Cranial and postcranial anatomy of a juvenile baurusuchid (Notosuchia, Crocodylomorpha) and the taxonomical implications of ontogeny

The Anatomical Record, Год журнала: 2024, Номер unknown

Опубликована: Март 1, 2024

Abstract Baurusuchidae comprises a clade of top‐tier terrestrial predators and are among the most abundant crocodyliforms found in Adamantina Formation, Bauru Basin, Brazil (Campanian‐Maastrichtian). Here, we provide detailed description cranial postcranial osteology myology complete juvenile baurusuchid to date. Although preservation individuals is somewhat rare, previously reported occurrences egg clutches, yearling individual, larger, but skeletally immature specimens, comprise unique opportunity track anatomical changes throughout their ontogenetic series. Its anatomy was resolved with aid three‐dimensional model generated by acquisition computed tomography data, its inferred adductor mandibular musculature compared that mature specimens order assess possible shifts. A subsequent phylogenetic analysis included scoring Gondwanasuchus scabrosus , smallest species known date, evaluate relations relative juvenile. We find considerable differences between juveniles adults concerning skull ornamentation muscle development, which might indicate niche partitioning, also evidence G. corresponds young semaphoront lacking features.

Язык: Английский

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Multiple lines of evidence support anagenesis in Daspletosaurus and cladogenesis in derived tyrannosaurines

Cretaceous Research, Год журнала: 2025, Номер unknown, С. 106080 - 106080

Опубликована: Янв. 1, 2025

Язык: Английский

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The influence of juvenile dinosaurs on community structure and diversity

Science, Год журнала: 2021, Номер 371(6532), С. 941 - 944

Опубликована: Фев. 25, 2021

Despite dominating biodiversity in the Mesozoic, dinosaurs were not speciose. Oviparity constrained even gigantic to less than 15 kg at birth; growth through multiple morphologies led consumption of different resources each stage. Such disparity between neonates and adults could have influenced structure diversity dinosaur communities. Here, we quantified this effect for 43 communities across 136 million years seven continents. We found that megatheropods (more 1000 kg) such as tyrannosaurs had specific effects on community structure. Although herbivores spanned body size range, with lacked carnivores weighing 100 kg. demonstrate juvenile likely filled mesocarnivore niche, resulting reduced overall taxonomic diversity. The consistency pattern suggests ontogenetic niche shift was an important factor generating

Язык: Английский

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Morphology and distribution of scales, dermal ossifications, and other non‐feather integumentary structures in non‐avialan theropod dinosaurs

Biological reviews/Biological reviews of the Cambridge Philosophical Society, Год журнала: 2022, Номер 97(3), С. 960 - 1004

Опубликована: Янв. 6, 2022

ABSTRACT Modern birds are typified by the presence of feathers, complex evolutionary innovations that were already widespread in group theropod dinosaurs (Maniraptoriformes) include crown Aves. Squamous or scaly reptilian‐like skin is, however, considered plesiomorphic condition for theropods and more broadly. Here, we review morphology distribution non‐feathered integumentary structures non‐avialan theropods, covering squamous naked as well dermal ossifications. The record non‐averostran is limited to tracks, which ubiquitously show a tiny reticulate scales on plantar surface pes. This consistent also with younger averostran body fossils, confirm an arthral arrangement digital pads. Among averostrans, confirmed Ceratosauria ( Carnotaurus ), Allosauroidea Allosaurus , Concavenator Lourinhanosaurus Compsognathidae Juravenator Tyrannosauroidea Santanaraptor Albertosaurus Daspletosaurus Gorgosaurus Tarbosaurus Tyrannosaurus whereas ossifications consisting sagittate mosaic osteoderms restricted Ceratosaurus . Naked, non‐scale bearing found contentious tetanuran Sciurumimus ornithomimosaurians Ornithomimus ) possibly tyrannosauroids patagia scansoriopterygids Ambopteryx Yi ). Scales surprisingly conservative among compared some dinosaurian groups (e.g. hadrosaurids); preservation tegument most specimens hinders further interrogation. Scale patterns vary and/or within regions polarised, snake‐like ventral tail latter two genera. Unusual but uniformly distributed patterning occurs feature present only Few currently compelling evidence co‐occurrence feathers Sinornithosaurus although probably retained mani pedes many heavy plumage. Feathers filamentous appear have replaced integuments maniraptorans. Theropod skin, broadly, remains virtually untapped area study appropriation commonly used techniques other palaeontological fields holds great promise future insights into biology, taphonomy relationships these extinct animals.

