaeontological data suggesting seemingly incongruent hypotheses. To reconcile this, we reconstructed the evolutionary history of morphogenesis of the proximal end of the femur from early archosaurs to crown birds. Embryological comparison of living archosaurs (crocodylians and birds) suggests the acquisition of the greater overhang of the femoral head in dinosaurs results from additional growth of the proximal end in the medial-ward direction. On the other hand, the fossil record suggests that this overhang was acquired by torsion of the proximal end, which projected in a more rostral direction ancestrally. We reconcile this apparent conflict by inferring that the medial overhang of the dinosaur femoral head was initially acquired by torsion, which was then superseded by mediad growth. Details of anatomical shifts in fossil forms support this hypothesis, and their biomechanical implications are congruent with the general consensus regarding broader morpho-functional evolution on the avian stem.


Assuntos
Dinossauros , Cabeça do Fêmur , Animais , Evolução Biológica , Aves , Dinossauros/anatomia & histologia , Fósseis , Morfogênese , Filogenia
7.
Sci Rep ; 12(1): 17321, 2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-36243889

RESUMO

Intraspecific variation in growth trajectories provides a fundamental source of variation upon which natural selection acts. Recent work hints that early dinosaurs possessed elevated levels of such variation compared to other archosaurs, but comprehensive data uniting body size, bone histology, and morphological variation from a stratigraphically constrained early dinosaur population are needed to test this hypothesis. The Triassic theropod Coelophysis bauri, known from a bonebed preserving a single population of coeval individuals, provides an exceptional system to assess whether highly variable growth patterns were present near the origin of Dinosauria. Twenty-four histologically sampled individuals were less than a year to at least four years old and confirm the right-skewed age distribution of the Coelophysis assemblage. Poor correlations among size, age, and morphological maturity strongly support the presence of unique, highly variable growth trajectories in early dinosaurs relative to coeval archosaurs and their living kin.


Assuntos
Dinossauros , Animais , Evolução Biológica , Tamanho Corporal , Dinossauros/anatomia & histologia , Fósseis , Filogenia
8.
PLoS One ; 17(10): e0266648, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36260601

RESUMO

Reconstructing the evolution, diversity, and paleobiogeography of North America's Late Cretaceous dinosaur assemblages require spatiotemporally contiguous data; however, there remains a spatial and temporal disparity in dinosaur data on the continent. The rarity of vertebrate-bearing sedimentary deposits representing Turonian-Santonian ecosystems, and the relatively sparse record of dinosaurs from the eastern portion of the continent, present persistent challenges for studies of North American dinosaur evolution. Here we describe an assemblage of ornithomimosaurian materials from the Santonian Eutaw Formation of Mississippi. Morphological data coupled with osteohistological growth markers suggest the presence of two taxa of different body sizes, including one of the largest ornithomimosaurians known worldwide. The regression predicts a femoral circumference and a body mass of the Eutaw individuals similar to or greater than that of large-bodied ornithomimosaurs, Beishanlong grandis, and Gallimimus bullatus. The paleoosteohistology of MMNS VP-6332 demonstrates that the individual was at least ten years of age (similar to B. grandis [~375 kg, 13-14 years old at death]). Additional pedal elements share some intriguing features with ornithomimosaurs, yet suggest a larger-body size closer to Deinocheirus mirificus. The presence of a large-bodied ornithomimosaur in this region during this time is consistent with the relatively recent discoveries of early-diverging, large-bodied ornithomimosaurs from mid-Cretaceous strata of Laurasia (Arkansaurus fridayi and B. grandis). The smaller Eutaw taxon is represented by a tibia preserving seven growth cycles, with osteohistological indicators of decreasing growth, yet belongs to an individual approaching somatic maturity, suggesting the co-existence of medium- and large-bodied ornithomimosaur taxa during the Late Cretaceous Santonian of North America. The Eutaw ornithomimosaur materials provide key information on the diversity and distribution of North American ornithomimosaurs and Appalachian dinosaurs and fit with broader evidence of multiple cohabiting species of ornithomimosaurian dinosaurs in Late Cretaceous ecosystems of Laurasia.


