Cranial ecomorphology of turtles and neck retraction as a possible trigger of ecological diversification

Evolution, Journal Year: 2022, Volume and Issue: 76(11), P. 2566 - 2586

Published: Sept. 19, 2022

Turtles have a highly modified body plan, including rigid shell that constrains postcranial anatomy. Skull morphology and neck mobility may therefore be key to ecological specialization in turtles. However, the signal of turtle skull morphologies has not been rigorously evaluated, leaving uncertainties about roles adaptation convergence. We evaluate cranial ecomorphology using three-dimensional geometric morphometrics phylogenetic comparative methods. shape correlates with allometry, retraction capability, different aquatic feeding ecologies. find variables influence only, whereas functional variable (the capacity for retraction) influences both size. Ecology predictions from are validated by high success rates extant species, outperforming previous two-dimensional approaches. use this infer traits extinct species. Neck evolved among crownward stem-turtles Late Jurassic, signaling decoupling shell, possibly linked major episode ecomorphological diversification. also strong evidence convergent adaptations marine groups. This includes parallel loss retraction, active hunting, possible grazing, suction Our large-scale assessment dietary throughout evolution reveals timing origin their distinct ecomorphologies, highlights potential ecology function effects on form.

Language: Английский

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A systematic comparative description of extant turtle humeri, with comments on humerus disparity and evolution based on fossil comparisons

The Anatomical Record, Journal Year: 2024, Volume and Issue: 307(11), P. 3437 - 3505

Published: May 8, 2024

The humerus is central for locomotion in turtles as quadrupedal animals. Osteological variation across testudine clades remains poorly documented. Here, we systematically describe the anatomy all major extant turtle based on 38 species representing phylogenetic and ecological diversity of crown turtles. Three Late Triassic shelled stem (Testudindata) are included to establish plesiomorphic morphology. Our work 3D models, establishing a publicly available digital database. Previously defined terms anatomical sides (e.g., dorsal, ventral) often not aligned with respective body other animals sprawling gait. We propose alternative directional simplify communication: radial ulnar (the articulating radius/ulna), capitular side bearing humeral head), intertubercular (opposite surface). Turtle humeri show low morphological exceptions concentrated locomotory specialists. 15 discrete characters summarize osteological future studies. Disparity analyses comparing non-shelled indicate that presence shell constrains variation. Flippered aquatic released from this constraint significantly increase overall disparity. Ontogenetic changes related increased ossification pronunciation proximal processes, distal articulation areas, closure ectepicondylar groove foramen. Some retain juvenile features into adulthood provide evidence paedomorphic evolution. review morphology throughout evolution its group.

Language: Английский

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Skin, scales, and cells in a Jurassic plesiosaur

Current Biology, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 1, 2025

Highlights•The first in-depth study of plesiosaur soft tissues is reported•Some plesiosaurs had smooth skin on the body and small scales flippers•Scales likely enhanced swimming and/or grip substrate during feedingSummaryPlesiosaurs are an iconic group Mesozoic marine reptiles with evolutionary history spanning over 140 million years (Ma).1 Their skeletal remains have been discovered worldwide; however, accompanying fossilized exceptionally rare.2 Here, we report a virtually complete from Lower Jurassic (∼183 Ma)3 Posidonia Shale Germany that preserves traces around tail front flipper. The integument was apparently scale-less retains identifiable melanosomes, keratinocytes cell nuclei, stratum corneum, spinosum, basale epidermis. Molecular analysis reveals aromatic aliphatic hydrocarbons denote degraded original organics. flipper otherwise integrates small, sub-triangular structures reminiscent modern reptilian scales. These may influenced hydrodynamics provided traction benthic feeding. Similar to other sea-going reptiles,4,5,6,7,8,9,10 scalation covering at least part therefore probably augmented paleoecology plesiosaurs.

