Assessing ontogenetic maturity in extinct saurian reptiles

Biological reviews/Biological reviews of the Cambridge Philosophical Society, Journal Year: 2020, Volume and Issue: 96(2), P. 470 - 525

Published: Dec. 2, 2020

ABSTRACT Morphology forms the most fundamental level of data in vertebrate palaeontology because it is through interpretations morphology that taxa are identified, creating basis for broad evolutionary and palaeobiological hypotheses. Assessing maturity one basic aspects morphological interpretation provides means to study evolution ontogenetic changes, population structure palaeoecology, life‐history strategies, heterochrony along lineages would otherwise be lost time. Saurian reptiles (the least‐inclusive clade containing Lepidosauria Archosauria) have remained an incredibly diverse, numerous, disparate their ~260‐million‐year history. Because great disparity this group, assessing saurian difficult, fraught with methodological terminological ambiguity. We compiled a novel database literature, assembling >900 individual instances assessment, examine critically how has been diagnosed. review often inexact inconsistent terminology used assessment (e.g. ‘juvenile’, ‘mature’) provide routes better clarity cross‐study coherence. describe various methods assess every major integrating from both extant extinct give full account current state field providing method‐specific pitfalls, best practices, fruitful directions future research. recommend new standard subsection, ‘Ontogenetic Assessment’, added Systematic Palaeontology portions descriptive studies explicit diagnoses clear criteria. utility different criteria highly subclade dependent among saurians, even widely neurocentral suture fusion), we phylogenetic context, preferably form bracket, justify use method. Different should conjunction as independent lines evidence when maturity, instead diagnosis resting entirely on single criterion, which common literature. Critically, there need well‐represented growth series integrated fossil record ground assessments well‐constrained, empirically tested methods.

Language: Английский

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The phylogenetic nomenclature of ornithischian dinosaurs

PeerJ, Journal Year: 2021, Volume and Issue: 9, P. e12362 - e12362

Published: Dec. 9, 2021

Ornithischians form a large clade of globally distributed Mesozoic dinosaurs, and represent one their three major radiations. Throughout evolutionary history, exceeding 134 million years, ornithischians evolved considerable morphological disparity, expressed especially through the cranial osteodermal features most distinguishable representatives. The nearly two-century-long research history on has resulted in recognition numerous diverse lineages, many which have been named. Following formative publications establishing theoretical foundation phylogenetic nomenclature throughout 1980s 1990s, proposed names ornithischian clades were provided with definitions. Some these definitions proven useful not changed, beyond way they formulated, since introduction. names, however, multiple definitions, making application ambiguous. Recent implementation International Code Phylogenetic Nomenclature ( ICPN , or PhyloCode ) offers opportunity to explore utility previously established taxon names. Since Articles are be applied retroactively, all published prior its remain informal (and ineffective) light Code. Here, we revise dinosaur clades; revisit 76 preexisting review recent historical use, formally establish Additionally, introduce five new names: two for robustly supported later-diverging hadrosaurids ceratopsians, uniting heterodontosaurids genasaurs, nodosaurids. Our study marks key step towards formal dinosaurs.

Language: Английский

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Osteohistological insight into the growth dynamics of early dinosaurs and their contemporaries

PLoS ONE, Journal Year: 2024, Volume and Issue: 19(4), P. e0298242 - e0298242

Published: April 3, 2024

Dinosauria debuted on Earth’s stage in the aftermath of Permo-Triassic Mass Extinction Event, and survived two other Triassic extinction intervals to eventually dominate terrestrial ecosystems. More than 231 million years ago, Upper Ischigualasto Formation west-central Argentina, dinosaurs were just getting warmed up. At this time, represented a minor fraction ecosystem diversity. Members tetrapod clades, including synapsids pseudosuchians, shared convergently evolved features related locomotion, feeding, respiration, metabolism could have risen later dominance. However, it was that radiated Mesozoic most significantly terms body size, diversity, global distribution. Elevated growth rates are one adaptations set apart, particularly from their contemporary crocodilian mammalian compatriots. When did elevated first evolve? How strategies earliest known compare with those tetrapods ecosystems? We studied femoral bone histology an array early alongside non-dinosaurian contemporaries order test whether oldest exhibited novel strategies. Our results indicate vertebrate fauna collectively exhibits relatively high rates. Dinosaurs among fastest growing taxa sample, but they occupied niche crocodylomorphs, archosauriformes, large-bodied pseudosuchians. Interestingly, these grew at least as quickly, more continuously sauropodomorph theropod Mesozoic. These data suggest that, while ancestral for likely played significant role dinosaurs’ ascent within ecosystems, not them apart contemporaries.

