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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Morphology, development and ecological implications of the dentition of Bajadasaurus pronuspinax

Historical Biology, Год журнала: 2025, Номер unknown, С. 1 - 21

Опубликована: Март 11, 2025

Язык: Английский

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Ontogenetic Changes in Endocranial Anatomy in Gorgosaurus libratus (Theropoda: Tyrannosauridae) Provide Insight Into the Evolution of the Tyrannosauroid Endocranium

The Journal of Comparative Neurology, Год журнала: 2025, Номер 533(5)

Опубликована: Апрель 28, 2025

ABSTRACT Over the past two decades, increased accessibility to computed tomography (CT) scanners has greatly facilitated documentation of endocranium in numerous extinct theropod taxa. However, most these studies have focused on morphology mature individuals, thus changes or variation through ontogeny theropods remains largely unknown. The current study sheds light endocranial anatomy eutyrannosaurian tyrannosauroid, Gorgosaurus libratus , both an ontogenetic and evolutionary context. Based CT scans six braincases, including those recently discovered juvenile we virtually reconstruct describe for a growth series G. . Despite considerable skull architecture, relatively few occurred These include subtle increase length hindbrain region endocast inflation tympanic sinus diverticula adults relative juveniles. Among significant is decrease distinctiveness brain endocasts as mature. exhibit better defined cerebral hemispheres, optic lobes, cerebella than larger more individuals. This suggests closer correspondence between tyrannosaurids, indicating individuals provides accurate representation structure its regions displays mix basal archosaurian traits derived coelurosaurian traits. More primitive features large olfactory bulbs tracts, posteroventrally oriented long axis cerebrum, posteriorly positioned whereas prominent flexure, somewhat enlarged cerebellum that at least partially separates left right lobes. An understanding acquisition such leading avian may be further elucidated via (more reflective structure/organization various regions) earlier‐diverging (e.g., Allosauroidea, Megalosauroidea, Coelophysoidea).

Язык: Английский

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A New Furileusaurian Abelisaurid from La Invernada (Upper Cretaceous, Santonian, Bajo De La Carpa Formation), Northern Patagonia, Argentina

Journal of Vertebrate Paleontology, Год журнала: 2021, Номер unknown, С. e1877151 - e1877151

Опубликована: Март 30, 2021

Abelisaurids are among the most abundant and diverse Patagonian Late Cretaceous theropods. Here, we present a new furileusaurian abelisaurid, Llukalkan aliocranianus gen. et sp. nov., represented by cranial remains from Bajo de la Carpa Formation (Santonian) at La Invernada fossil area, northwestern Patagonia. Features characterizing this taxon include possible caudal tympanic recess posterior to columellar recess, T-shaped lacrimal with jugal ramus lacking suborbital process, large foramina for middle cerebral veins widely separated median supraoccipital crest. In addition this, bulge on anteromedial border of supratemporal fossa, tall posteriorly projected paroccipital processes, basal tubera interconnected distally, triangular basisphenoid single foramen sphenoidal artery basisphenoid, differentiate Viavenator exxoni. The latter is other same area stratigraphic unit. Although holotype probably corresponds sub-adult—as morphology suggests— possibility that it represents juvenile V. exxoni discarded based mainly presence (which absent in exxoni). probable coexistence two abelisaurid taxa demonstrates abelisaurids were one important—and likely main—predator component ecosystems, not only but also all Patagonia, during Cretaceous.

Язык: Английский

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Mandibular force profiles and tooth morphology in growth series of Albertosaurus sarcophagus and Gorgosaurus libratus (Tyrannosauridae: Albertosaurinae) provide evidence for an ontogenetic dietary shift in tyrannosaurids¹

Canadian Journal of Earth Sciences, Год журнала: 2021, Номер 58(9), С. 812 - 828

Опубликована: Янв. 26, 2021

The albertosaurines Albertosaurus sarcophagus and Gorgosaurus libratus are among the best represented tyrannosaurids, known from nearly complete growth series. These specimens provide an opportunity to study mandibular biomechanical properties tooth morphology infer changes in feeding behaviour bite force through ontogeny tyrannosaurids. Mandibular profiles reveal that symphyseal region of is consistently stronger bending than mid-dentary region, indicating anterior extremity jaws played important role prey capture handling ontogeny. was better adapted withstand torsional stresses most non-avian theropods, but not extent seen Tyrannosaurus rex, suggesting albertosaurine may have involved less bone crushing or perhaps relatively smaller rex. constancy these at all stages indicates although maintained a similar strategy ontogeny, size/type had change between juvenile mature individuals. This ontogenetic dietary shift likely happened when individuals reached length ∼58 cm, size which teeth ziphodont incrassate shape begins increase exponentially. fact large were capable generating forces equivalent similar-sized tyrannosaurines suggests no significant differences jaw-closing musculature existed two clades powerful rex result its body rather unique adaptations related specialized ecology.

