Cranial osteology and neuroanatomy of the late Permian reptile Milleropsis pricei and implications for early reptile evolution

Royal Society Open Science, Год журнала: 2025, Номер 12(1)

Опубликована: Янв. 1, 2025

Millerettidae are a group of superficially lizard-like Permian stem reptiles originally hypothesized as relevant to the ancestry reptile crown group, and particularly lepidosaurs archosaurs. Since advent cladistics, millerettids have typically been considered be more distant relatives earliest-diverging parareptiles therefore outside ‘Eureptilia’. Despite this cladistic consensus, some conspicuous features millerettid anatomy invite reconsideration their relationships. We provide detailed description late Milleropsis pricei using synchrotron X-ray phase-contrast micro-computed tomography focusing on cranial three individuals known from burrow aggregation. Our data reveal suite neuroanatomical shares with neodiapsids that absent both in other ‘parareptiles’ early diverging groups ‘eureptiles’. Traits shared between include: presence tympanic emargination quadrate, quadratojugal squamosal, loss epipterygoid contribution basicranial articulation suggesting kinetic palatoquadrate, absence sphenethmoid pathway abducens nerve through braincase. findings suggest neurocranium, region poorly sampled phylogenetic analyses due relative visual inaccessibility poor preservation, has potential inform relationships reptiles.

Язык: Английский

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New information on the anatomically derived millerettid Milleretta rubidgei from the latest Permian based on µCT data

Zoological Journal of the Linnean Society, Год журнала: 2025, Номер 203(3)

Опубликована: Март 1, 2025

Abstract The fossil reptile Milleretta holds a prominent role in phylogenetic analyses of early relationships. It has often been used as the sole marker for anatomically diverse middle to late Permian Millerettidae, clade that hypothesized earliest diverging parareptiles and therefore only distantly related crown group. However, anatomy remains incompletely documented, presenting an obstacle studies evolution. We re-examine cranial rubidgei using synchrotron micro-computed tomography two specimens, representing juvenile subadult. These immature individuals have clearly visible sutures, differing from osteologically mature individuals, which osteoderms obscure anatomy, particularly antorbital region. demonstrate other millerettids share many derived similarities with Neodiapsida (a includes group), neurocranium palatoquadrate. Comparison reveals some features seen adult specimens are, fact, features, resulting secondary modification individuals. observations suggest is millerettid urge caution this taxon semaphorant disparate group stem reptiles.

Язык: Английский

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Neurosensory anatomy of Varanopidae and its implications for early synapsid evolution

Journal of Anatomy, Год журнала: 2021, Номер 240(5), С. 833 - 849

Опубликована: Ноя. 14, 2021

Abstract Varanopids are a group of Palaeozoic terrestrial amniotes which represent one the earliest‐diverging groups synapsids, but their palaeoneurology has gone largely unstudied and recent analyses have challenged traditional placement within synapsids. We utilized computed tomography (CT) to study virtual cranial otic endocasts six varanopids, including representative taxa both mycterosaurines varanodontines. Our results show that varanopid brain is plesiomorphic, being tubular in shape showing no expansion cerebrum or olfactory bulbs, distinct highly expanded floccular fossae. The housing bony labyrinth also distinct, bounded almost entirely by supraoccipital‐opisthotic complex, with prootic only bordering ventral portion vestibule. surprisingly well‐ossified, clearly preserving elliptical, sub‐orthogonal canals, prominent ampullae, short, undifferentiated vestibule; this high degree ossification similar seen therapsid synapsids supports varanopids Synapsida. enlarged anterior canal, together orthogonal canals fossa, lend support for fast head movements indicated inferred predatory feeding mode varanopids. Reconstructed neurosensory anatomy indicates may much lower‐frequency hearing range compared more derived suggesting that, despite gaining some active features, retain plesiomorphic capabilities. As whole, our data reveal neuroanatomy pelycosaur‐grade far complex than previously anticipated.

