Evolution of growth strategy in alligators and caimans informed by osteohistology of the late Eocene early‐diverging alligatoroid crocodylian Diplocynodon hantoniensis

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

Published: Feb. 9, 2025

Among living crocodylians, alligatoroids exhibit a wide range of body sizes and biogeographic distribution that spans tropical-to-subtropical climates. The fossil record alligatoroids, however, reveals even greater diversity, including multiple examples gigantism broader extends into polar latitudes. Osteohistological studies on extant show alligators caimans both seasonal growth, with roughly comparable growth rates. However, diverged from one another over 60 million years ago; the dearth extinct makes it unclear if shared condition in taxa reflects convergent responses to rapid climatic changes recent past or represents ancestral alligatoroids. Additionally, sample are often limited two individuals, especially obscuring any intraspecific variation present. To address this uncertainty, we conducted largest monospecific osteohistological study an crocodylian date, based nine femora, providing unique insight early-diverging alligatoroid Diplocynodon hantoniensis late Eocene UK. bone microanatomy D. shows moderate compactness, well-defined medullary cavity, features generally consistent those Samples vary greatly along continuum degree remodelling vascularity, highlighting importance evaluating limitations basing histological assessments singleton samples. Ontogenetic assessment indicates our captures skeletally immature mature approximately corresponding femoral size, but notable exceptions possibly driven by sexual dimorphism. Body size estimates for (1.2-3.4 m) fall within typical American (Alligator mississippiensis). Reconstruction cyclical marks similar overall rate between A. mississippiensis. As more generally, is determinate, seasonally-controlled growth. Femoral circumference scales positively length hantoniensis, demonstrating allometry This differs some other crocodylians (e.g. Crocodylus niloticus johnstoni) suggests conservation allometric relationships in-depth look early diverging seasonality rates present members were established near base clade. Furthermore, highlights larger samples singular species order capture potential when making clade-wide interpretations.

Language: Английский

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Osteohistological analysis of metatarsals reveals new information on pathology and life history of troodontids from the Campanian Dinosaur Park Formation, Alberta, Canada

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

Published: April 19, 2025

Abstract Troodontidae is a family of small‐bodied theropods known predominantly from Asia but are comparatively scarce in North America. In the Dinosaur Park Formation (DPF) Alberta, Canada, they isolated material, precluding taxonomic and ontogenetic precision for this clade. Previously never sampled histologically within DPF, here we attempt to fill gaps our knowledge about life histories clade formation by surveying metatarsals, which among most abundant identifiable troodontid elements DPF. We 11 metatarsals (three metatarsal IIs, three IIIs five IVs) varying sizes included pathological individuals describe microanatomy both healthy determine status each element graph their pattern growth. Osteohistology reveals that grew remodelled asymmetrically cortex, ceasing growth remodelling primarily along articular surfaces entheses. Pathological ranged displaying features response localised stress (chronic callus avulsion/chip fracture) extreme modification trauma inflammation at distal joint. Only latter appeared be related overall growth, suggesting condition either developed early stunted or another underlying cause was responsible resulting observed. Overall, tracking specimens there least two trajectories DPF differentiated timing major spurts plateaus. Whether represents sexual dimorphism, diversity, form variation warrants further investigation.

Language: Английский

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Palaeobiological inferences of the aetosaur Aetosauroides scagliai (Archosauria: Pseudosuchia) based on microstructural analyses of its appendicular bones

Historical Biology, Journal Year: 2022, Volume and Issue: 35(3), P. 303 - 314

Published: Feb. 26, 2022

Aetosaurs were a group of armoured pseudosuchians, recorded in most the Upper Triassic continental deposits worldwide. Several osteohistological contributions aetosaurs focused on their osteoderms, but rarely appendicular bones. Here, we analyse microstructure humerus, femur and tibia Aetosauroides scagliai (specimens PVL 2073 [holotype] 2052). These exhibit cortical bone formed by highly vascularised fibrolamellar present inner portion cortex, mixed with scarce parallel-fibred bone. Also, they show outermost cortex. A general growth pattern that includes first rapid stage followed slow is reported. Nevertheless, rate presence embedded layers recognise more variation within Aetosauria. The value bones osteoderms as age estimators variable, being useful early stages, late stages are better (based particular osteoderms). Through morphological (neurocentral sutures) histological (EFS absent) information, holotype (PVL 2073) was recovered between juvenile subadult stages. Using statistical model combines microanatomical data, terrestrial lifestyle inferred for Aetosauroides, which concur previous analyses.

