Assessing ontogenetic maturity in extinct saurian reptiles

Biological reviews/Biological reviews of the Cambridge Philosophical Society, Год журнала: 2020, Номер 96(2), С. 470 - 525

Опубликована: Дек. 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.

Язык: Английский

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Growth variability, dimensional scaling, and the interpretation of osteohistological growth data

Biology Letters, Год журнала: 2021, Номер 17(11)

Опубликована: Ноя. 1, 2021

Osteohistological data are commonly used to study the life history of extant and extinct tetrapods. While recent advances have permitted detailed reconstructions growth patterns, physiology other features using these data, they most in assessments ontogenetic stage relative animals. These methods seen widespread adoption years, rapidly becoming a common component taxonomic description new fossil taxa, but often applied without close consideration sources variation present or dimensional scaling relationships that exist among different osteohistological measurements. Here, we use combination theoretical models empirical from range tetrapods review variability measurements, their resulting interpretations can be made those data. In particular, provide recommendations on usage interpretation mark spacing/zonal thickness when likely unreliable, under what conditions useful inferences for studies history.

Язык: Английский

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Ontogenetic and interelemental study of appendicular bones of Caiman latirostris Daudin, 1802 sheds light on osteohistological variability in crocodylians

Journal of Morphology, Год журнала: 2024, Номер 285(4)

Опубликована: Апрель 1, 2024

Abstract The osteohistology of vertebrates provides a reliable source to deduce biological information, particularly regarding growth and development. Although osteohistological studies in Neosuchia (Crocodyliformes, Mesoeucrocodylia) are relatively numerous, the number species studied within group is still small. Extant crocodilians known exhibit intraspecific variability linked environmental conditions, habitat, feeding, other intrapopulation factors. Here, we analyzed living South American Caiman latirostris throughout posthatching ontogeny. histology several appendicular bones 13 different‐sized captive wild individuals were examined. some thin sections revealed classic lamellar, parallel‐fibered, or woven bone matrices, others showed variation mix between organization tissue. These histological differences likely related dynamics caimans. In juveniles studied, remnants embryonic observed. Osteohistological prevailing conditions documented. Furthermore, our results show ontogenetic type tissues deposited development C. . This study offers broad framework for life history interpretations insight into evolutionary extinct crocodylian lineages.

Язык: Английский

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Extreme growth plasticity in the early branching sauropodomorph Massospondylus carinatus

Biology Letters, Год журнала: 2021, Номер 17(5)

Опубликована: Май 1, 2021

There is growing evidence of developmental plasticity in early branching dinosaurs and their outgroups. This reflected disparate patterns morphological histological change during ontogeny. In fossils, only the osteohistological assessment annual lines arrested growth (LAGs) can reveal pace skeletal growth. Some later non-bird dinosaur species appear to have followed an asymptotic pattern, with declining rates at increasing ontogenetic ages. By contrast, sauropodomorph Plateosaurus trossingensis appears had plastic growth, suggesting that this was plesiomorphic condition for dinosaurs. The South African Massospondylus carinatus ideal taxon which test because it known from a comprehensive series, has recently been stratigraphically taxonomically revised, lived time ecosystem upheaval following end-Triassic extinction. Here, we report on results femoral study M. comprising 20 individuals ranging embryo skeletally mature. We find major variability spacing LAGs infer body masses given ages, contradicting previous studies. These findings are consistent high degree carinatus.

Язык: Английский

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The evolution of larvae in temnospondyls and the stepwise origin of amphibian metamorphosis

Biological reviews/Biological reviews of the Cambridge Philosophical Society, Год журнала: 2024, Номер 99(5), С. 1613 - 1637

Опубликована: Апрель 10, 2024

ABSTRACT The question of what the ancient life cycle tetrapods was like forms a key component in understanding origin land vertebrates. existence distinct larval forms, as exemplified by many lissamphibians, and their transformation into adults is an important aspect this field. temnospondyls, largest clade Palaeozoic–Mesozoic non‐amniote tetrapods, covered wide ecomorphological range from fully aquatic to terrestrial taxa. In various species, rich ontogenetic data have accumulated over past 130 years, permitting study early phases temnospondyl development. eight been identified which skeleton formed. branchiosaurids eryopiform Sclerocephalus , large parts ossification sequence are now known. Most taxa small specimens preserved had larvae with external gills that superficially resemble salamanders. edopoids, dvinosaurs, eryopiforms, developed slowly, incompletely ossified axial appendicular skeletons, but possessed fast‐developing dermal skull strong teeth. Irrespective adult terrestriality or life, there no drastic during later ontogeny, slow steady acquisition features. dissorophoids, limbs at much faster pace, whereas formation slowed down, especially amphibamiforms, culminating neotenic Branchiosauridae. zatracheid Acanthostomatops profound led adult. basal dissorophoid Stegops retained rapid development bones established dentigerous, strongly palate early. Micromelerpeton last slightly delayed metamorphosis remained long phase morphological transformations. became more drastic, increasing number events packed short ontogeny. This Apateon Platyrhinops Amphibamus condensation maximised. We distinguish three different types (morphological, ecological drastic) evolved cumulatively within temnospondyls.