Assuntos
Dinossauros , Gafanhotos , Animais , Fósseis , Ecossistema , Dinossauros/anatomia & histologia , América do Norte , Região dos Apalaches
9.
Nature ; 610(7931): 313-318, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36198797

RESUMO

Pterosaurs, the first vertebrates to evolve powered flight, were key components of Mesozoic terrestrial ecosystems from their sudden appearance in the Late Triassic until their demise at the end of the Cretaceous1-6. However, the origin and early evolution of pterosaurs are poorly understood owing to a substantial stratigraphic and morphological gap between these reptiles and their closest relatives6, Lagerpetidae7. Scleromochlus taylori, a tiny reptile from the early Late Triassic of Scotland discovered over a century ago, was hypothesized to be a key taxon closely related to pterosaurs8, but its poor preservation has limited previous studies and resulted in controversy over its phylogenetic position, with some even doubting its identification as an archosaur9. Here we use microcomputed tomographic scans to provide the first accurate whole-skeletal reconstruction and a revised diagnosis of Scleromochlus, revealing new anatomical details that conclusively identify it as a close pterosaur relative1 within Pterosauromorpha (the lagerpetid + pterosaur clade). Scleromochlus is anatomically more similar to lagerpetids than to pterosaurs and retains numerous features that were probably present in very early diverging members of Avemetatarsalia (bird-line archosaurs). These results support the hypothesis that the first flying reptiles evolved from tiny, probably facultatively bipedal, cursorial ancestors1.


Assuntos
Dinossauros , Fósseis , Filogenia , Animais , Dinossauros/classificação , Ecossistema , Modelos Biológicos
10.
Curr Biol ; 32(20): R1166-R1172, 2022 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-36283386

RESUMO

If you find a bird bone in deposits from the Cretaceous period (145-66 million years ago), chances are it will belong to an enantiornithine bird. This extinct group of birds was mostly arboreal and dominated terrestrial environments from 130 to 66 million years ago. With approximately 90 known genera, they account for more than half of the known diversity of Mesozoic birds. Yet, despite apparently out-competing birds more closely related to living species in most Cretaceous continental environments, enantiornithines mysteriously went extinct at the end of the Cretaceous, alongside all other non-neornithine (crown-bird) dinosaurs.


Assuntos
Dinossauros , Fósseis , Animais , Aves , Osso e Ossos , Árvores , Evolução Biológica , Filogenia
11.
Curr Biol ; 32(18): R964-R967, 2022 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-36167048

RESUMO

Developmental biology and paleontology have a long history of reciprocal illumination. New research reveals that the embryonic development of the bird pelvis parallels the evolutionary transition from archosaurs to birds.


Assuntos
Dinossauros , Animais , Evolução Biológica , Biologia do Desenvolvimento , Dinossauros/anatomia & histologia , Fósseis , Paleontologia , Codorniz
12.
Proc Biol Sci ; 289(1983): 20221398, 2022 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-36168759

RESUMO

Among terrestrial vertebrates, only crown birds (Neornithes) rival mammals in terms of relative brain size and behavioural complexity. Relatedly, the anatomy of the avian central nervous system and associated sensory structures, such as the vestibular system of the inner ear, are highly modified with respect to those of other extant reptile lineages. However, a dearth of three-dimensional Mesozoic fossils has limited our knowledge of the origins of the distinctive endocranial structures of crown birds. Traits such as an expanded, flexed brain, a ventral connection between the brain and spinal column, and a modified vestibular system have been regarded as exclusive to Neornithes. Here, we demonstrate all of these 'advanced' traits in an undistorted braincase from an Upper Cretaceous enantiornithine bonebed in southeastern Brazil. Our discovery suggests that these crown bird-like endocranial traits may have originated prior to the split between Enantiornithes and the more crownward portion of avian phylogeny over 140 Ma, while coexisting with a remarkably plesiomorphic cranial base and posterior palate region. Altogether, our results support the interpretation that the distinctive endocranial morphologies of crown birds and their Mesozoic relatives are affected by complex trade-offs between spatial constraints during development.