Language: Английский

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

Scientific Reports, Journal Year: 2022, Volume and Issue: 12(1)

Published: Oct. 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.

Language: Английский

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Palaeobiological inferences of “rauisuchians” Fasolasuchus tenax (Los Colorados Fm., Argentina) and Prestosuchus chiniquensis (Santa Maria Super sequence, Brazil) from the Middle–Upper Triassic of South America based on microstructural analyses

Journal of Anatomy, Journal Year: 2023, Volume and Issue: 243(6), P. 893 - 909

Published: July 31, 2023

"Rauisuchia" is a non-monophyletic group of quadrupedal and carnivorous pseudosuchians that inhabited the entire world during Middle-Upper Triassic period (Anisian/Ladinian-Rhaetian). In South America, "rauisuchians" reached largest sizes among continental carnivores. Despite their important ecological role, some aspects palaeobiology have been poorly examined. Here, we study appendicular bones, dorsal ribs osteoderms two genera, Argentinean Fasolasuchus tenax (PVL 3850, holotype) Brazilian Prestosuchus chiniquensis (SNSB-BSPG AS XXV) respectively. The femur F. formed by laminar fibrolamellar bone, which composed non-fully monorefringent woven-fibred matrix primary osteons; rib has Haversian bone composition with an external fundamental system recorded osteoderm well-organised parallel-fibred bone. femur, humerus fibula P. are mostly strongly arranged vascularisation. minimal ages obtained correspond to 9 years for (based on maximum number growth marks in osteoderm) 4 (obtained from highest count humerus). attained somatic skeletal maturity, while was near reaching sexual but it somatically immature. overall rapid rate high uniform vascularisation seems imply these features common most "rauisuchians", except chiniquensis.

Language: Английский

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Comptonatus chasei , a new iguanodontian dinosaur from the Lower Cretaceous Wessex Formation of the Isle of Wight, southern England

Journal of Systematic Palaeontology, Journal Year: 2024, Volume and Issue: 22(1)

Published: July 9, 2024

A new iguanodontian dinosaur, Comptonatus chasei gen. et sp. nov., is described from the Lower Cretaceous Wessex Formation of Isle Wight. These strata provide an important record a critical time in development diversity. The specimen, which here for first time, was found and excavated 2013 represents most complete skeleton discovered Wealden Group century. taxon diagnosed by several autapomorphies neurocranium, teeth, coracoid other parts body, together with unique suite characters. include dentary straight ventral border, markedly expanded prepubic blade. features set it apart sympatric Mantellisaurus atherfieldensis, Brighstoneus simmondsi Iguanodon cf. bernissartensis, increasing known diversity this clade Barremian–early Aptian England. http://zoobank.org/urn:lsid:zoobank.org:pub:2F3125A5-BDEF-4835-8829-92104752A86F

Language: Английский

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Fossil bone histology reveals ancient origins for rapid juvenile growth in tetrapods

Communications Biology, Journal Year: 2022, Volume and Issue: 5(1)

Published: Nov. 28, 2022

Patterns of growth throughout the lifetime an animal reflect critical life history traits such as reproductive timing, physiology, and ecological interactions. The ancestral pattern for tetrapods has traditionally been described slow-to-moderately paced, akin to modern amphibians, with fast high metabolic rates considered a specialized physiological trait amniotes. Here, we present bone histology from ontogenetic series Early Carboniferous stem tetrapod Whatcheeria deltae, document evidence fibrolamellar bone-primary tissue associated growth. Our data indicate that juveniles grew rapidly reached skeletal maturity quickly, allowing them occupy large-bodied predator niche in their paleoenvironment. This strategy contrasts those other indicates diversity patterns existed at origins diversification. Importantly, marks unexpectedly early occurrence Tetrapoda, both temporally phylogenetically. These findings reveal elevated juvenile is not limited amniotes, but deep clade may have played previously unrecognized role invasion land.