Язык: Английский

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Morphology of the temporal skull region in tetrapods: research history, functional explanations, and a new comprehensive classification scheme

Biological reviews/Biological reviews of the Cambridge Philosophical Society, Год журнала: 2021, Номер 96(5), С. 2229 - 2257

Опубликована: Май 31, 2021

The morphology of the temporal region in tetrapod skull traditionally has been a widely discussed feature vertebrate anatomy. evolution different openings Amniota (mammals, birds, and reptiles), Lissamphibia (frogs, salamanders, caecilians), several extinct groups sparked debates on phylogenetic, developmental, functional background this skull. This led most famously to erection amniote taxa based number position fenestrae their skulls. However, these are no longer recognised represent natural groupings is not necessarily an adequate trait for use reconstruction phylogenies. Yet, new fossil finds, notably parareptiles stem-turtles, as well modern embryological biomechanical studies continue provide insights into morphological diversity region. Here, we introduce novel comprehensive classification scheme various morphotypes all Tetrapoda that independent phylogeny previous terminology may facilitate comparisons future studies. We then review history research document how, from early 19th century with first recognition differences proposals phylogenetic relationships assessment over centuries, perspective developed, highlight controversies still remain. also compare developmental drivers proposed observed how effects internal external factors structure have interpreted.

Язык: Английский

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The rostral neurovascular system of Tyrannosaurus rex

Palaeontologia Electronica, Год журнала: 2022, Номер unknown

Опубликована: Янв. 1, 2022

The study of the rostral neurovascular system using CT scanning has shed new light on phylogenetic and palaeobiological reconstructions many extinct tetrapods.This research shows a detailed description canals Tyrannosaurus rex including nasal, maxillary (dorsal alveolar), mandibular (ventral alveolar) canals.Extensive comparisons with published descriptions show that pattern these in is not unusual for non-avian theropod.As theropod Neovenator, canal several anastomoses its branches.Differences from plesiomorphic sauropsid condition are concentrated within neurovasculature, which primitively horizontal, tubular, connected to single row supralabial foramina, whereas main trunk oriented more obliquely dorsally displaced give room deep tooth alveolae.As result, lateral branches provide innervation blood supply skin dorsoventrally elongated compared non-theropod taxa, multiple rows foramina present.An overview literature suggests evolution trigeminal among sauropsids only weakly supports previous hypotheses crocodile-like facial sensitivity theropods (except, maybe, semiaquatic taxa).More systematic studies may help answer question whether lips were present or not.

Язык: Английский

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Exceptionally preserved stomach contents of a young tyrannosaurid reveal an ontogenetic dietary shift in an iconic extinct predator

Science Advances, Год журнала: 2023, Номер 9(49)

Опубликована: Дек. 8, 2023

Tyrannosaurids were large carnivorous dinosaurs that underwent major changes in skull robusticity and body proportions as they grew, suggesting occupied different ecological niches during their life span. Although adults commonly fed on dinosaurian megaherbivores, the diet of juvenile tyrannosaurids is largely unknown. Here, we describe a remarkable specimen Gorgosaurus libratus preserves articulated hindlimbs two yearling caenagnathid inside its abdominal cavity. The prey selectively dismembered consumed separate feeding events. This predator-prey association provides direct evidence an ontogenetic dietary shift tyrannosaurids. Juvenile individuals may have hunted small young until reached size when, to satisfy energy requirements, transitioned megaherbivores. both mesopredator apex predator roles span, factor been key evolutionary success.

Язык: Английский

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How smart was T. rex? Testing claims of exceptional cognition in dinosaurs and the application of neuron count estimates in palaeontological research

The Anatomical Record, Год журнала: 2024, Номер 307(12), С. 3685 - 3716

Опубликована: Апрель 26, 2024

Recent years have seen increasing scientific interest in whether neuron counts can act as correlates of diverse biological phenomena. Lately, Herculano-Houzel (2023) argued that fossil endocasts and comparative neurological data from extant sauropsids allow to reconstruct telencephalic Mesozoic dinosaurs pterosaurs, which might proxies for behaviors life history traits these animals. According this analysis, large theropods such Tyrannosaurus rex were long-lived, exceptionally intelligent animals equipped with "macaque- or baboon-like cognition", whereas sauropods most ornithischian would displayed significantly smaller brains an ectothermic physiology. Besides challenging established views on dinosaur biology, claims raise questions count estimates could benefit research general. Here, we address findings by revisiting Herculano-Houzel's work, identifying several crucial shortcomings regarding analysis interpretation. We present revised encephalization dinosaurs, derive phylogenetically informed modeling amended dataset endocranial measurements. For large-bodied particular, recover lower than previously proposed. Furthermore, review the suitability variables numbers relative brain size predict cognitive complexity, metabolic rate coming conclusion they are flawed Instead relying when reconstructing argue integrative studies needed approach complex subject.

Язык: Английский

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Absolute abundance and preservation rate of Tyrannosaurus rex

Science, Год журнала: 2021, Номер 372(6539), С. 284 - 287

Опубликована: Апрель 15, 2021

Estimating dinosaur abundance the of a species is common practice for extant and can reveal many aspects its ecology, evolution, threat level. that are extinct, especially those long much trickier endeavor. Marshall et al. used relationship established between body size population density in to estimate traits such as density, distribution, total biomass, persistence one best-known dinosaurs, Tyrannosaurus rex , revealing previously hidden ecology. Science this issue p. 284

Язык: Английский

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