Language: Английский

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Simple shell measurements do not consistently predict habitat in turtles: a reply to Lichtig and Lucas (2017)

Peer Community Journal, Journal Year: 2025, Volume and Issue: 5

Published: Jan. 2, 2025

Inferring palaeoecology for fossils is a key interest of palaeobiology. For groups with extant representatives, correlations aspects body shape ecology can provide important insights to understanding extinct members lineages. The origin and ancestral turtles debated various shell or limb proportions have been reported correlate habitat among turtles, such that they may be informative inferring the fossil including early shelled stem turtles. One recently described method proposes simple measurements effectively quantify doming plastron width differentiate classes in linear discriminant analysis, whereby aquatic low domed shells narrow plastra. respective study unorthodox predictions lifestyles turtle Proganochelys quenstedtii meiolaniform Meiolania platyceps, terrestrial habits Proterochersis robusta. Here, we show these published results are consequence questionable methodological choices as omission species data which do not conform preconceived shape-ecology association. When reversed, corrected, phylogenetic flexible analysis applied, cannot correctly predicted based on measurements. This invalidates well proposed palaeohabitats fossils.

Language: Английский

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The ecological diversification and evolution of Teleosauroidea (Crocodylomorpha, Thalattosuchia), with insights into their mandibular biomechanics

Ecology and Evolution, Journal Year: 2022, Volume and Issue: 12(11)

Published: Nov. 1, 2022

Abstract Throughout the Jurassic, a plethora of marine reptiles dominated ocean waters, including ichthyosaurs, plesiosaurs and thalattosuchian crocodylomorphs. These Jurassic ecosystems were characterized by high niche partitioning spatial variation in dietary ecology. However, while ecological diversity many reptile lineages is well known, overall diversification Teleosauroidea (one two major groups within crocodylomorphs) has never been explored. Teleosauroids previously deemed to have morphologically conservative body plan; however, they actuality morphofunctionally more diverse than thought. Here we investigate ecology feeding specializations teleosauroids, using morphological functional cranio‐dental characteristics. We assembled most comprehensive dataset date teleosauroid taxa (approximately 20 species) ran series principal component analyses (PC) categorize them into various ecomorphotypes based on 17 dental characteristics (38 specimens) 16 functionally significant mandibular characters (18 specimens). The results examined conjunction with phylogeny (153 502 characters) evaluate macroevolutionary patterns shifts. Machimosaurids display well‐developed shift from: (1) slender, pointed tooth apices an elongate gracile mandible; (2) robust, teeth slightly deeper finally, (3) rounded deep‐set, shortened mandible enlarged musculature. Overall, there limited variability teleosaurids machimosaurids, despite differing cranial morphologies habitat preferences certain taxa. This suggests narrow divide between machimosaurids. Resource was primarily related snout skull length as habitat; only twice did teleosauroids manage make evolutionary leap feed distinctly differently, derived machimosaurines successfully radiating new ecologies.

Language: Английский

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Virtual reconstruction of a Late Jurassic metriorhynchid skull from Switzerland and its use for scientific illustration and paleoart

MorphoMuseuM, Journal Year: 2023, Volume and Issue: 9(3), P. e178 - e178

Published: May 22, 2023

The democratization of 3D techniques in recent years provides exciting new opportunities for the study complex fossils.In present contribution, we provide a virtual reconstruction partial, disarticulated metriorhynchid (Metriorhynchidae, Thalattosuchia, Crocodylomorpha) skull from Late Jurassic northwestern Switzerland.This was used to produce high quality scientific illustrations whole descriptive purposes.The reconstructed also served estimation total body length specimen and propose life animal its paleoenvironment.In an effort transparency, review sources that were consulted explain choices had make.

Language: Английский

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New insights into the early morphological evolution of sea turtles by re-investigation of Nichollsemys baieri, a three-dimensionally preserved fossil stem chelonioid from the Campanian of Alberta, Canada

Swiss Journal of Palaeontology, Journal Year: 2024, Volume and Issue: 143(1)