Language: Английский

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Inferring longevity from advanced rib remodelling in insular dwarf deer

Biological Journal of the Linnean Society, Journal Year: 2022, Volume and Issue: 136(1), P. 41 - 58

Published: Feb. 15, 2022

Abstract Dwarfed insular mammals are of significant interest to evolutionary biology because their morphological and physiological adaptations triggered by variables inherent geographical isolation. One life history trait that is expected be modified in relation body size reduction extended longevity facilitated ecological parameters such as predator competitor release fluctuating resource availability. However, systematic examination extreme cases dwarfism difficult largely represented fossils extinct species. We studied seven rib fragments the extraordinary endemic Pleistocene dwarf deer Candiacervus (size 2) test whether its bone matrix shows evidence for extensive remodelling typically seen large long-living mammals. found all ribs had well-remodelled Haversian bone, implying several generations resorption re-deposition processes. Osteon density was high relative small cross-section size, with examples porosity similar elderly animals. report first combined micro-morphological micro-morphometric record histology, agreeing previous literature discussing ruminants. Further experimental validation osteon extant will confirm dwarfed indeed lived longer than mass.

Language: Английский

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Interelemental osteohistological variation in Massospondylus carinatus and its implications for locomotion

PeerJ, Journal Year: 2022, Volume and Issue: 10, P. e13918 - e13918

Published: Sept. 23, 2022

Massospondylus carinatus Owen, 1854 is an iconic basal sauropodomorph dinosaur from the Early Jurassic of southern Africa. Over 200 specimens have been referred to this taxon, spanning entire ontogenetic series embryo adult. Consequently, it provides ideal sample for investigating developmental biology, including growth patterns and rates, through osteohistological analysis. was first early-branching which a femoral sampled. Since then, other non-avian taxa shown that plasticity, interelemental variation, locomotory shifts can complicate our understanding curves patterns. To investigate these questions further, necessary multiple skeletal elements individuals across large range sizes, something often hindered by incompleteness fossil record. Here, we conducted broad, multielement study long bones (excluding metapodials) 27 span its series. Our reveals substantial variations in history. A cyclical woven-parallel complex predominant bone tissue pattern during early mid-ontogeny, transitions slower forming parallel-fibred very late ontogeny. The interrupted irregularly spaced marks (CGMs) lines arrested indicating temporary cessations growth. These CGMs show previously recorded plasticity also visible bones, with poor correlation between body size (measured midshaft circumference) CGM numbers. Furthermore, found trajectory individual vary depending on limb element studied. This makes establishment accurate curve determination onset reproductive maturity difficult taxon. Finally, no evidence differential rates forelimb vs hindlimb samples same individual, providing further falsifying hypothesised postural carinatus.

Language: Английский

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Vertebrae reveal industrial-era increases in Atlantic bluefin tuna catch-at-size and juvenile growth

ICES Journal of Marine Science, Journal Year: 2023, Volume and Issue: 80(4), P. 836 - 847

Published: Feb. 11, 2023

Abstract Climate change and size-selective overexploitation can alter fish size growth, yet our understanding of how to what extent is limited due a lack long-term biological data from wild populations. This precludes ability effectively forecast population dynamics support sustainable fisheries management. Using modern, archived, archaeological vertebrae dimensions growth rings one the most intensely exploited populations, eastern Atlantic Mediterranean bluefin tuna (Thunnus thynnus, BFT), we estimated catch-at-size early-life patterns 3rd century bce 21st ce understand responses changes in its environment. We provide novel evidence that BFT juvenile increased between 16th–18th, 20th, centuries, correlated with warming climate likely decrease stock biomass. found it equally plausible fisheries-induced evolution has acted increase driving earlier maturation as result exploitation. Coincidently, suggest long history large ( >200 cm FL) capture. Instead, was relatively small comparison more intensive, 20th trap which operated further shore. complex issue would benefit studies using fine-scale biochronological analyses otoliths adaptation genomics, throughout last especially, determine evolutionary exploitation, disentangle influence temperature biomass on growth.

Language: Английский

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