Assuntos
Dinossauros , Orelha Interna , Animais , Evolução Biológica , Aves/anatomia & histologia , Encéfalo , Dinossauros/anatomia & histologia , Orelha Interna/anatomia & histologia , Fósseis , Mamíferos , Filogenia , Base do Crânio/anatomia & histologia
13.
Science ; 377(6610): 1031, 2022 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-36048930

RESUMO

Nearly complete specimen shows earliest dinosaurs needed a temperate climate.


Assuntos
Evolução Biológica , Clima , Dinossauros , Fósseis , Animais , Dinossauros/anatomia & histologia , Filogenia , Zimbábue
14.
PLoS One ; 17(9): e0268144, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36048811

RESUMO

In this study, we use an exceptional skeleton of the pachycephalosaur Stegoceras validum (UALVP 2) to inform a comprehensive appendicular muscle reconstruction of the animal, with the goal of better understanding the functional morphology of the pachycephalosaur postcranial skeleton. We find that S. validum possessed a conservative forelimb musculature, particularly in comparison to early saurischian bipeds. By contrast, the pelvic and hind limb musculature are more derived, reflecting peculiarities of the underlying skeletal anatomy. The iliotibialis, ischiocaudalis, and caudofemoralis muscles have enlarged attachment sites and the caudofemoralis has greater leverage owing to the distal displacement of the fourth trochanter along the femur. These larger muscles, in combination with the wide pelvis and stout hind limbs, produced a stronger, more stable pelvic structure that would have proved advantageous during hypothesized intraspecific head-butting contests. The pelvis may have been further stabilized by enlarged sacroiliac ligaments, which stemmed from the unique medial iliac flange of the pachycephalosaurs. Although the pubis of UALVP 2 is not preserved, the pubes of other pachycephalosaurs are highly reduced. The puboischiofemoralis musculature was likely also reduced accordingly, and compensated for by the aforementioned improved pelvic musculature.


Assuntos
Dinossauros , Animais , Dinossauros/anatomia & histologia , Membro Posterior/anatomia & histologia , Extremidade Inferior , Músculo Esquelético/anatomia & histologia , Pelve/anatomia & histologia
15.
Sci Rep ; 12(1): 16026, 2022 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-36163377

RESUMO

The spectacular fossil fauna and flora preserved in the Upper Cretaceous terrestrial strata of North America's Western Interior Basin record an exceptional peak in the diversification of fossil vertebrates in the Campanian, which has been termed the 'zenith of dinosaur diversity'. The wide latitudinal distribution of rocks and fossils that represent this episode, spanning from northern Mexico to the northern slopes of Alaska, provides a unique opportunity to gain insights into dinosaur paleoecology and to address outstanding questions regarding faunal provinciality in connection to paleogeography and climate. Whereas reliable basin-wide correlations are fundamental to investigations of this sort, three decades of radioisotope geochronology of various vintages and limited compatibility has complicated correlation of distant fossil-bearing successions and given rise to contradictory paleobiogeographic and evolutionary hypotheses. Here we present new U-Pb geochronology by the CA-ID-TIMS method for 16 stratigraphically well constrained bentonite beds, ranging in age from 82.419 ± 0.074 Ma to 73.496 ± 0.039 Ma (2σ internal uncertainties), and the resulting Bayesian age models for six key fossil-bearing formations over a 1600 km latitudinal distance from northwest New Mexico, USA to southern Alberta, Canada. Our high-resolution chronostratigraphic framework for the upper Campanian of the Western Interior Basin reveals that despite their contrasting depositional settings and basin evolution histories, significant age overlap exists between the main fossil-bearing intervals of the Kaiparowits Formation (southern Utah), Judith River Formation (central Montana), Two Medicine Formation (western Montana) and Dinosaur Park Formation (southern Alberta). Pending more extensive paleontologic collecting that would allow more rigorous faunal analyses, our results support a first-order connection between paleoecologic and fossil diversities and help overcome the chronostratigraphic ambiguities that have impeded the testing of proposed models of latitudinal provinciality of dinosaur taxa during the Campanian.