Язык: Английский

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Histological skeletochronology indicates developmental plasticity in the early Permian stem lissamphibian Doleserpeton annectens

Ecology and Evolution, Год журнала: 2020, Номер 10(4), С. 2153 - 2169

Опубликована: Фев. 1, 2020

Doleserpeton annectens is a small-bodied early Permian amphibamiform, clade of temnospondyl amphibians regarded by many workers to be on the lissamphibian stem. Most studies this taxon have focused solely its anatomy, but further exploration other aspects paleobiology, such as developmental patterns, critical for better understanding evolutionary history lissamphibians. Here, we present histological analysis growth patterns in D. that utilizes 60 femora, largest sample size any Paleozoic tetrapod. We identified pervasive pairs closely spaced lines arrested (LAGs), pattern indicates marked degree climatic harshness and would result two cessations within presumed single year. documented wide variation compared previous skeletochronological studies, reflected poor correlation between inferred age, observation aligns with observed extant Furthermore, sensitivity analyses conducted subsampling our dataset at more typical sizes paleontological produced range results. This includes biologically improbable results exceptionally well-fit curves demonstrate low can produce potentially misleading artifacts. propose weak age represents plasticity typifies Detection these likely only possible large extinct taxa, false, warrant caution drawing paleobiological interpretations from samples.

Язык: Английский

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The paleobiology and paleoecology of South African Lystrosaurus

PeerJ, Год журнала: 2020, Номер 8, С. e10408 - e10408

Опубликована: Ноя. 24, 2020

Lystrosaurus was one of the few tetrapods to survive end-Permian mass extinction (EPME), most catastrophic biotic crisis in Phanerozoic history. The significant increased abundance this genus during post-extinction Early Triassic recovery period has made an iconic survivor taxon globally and ideal for studying changes growth dynamics a extinction. There is potential evidence Lilliput effect South Africa as two species that became highly abundant after EPME are relatively smaller than Permian species. In order test hypothesis detailed examination body size life history Permo-Triassic required. study, basal skull length patterns four African from Karoo Basin, L. maccaigi, curvatus, murrayi declivis, were examined using cranial measurements bone histology. show supports previous studies. osteohistology all reveal rapidly forming fibrolamellar tissues early mid-ontogeny. Growth marks common maccaigi but rare inconsistent purely declivis. inconsistency these latter taxa suggests presence developmental plasticity. This feature may have been advantageous allowing alter their response environmental cues climate. An overall transition slower parallel-fibered observed largest individuals absent limb bones other absence such tissue or outer circumferential lamellae declivis indicates even collected specimens do not represent fully grown individuals. Although size, lack asymptote adult would notably larger similar large curvatus when grown. Thus, previously described effect, recognized by some authors fossil record (such therocephalian Moschorhinus kitchingi), be product high juvenile excess mortality rather strict "dwarfing" lifestyle also re-examined. studies proposed aquatic genus, morphology microanatomy several terrestrial dicynodonts mode life.

Язык: Английский

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Anatomy and revised diagnosis of the embolomere Calligenethlon watsoni from Joggins, Nova Scotia, based on micro-computed tomography

Zoological Journal of the Linnean Society, Год журнала: 2025, Номер 203(2)

Опубликована: Янв. 30, 2025

Abstract Although Calligenethlon watsoni, an enigmatic embolomere from Joggins, Nova Scotia, has been known since 1934, in-depth description of its anatomy (including CT data) and updated taxonomic diagnosis yet to be completed. Additionally, subsequently discovered specimens have referred the taxon simply if they display traits. As a result, is represented by collection united on basis largely non-diagnostic Here, exquisitely preserved specimen identified as Calligenethlon, NSM 994GF1.1, described in detail using micro-computed tomography. Comparison this holotype supports referral anatomical knowledge gained here allows for generation more robust morphological genus Calligenethlon. We then re-evaluate all other determine which are consistent with their taxon, inconclusively taxon. These data discussed provide new insights into diversity embolomeres at Joggins’ locality.

Язык: Английский

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Osteohistology of a Triassic dinosaur population reveals highly variable growth trajectories typified early dinosaur ontogeny

Scientific Reports, Год журнала: 2022, Номер 12(1)

Опубликована: Окт. 15, 2022

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

Язык: Английский

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Long Bone Morphology and Histology of the Stem Salamander Kulgeriherpeton ultimum (Caudata, Karauridae) from the Lower Cretaceous of Yakutia

Paleontological Journal, Год журнала: 2024, Номер 58(1), С. 101 - 111

Опубликована: Фев. 1, 2024

Язык: Английский

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