Язык: Английский

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Taxonomic Status of Nanotyrannus lancensis (Dinosauria: Tyrannosauroidea)—A Distinct Taxon of Small-Bodied Tyrannosaur

Fossil Studies, Год журнала: 2024, Номер 2(1), С. 1 - 65

Опубликована: Янв. 3, 2024

Tyrannosaurs are among the most intensively studied and best-known dinosaurs. Despite this, their relationships systematics highly controversial. An ongoing debate concerns validity of Nanotyrannus lancensis, interpreted either as a distinct genus small-bodied tyrannosaur or juvenile Tyrannosaurus rex. We examine multiple lines evidence show that strongly supports recognition species for following reasons: 1. High diversity tyrannosaurs predatory dinosaurs idea tyrannosaurids inhabited late Maastrichtian Laramidia; 2. lacks characters supporting referral to Tyrannosaurinae but differs from T. rex in >150 morphological characters, while intermediate forms combining features unknown; 3. Histology shows specimens showing (i) skeletal fusions, (ii) mature skull bone textures, (iii) slow growth rates relative rex, (iv) decelerating final years life, (v) curves predicting adult masses ~1500 kg less, these animals subadults young adults, not Tyrannosaurus; 4. series other tyrannosaurids, including Tarbosaurus Gorgosaurus, do changes proposed Nanotyrannus–Tyrannosaurus series, deriving requires several inconsistent with known patterns dinosaur development; 5. Juvenile exist, diagnostic 6. Phylogenetic analysis suggests may lie outside Tyrannosauridae. Tyrannosaur before K-Pg extinction is higher than previously appreciated. The challenges inherent diagnosing based on fossils mean paleontologists be systematically underestimating ancient ecosystems.

Язык: Английский

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A giant tyrannosaur from the Campanian–Maastrichtian of southern North America and the evolution of tyrannosaurid gigantism

Scientific Reports, Год журнала: 2024, Номер 14(1)

Опубликована: Янв. 11, 2024

Abstract Tyrannosaurid dinosaurs dominated as predators in the Late Cretaceous of Laurasia, culminating evolution giant Tyrannosaurus rex , both last and largest tyrannosaurid. Where when Tyrannosaurini ( T. kin) originated remains unclear. Competing hypotheses place tyrannosaurin origins Asia, or western North America (Laramidia). We report a new tyrannosaurin, mcraeensis from Campanian–Maastrichtian Hall Lake Formation New Mexico, based on fossil previously referred to . predates by ~ 6–7 million years, yet rivaled it size. Phylogenetic analysis recovers sister suggests southern Laramidia. Evolution tyrannosaurs America, alongside ceratopsians, hadrosaurs, titanosaurs large-bodied evolved at low latitudes America.

Язык: Английский

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Theropod guild structure and the tyrannosaurid niche assimilation hypothesis: implications for predatory dinosaur macroecology and ontogeny in later Late Cretaceous Asiamerica¹

Canadian Journal of Earth Sciences, Год журнала: 2021, Номер 58(9), С. 778 - 795

Опубликована: Июнь 17, 2021

Well-sampled dinosaur communities from the Jurassic through early Late Cretaceous show greater taxonomic diversity among larger (>50 kg) theropod taxa than of Campano-Maastrichtian, particularly to those eastern/central Asia and Laramidia. The large carnivore guilds in Asiamerican assemblages are monopolized by tyrannosaurids, with adult medium-sized (50–500 predators rare or absent. In contrast, various clades theropods found occupy these body sizes earlier faunas, including tyrannosauroids. Assemblages “missing middle-sized” not have correspondingly sparser potential prey species recorded same faunas. niches Laramidia may been assimilated juvenile subadults tyrannosaurid species, functionally distinct their ecomorphologies. It is speculated that if tyrannosaurids previously occupied mid-sized predators, we would expect evolution transitions morphology possibly delay achievement somatic maturity this taxon.