Language: Английский

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The last giants: New evidence for giant Late Triassic (Rhaetian) ichthyosaurs from the UK

PLoS ONE, Journal Year: 2024, Volume and Issue: 19(4), P. e0300289 - e0300289

Published: April 17, 2024

Giant ichthyosaurs with body length estimates exceeding 20 m were present in the latest Triassic of UK. Here we report on discovery a second surangular from lower jaw giant ichthyosaur Somerset, The new find is comparable size and morphology to specimen Lilstock, described 2018, but it more complete better preserved. Both finds are uppermost Westbury Mudstone Formation (Rhaetian), comes Blue Anchor, approximately 10 km west along coast Lilstock. would have been >2 long, an individual estimated at ~25 m. identification two specimens same unique geologic age geographic location warrants erection genus species, Ichthyotitan severnensis gen. et sp. nov. Thin sections revealed histological features already observed similar ichthyosaurian specimens. Our data also supports previous suggestion atypical osteogenesis jaws ichthyosaurs. geological suggest shastasaurid affinities, material too incomplete for definitive referral. nov., first-named Rhaetian probably represents largest marine reptile formally described.

Language: Английский

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Intraskeletal histovariability and skeletochronology in an ornithopod dinosaur from the Maestrazgo Basin (Teruel, Spain)

Journal of Anatomy, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 28, 2025

Abstract Ornithopods are an extinct group of dinosaurs that were particularly abundant and diverse in the Cretaceous Iberian Peninsula, whose abundance Maestrazgo Basin has allowed numerous taxa to be identified over last decade. Many these fossil remains still taxonomically indeterminate require a more detailed study on both macroscopic microscopic scale. In this contribution, osteohistological analysis is carried out partial skeleton—composed five incomplete vertebrae, two dorsal ribs, ischium, fibula, tibia—found province Aliaga (Teruel, NE Spain). We progressive slowdown tissue apposition variation type growth marks generated every bone, allowing precise identification ontogenetic stage specimen as subadult individual. The skeletochronological correlation between different elements also suggests reached sexual maturity at around seven years age died nine twelve age. Likewise, usefulness three‐front model proven for first time ornithopod dinosaur, tool analysing histology expressed by bone single inferring their potential. Comparison with other reveals great variability each element shows depending taxon analysed, which prevents us from determining suitable studying skeletochronology any taxon.

Language: Английский

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Exploring the ceratopsid growth record: A comprehensive osteohistological analysis of Triceratops (Ornithischia: Ceratopsidae) and its implications for growth and ontogeny

Cretaceous Research, Journal Year: 2023, Volume and Issue: 154, P. 105738 - 105738

Published: Oct. 7, 2023

Language: Английский

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The osteohistology of new remains of Pararhabdodon isonensis sheds light into the life history and paleoecology of this enigmatic European lambeosaurine dinosaur

Cretaceous Research, Journal Year: 2020, Volume and Issue: 118, P. 104677 - 104677

Published: Oct. 15, 2020

Language: Английский

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Dinosaur senescence: a hadrosauroid with age-related diseases brings a new perspective of “old” dinosaurs

Scientific Reports, Journal Year: 2021, Volume and Issue: 11(1)

Published: June 11, 2021

Abstract Senile vertebrates are extremely rare in the fossil record, making their recognition difficult. Here we present largest known representative of Late Cretaceous hadrosauriform Gobihadros mongoliensis showing features cessation growth indicating attainment terminal size. Moreover, this is first non-avian dinosaur with an age-related pathology recognized as primary calcium pyrophosphate deposition disease its advanced age. Because senile dinosaurs so and thus “senescence” unclear, also propose a new unified definition dinosaur: individual which achieved size revealed by presence external fundamental system closed transcortical channels, has completely secondary remodeled weight-bearing bones possesses non-traumatic, non-contagious bone pathologies correlated

Language: Английский

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Ontogeny and variation in the skull roof and braincase of Maiasaura peeblesorum from the Two Medicine Formation of Montana, U.S.A.

Acta Palaeontologica Polonica, Journal Year: 2021, Volume and Issue: 66

Published: Jan. 1, 2021

Five new partial skulls of the hadrosaurid dinosaur Maiasaura peeblesorum from Linster Quarry bone bed (Two Medicine Formation, Campanian) in Montana, USA, provide basis for a description skull roof and braincase morphology this taxon.These additionally form an ontogenetic series consisting one subadult, two small "intermediate adults", larger "mature adults".The subadult is approximately thirds as wide largest adult lacks nasofrontal crest, suggesting that crest formed relatively late ontogeny compared to some other hadrosaurids.As closely related taxa, M. have proportionately wider larger, more rugosely ridged contact supporting crest.In adults, incipiently overhangs anterior margin dorsotemporal fenestrae.In examined, semicircular view incorporates flared, anteriorly concave prefrontals its lateral margins.Intraspecific variation observed cranial characters previously discussed interspecific including prominence dorsal depressions on frontal, position foramen facial nerve (CN VII).Although shares trends with Brachylophosaurus Probrachylophosaurus, it deviates ways previous heterochronic model proposed evolution Maiasaurini.

Language: Английский

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New data on high-latitude hadrosaurid dinosaurs from the Upper Cretaceous Kakanaut Formation of Chukotka, Russia

Cretaceous Research, Journal Year: 2023, Volume and Issue: 149, P. 105552 - 105552

Published: April 11, 2023

Language: Английский

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