Assuntos
Dinossauros , Alberta , Animais , Teorema de Bayes , Bentonita , Dinossauros/anatomia & histologia , Fósseis , Chumbo , Filogenia
16.
J Anat ; 241(6): 1424-1440, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36065514

RESUMO

Two sets of teeth (diphyodonty) characterise extant mammals but not reptiles, as they generate many replacement sets (polyphyodonty). The transition in long-extinct species from many sets to only two has to date only been reported in Jurassic eucynodonts. Specimens of the Late Triassic brasilodontid eucynodont Brasilodon have provided anatomical and histological data from three lower jaws of different growth stages. These reveal ordered and timed replacement of deciduous by adult teeth. Therefore, this diphyodont dentition, as contemporary of the oldest known dinosaurs, shows that Brasilodon falls within a range of wide variations of typically mammalian, diphyodont dental patterns. Importantly, these three lower jaws represent distinct ontogenetic stages that reveal classic features for timed control of replacement, by the generation of only one replacement set of teeth. This data shows that the primary premolars reveal a temporal replacement pattern, importantly from directly below each tooth, by controlled regulation of tooth resorption and regeneration. The complexity of the adult prismatic enamel structure with a conspicuous intra-structural Schmelzmuster array suggests that, as in the case of extant mammals, this extinct species would have probably sustained higher metabolic rates than reptiles. Furthermore, in modern mammals, diphyodonty and prismatic enamel are inextricably linked, anatomically and physiologically, to a set of other traits including placentation, endothermy, fur, lactation and even parental care. Our analysis of the osteodental anatomy of Brasilodon pushes back the origin of diphyodonty and consequently, its related biological traits to the Norian (225.42 ± 0.37 myr), and around 25 myr after the End-Permian mass extinction event.


Assuntos
Dinossauros , Dente , Gravidez , Animais , Feminino , Odontogênese/fisiologia , Mamíferos/anatomia & histologia , Répteis/anatomia & histologia , Dinossauros/anatomia & histologia , Morfogênese , Dente/anatomia & histologia , Fósseis , Evolução Biológica
17.
Proc Natl Acad Sci U S A ; 119(39): e2211234119, 2022 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-36122246

RESUMO

Whether or not nonavian dinosaur biodiversity declined prior to the end-Cretaceous mass extinction remains controversial as the result of sampling biases in the fossil record, differences in the analytical approaches used, and the rarity of high-precision geochronological dating of dinosaur fossils. Using magnetostratigraphy, cyclostratigraphy, and biostratigraphy, we establish a high-resolution geochronological framework for the fossil-rich Late Cretaceous sedimentary sequence in the Shanyang Basin of central China. We have found only three dinosaurian eggshell taxa (Macroolithus yaotunensis, Elongatoolithus elongatus, and Stromatoolithus pinglingensis) representing two clades (Oviraptoridae and Hadrosauridae) in sediments deposited between ∼68.2 and ∼66.4 million y ago, indicating sustained low dinosaur biodiversity, and that assessment is consistent with the known skeletal remains in the Shanyang and surrounding basins of central China. Along with the dinosaur eggshell records from eastern and southern China, we find a decline in dinosaur biodiversity from the Campanian to the Maastrichtian. Our results support a long-term decline in global dinosaur biodiversity prior to 66 million y ago, which likely set the stage for the end-Cretaceous nonavian dinosaur mass extinction.


Assuntos
Biodiversidade , Dinossauros , Extinção Biológica , Fósseis , Animais , China , Dinossauros/classificação
18.
Curr Biol ; 32(20): 4501-4507.e2, 2022 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-36084648