Язык: Английский

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New spinosaurids from the Wessex Formation (Early Cretaceous, UK) and the European origins of Spinosauridae

Scientific Reports, Год журнала: 2021, Номер 11(1)

Опубликована: Сен. 29, 2021

Spinosaurids are among the most distinctive and yet poorly-known of large-bodied theropod dinosaurs, a situation exacerbated by their mostly fragmentary fossil record competing views regarding palaeobiology. Here, we report two new Early Cretaceous spinosaurid specimens from Wessex Formation (Barremian) Isle Wight. Large-scale phylogenetic analyses using parsimony Bayesian techniques recover pair in clade within Baryonychinae that also includes hypodigm African Suchomimus. Both represent distinct novel taxa, herein named Ceratosuchops inferodios gen. et sp. nov. Riparovenator milnerae A palaeogeographic reconstruction suggests European origin for Spinosauridae, with at least dispersal events into Africa. These finds provide welcome information on poorly sampled areas anatomy, suggest sympatry was present potentially common baryonychines spinosaurids as whole, contribute to updated palaeobiogeographic reconstructions clade.

Язык: Английский

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Forty new specimens of Ichthyornis provide unprecedented insight into the postcranial morphology of crownward stem group birds

PeerJ, Год журнала: 2022, Номер 10, С. e13919 - e13919

Опубликована: Дек. 16, 2022

Ichthyornis has long been recognized as a pivotally important fossil taxon for understanding the latest stages of dinosaur–bird transition, but little significant new postcranial material brought to light since initial descriptions partial skeletons in 19 th Century. Here, we present information on morphology from 40 previously undescribed specimens, providing most complete morphological assessment skeleton date. The includes four partially and numerous well-preserved isolated elements, enabling anatomical observations such muscle attachments Mesozoic euornitheans. Among elements that were unknown or poorly represented , specimens include an almost-complete axial series, hypocleideum-bearing furcula, radial carpal bones, fibulae, tarsometatarsus bearing rudimentary hypotarsus, one first-known nearly three-dimensional sterna avialan. Several pedal phalanges are preserved, revealing remarkably enlarged pes presumably related foot-propelled swimming. Although diagnosable exhibit substantial degree variation, some which may relate ontogenetic changes. Phylogenetic analyses incorporating our data employing alternative datasets recover stemward Hesperornithes Iaceornis line with recent hypotheses regarding topology crownward-most portion avian stem group, establish phylogenetically-defined clade names relevant avialan subclades help facilitate consistent discourse future work. provided by these improves evolution among non-neornithine avialans immediately preceding origin crown group birds.

Язык: Английский

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Biomechanics of juvenile tyrannosaurid mandibles and their implications for bite force: Evolutionary biology

The Anatomical Record, Год журнала: 2021, Номер 305(2), С. 373 - 392

Опубликована: Фев. 15, 2021

The tyrannosaurids are among the most well-studied dinosaurs described by science, and analysis of their feeding biomechanics allows for comparison between established tyrannosaurid genera across ontogeny. 3D finite element (FEA) was used to model quantify mechanical properties mandibles (lower jaws) three tyrannosaurine different sizes. To increase evolutionary scope context results, a broader sample validated 2D mandible FEA enabled comparisons ontogenetic stages Tyrannosaurus rex other large theropods. It found that small juvenile subadult tyrannosaurs experienced lower stress overall because muscle forces were relatively lower, but greater simulated stresses at decreasing sizes when specimen force is normalized. strain on post-dentary ligaments decreases in posterior region dentary where teeth impacted food. Tension from lateral insertion looping m. ventral pterygoid increases compressive angular may decrease anterior bending mandible. Low mid-mandible congruent with ultra-robust high bite adult T. rex. Mandible strength size through ontogeny phylogenetically tyrannosaurids, addition exceed theropods equivalent ramus length. These results indicate separate predatory strategies mature tyrannosaurids; lacked bone-crunching specimens hunted smaller prey, while fed larger prey.

Язык: Английский

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