Published: July 12, 2024

Abstract The early evolution of Pan-Chelonioidea (sea turtles) is poorly understood. This in part due to the rarity undeformed skulls definitive stem chelonioids. In this work, we redescribe holotype Nichollsemys baieri using µCT scans and segmentations skull. fossil best 3D preserved skull any Campanian sea turtle, includes partial “soft tissue” preservation. morphologically similar but clearly distinct from Toxochelys spp., both show a mosaic plesiomorphic derived chelonioid features. internal cranial anatomy documents presence characters that are absent such as loss epipterygoids rod-like shape rostrum basisphenoidale. Among numerous splenial bone, which was unnoticed before. An updated phylogenetic analysis retrieves non-protostegid slightly more crownward position than latiremis . Our phylogeny macrobaenids protostegids pan-chelonioids, find unorthodox results for dermochelyids. Thus, although provides important new insights into morphological turtles, much work remains be done. As completely specimen, included recent landmark-based dataset turtles. Morphospace reveals an intermediate between cryptodires crown Based on these data, also predict still capable neck retraction, constraining trait pan-chelonioids.

Language: Английский

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The onset of large size in Cretaceous marine turtles (Protostegidae) evidenced by new fossil remains from the Valanginian of Colombia

Zoological Journal of the Linnean Society, Journal Year: 2023, Volume and Issue: 202(1)

Published: July 12, 2023

Abstract The evolution of large size in vertebrates is a fascinating research topic, relevant, for example, the Cretaceous turtles Protostegidae clade, which includes some largest to have ever inhabited Earth. However, there still limited understanding regarding when and under what conditions emerged this group. Here we describe several limb bones fossil shell remains from upper Valanginian, Rosa Blanca Formation Colombia that, together, shed light on onset characteristics large-size protostegids. material, although fragmentary, preserves enough features, such as sigmoidal curvature shaft humeri anterior view their strong waist, be attributed Protostegidae. described here constitute known Early worldwide oldest record ecological climatic northern South America during Late Valanginian are discussed potential triggers emergence body protostegid turtles.

Language: Английский

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The topological organization of the turtle cranium is constrained and conserved over long evolutionary timescales

The Anatomical Record, Journal Year: 2023, Volume and Issue: 307(8), P. 2713 - 2748

Published: Dec. 16, 2023

Abstract The cranium of turtles (Testudines) is characterized by the secondary reduction temporal fenestrae and loss cranial joints (i.e., characteristics anapsid, akinetic skulls). Evolution ontogeny turtle are associated with shape changes. Cranial variation among Testudines can partially be explained dietary functional adaptations (neck retraction), but it unclear if topology shows similar ecomorphological signal, or decoupled from evolution. We assess topological arrangement bones number, relative positioning, connections), using anatomical network analysis. Non‐shelled stem have arrangements to archosauromorph outgroups. Shelled (Testudinata) evolve a unique organization that bone losses (e.g., supratemporal, lacrimal, ectopterygoid) an increase in complexity densely highly interconnected skulls low path lengths between bones), resulting closure skull openings establishment unusual connections such as parietal–pterygoid contact braincase. Topological changes evolutionarily predate many taxonomic morphospace discrimination crown low, indicating may constrained. Observed results repeated nonintegral premaxilla, nasal, epipterygoid, quadratojugal), emarginations palate construction. observe only minor ontogenetic Topology not influenced diet habitat, contrasting shape. Our indicate reptiles conserved after its initial establishment, different evolutionary histories.

Language: Английский

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Limb anatomy of the Triassic turtles: appendicular osteology of Proterochersis (Testudinata, Proterochersidae)

Zoological Journal of the Linnean Society, Journal Year: 2023, Volume and Issue: 199(3), P. 771 - 831

Published: July 25, 2023

Abstract The turtle locomotor system is heavily modified owing to the severe impact of development shell on body plan these reptiles. Although limb and girdle osteology earliest, Triassic turtles relatively well understood in general, exact impacts variability, ontogeny preservation (e.g. deformation) observed morphologies have rarely been considered detail. Here, we describe detail document intraspecific variability limbs girdles Proterochersis spp., basalmost true (Testudinata). We also provide a synthesis currently available data detailed comparisons with other stem gain better understanding diagnostic value early appendicular skeleton pave way for future biomechanical functional studies. Our suggest that spp. could be at least partly aquatic change their preferred habitat during ontogeny, larger (and, presumably, older) specimens presenting more characters suggestive terrestrial environment.

Language: Английский

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