RESUMO

Sauropod dinosaurs include the largest land animals to have walked the earth, mostly weighing 10-70 tons (e.g., Sander et al.1 and Carballido et al.2). Osteohistology suggests that derived physiological traits evolved near the origin of sauropod gigantism, including both rapid and uninterrupted growth from juvenile to adult with little developmental plasticity.1,3,4 This differs from the slower, seasonally interrupted growth of their direct ancestors, as evident in most non-sauropodan sauropodomorphs, which also show developmental plasticity in some groups. Accelerated but seasonally interrupted growth is present in Lessemsauridae, the sister clade to Sauropoda, which also attained giant adult body sizes (>10 tons).5 These observations suggest a correlation between giant size and accelerated growth. However, testing this evolutionary connection has been limited by the incomplete understanding of the growth patterns in some of the closest non-giant relatives of sauropods. We present the osteohistology of two such taxa, Aardonyx celestae and Sefapanosaurus zatronensis. Both exhibit highly vascularized woven-parallel complexes, with fibrolamellar complexes during early to mid-ontogeny, containing regular growth marks. These observations provide strong evidence for rapid but seasonally interrupted growth with limited developmental plasticity (indicated by the regular spacing of growth marks). Combined with our review of early branching sauropodomorph osteohistology, these results show that highly accelerated growth rates originated among smaller, non-sauropodan sauropodomorphs weighing 1 to 2 tons but preceded the origins of giant size (>10 tons). Therefore, the capacity for rapid bone tissue formation, a derived aspect of rapid growth seen in sauropods, did not evolve specifically to enable giant body sizes but may have been a prerequisite for them.


Assuntos
Dinossauros , Gigantismo , Animais , Fósseis , Evolução Biológica , Filogenia , Dinossauros/anatomia & histologia
19.
Sci Rep ; 12(1): 11621, 2022 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-35953515

RESUMO

The early evolution of thyreophoran dinosaurs is thought to have occurred primarily in northern continents since most evidence comes from the Lower and Middle Jurassic of Europe and North America. The diversification into stegosaurs and ankylosaurs is obscured by a patchy fossil record comprising only a handful of fragmentary fossils, most with uncertain phylogenetic affinities. Here we report the discovery of a new armoured dinosaur from the early Late Cretaceous of Argentina, recovered phylogenetically using various datasets either as a basal thyreophoran or a stem ankylosaur, closely related to Scelidosaurus. It bears unusual anatomical features showing that several traits traditionally associated with the heavy Cretaceous thyreophorans did not occur universally. Jakapil kaniukura gen. et sp. nov. is the first definitive thyreophoran species from the Argentinian Patagonia. Unlike most thyreophorans, it seems to show a bipedal stance, as in Scutellosaurus. Jakapil also shows that early thyreophorans had a much broader geographic distribution than previously thought. It is a member of an ancient basal thyreophoran lineage that survived until the Late Cretaceous in South America.


Assuntos
Dinossauros , Animais , Argentina , Dinossauros/anatomia & histologia , Fósseis , Filogenia , América do Sul
20.
Nature ; 609(7926): 313-319, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36045297

RESUMO

The vertebrate lineages that would shape Mesozoic and Cenozoic terrestrial ecosystems originated across Triassic Pangaea1-11. By the Late Triassic (Carnian stage, ~235 million years ago), cosmopolitan 'disaster faunas' (refs. 12-14) had given way to highly endemic assemblages12,13 on the supercontinent. Testing the tempo and mode of the establishment of this endemism is challenging-there were few geographic barriers to dispersal across Pangaea during the Late Triassic. Instead, palaeolatitudinal climate belts, and not continental boundaries, are proposed to have controlled distribution15-18. During this time of high endemism, dinosaurs began to disperse and thus offer an opportunity to test the timing and drivers of this biogeographic pattern. Increased sampling can test this prediction: if dinosaurs initially dispersed under palaeolatitudinal-driven endemism, then an assemblage similar to those of South America4,19-21 and India19,22-including the earliest dinosaurs-should be present in Carnian deposits in south-central Africa. Here we report a new Carnian assemblage from Zimbabwe that includes Africa's oldest definitive dinosaurs, including a nearly complete skeleton of the sauropodomorph Mbiresaurus raathi gen. et sp. nov. This assemblage resembles other dinosaur-bearing Carnian assemblages, suggesting that a similar vertebrate fauna ranged high-latitude austral Pangaea. The distribution of the first dinosaurs is correlated with palaeolatitude-linked climatic barriers, and dinosaurian dispersal to the rest of the supercontinent was delayed until these barriers relaxed, suggesting that climatic controls influenced the initial composition of the terrestrial faunas that persist to this day.


Assuntos
Dinossauros , Ecossistema , Animais , Clima , Fósseis , História Antiga , Filogenia , Filogeografia , Densidade Demográfica , Dinâmica Populacional , Esqueleto , Zimbábue
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