Язык: Английский

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Early Origins of Divergent Patterns of Morphological Evolution on the Mammal and Reptile Stem-Lineages

Systematic Biology, Год журнала: 2022, Номер 71(5), С. 1195 - 1209

Опубликована: Март 10, 2022

The origin of amniotes 320 million years ago signaled independence from water in vertebrates and was closely followed by divergences within the mammal reptile stem lineages (Synapsida Reptilia). Early members both groups had highly similar morphologies, being superficially "lizard-like" forms with many plesiomorphies. However, extent to which they might have exhibited divergent patterns evolutionary change, potential explain large biological differences between their living members, is unresolved. We use a new, comprehensive phylogenetic dataset quantify variation rates constraints morphological evolution among Carboniferous-early Permian amniotes. find evidence for an early burst rates, resulting origins morphologically distinctive subgroups that mostly persisted through Cisuralian. Rates declined substantially time, especially reptiles. also more constrained compared synapsids, exploring limited character state space. Postcranial innovation particular important potentially related body size. In contrast, reptiles predominantly varied temporal region, suggesting disparity skull jaw kinematics, foreshadowing variability cranial biomechanics seen today. Our results demonstrate synapsids underwent divergence macroevolutionary patterns. This laid foundation subsequent events may be critical understanding substantial mammals Potential explanations include developmental processes or ecological factors, warranting cross-disciplinary investigation. [Amniote; size; constraint; phylogeny; rate.].

Язык: Английский

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A comprehensive phylogeny and revised taxonomy of Diadectomorpha with a discussion on the origin of tetrapod herbivory

Royal Society Open Science, Год журнала: 2024, Номер 11(6)

Опубликована: Июнь 1, 2024

Among terrestrial tetrapods, the origin of herbivory marked a key evolutionary event that allowed for evolution modern ecosystems. A 100 Ma gap separates oldest tetrapods and first undisputed herbivorous tetrapods. While four clades early tetrapod herbivores are amniotes, phylogenetic position Diadectomorpha with respect to Amniota has long been controversial. Given coincides obligate is unknown within amphibians, this suggests adaptation necessary evolve unique amniotes. Historically, analyses have found as sister-group but recent recover Synapsida, Amniota. We tested whether diadectomorphs amniotes by updating most character–taxon matrix. Specifically, we added new characters from lower jaw diadectomorph taxa, resulting in dataset 341 61 operational taxonomic units. updated description five jaws using microcomputed tomography data. Our majority-rule consensus places Synapsida; other methods do not relationship. revise taxonomy, erecting species Permian Bromacker locality, Germany, genus accommodate ‘ Diadectes’ sanmiguelensis .

Язык: Английский

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The recumbirostran Hapsidopareion lepton from the early Permian (Cisuralian: Artinskian) of Oklahoma reassessed using HRμCT, and the placement of Recumbirostra on the amniote stem

Papers in Palaeontology, Год журнала: 2025, Номер 11(1)

Опубликована: Янв. 1, 2025

Abstract Recumbirostra is a clade of heavily modified, superficially lizard‐like tetrapods that were originally interpreted as ‘microsaurian lepospondyls’ unrelated to the amniote crown. However, recent work has placed within Reptilia, based on many similarities between braincase and postcranium recumbirostrans with early reptiles. Here, Permian hapsidopareiid recumbirostran Hapsidopareion lepton re‐described using high‐resolution μCT data three individuals across distinct ontogenetic stages, including holotype specimen. These reveal suite Llistrofus pricei , suggesting latter subjective junior synonym . Furthermore, we highlight derived features present in Amniota are otherwise absent reptiliomorphs, including: single supraoccipital element contributes endosseous labyrinths, absence paired endolymphatic fossae, presence ampullary fossa semicircular canals. We also identify plesiomorphies skull roof stem‐amniotes but lacking unambiguous crown amniotes. This suggests previously uniting reptiles possible symplesiomorphies Amniota, new phylogenetic analysis places crownward group along stem, more than traditionally recognized reptiliomorphs such Seymouria Our findings need for further anatomical descriptive studies both stem‐ crown‐group amniotes, specifically revisions those taxa regarded ‘microsaurs’.

Язык: Английский

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Predatory synapsid ecomorphology signals growing dynamism of late Palaeozoic terrestrial ecosystems

Communications Biology, Год журнала: 2024, Номер 7(1)

Опубликована: Фев. 17, 2024

Terrestrial ecosystems evolved substantially through the Palaeozoic, especially Permian, gaining much new complexity, among predators. Key these predators were non-mammalian synapsids. Predator ecomorphology reflect interactions with prey and competitors, which are key controls on carnivore diversity ecology. Therefore, carnivorous synapsids may offer insight wider ecological evolution as first complex, tetrapod-dominated, terrestrial formed late Palaeozoic. Using morphometric phylogenetic comparative methods, we chart synapsid trophic morphology from latest Carboniferous to earliest Triassic (307-251.2 Ma). We find a major morphofunctional shift in carnivory between early middle via addition of feeding modes increasingly specialised for greater biting power or speed that captures growing antagonism dynamism tetrapod predator-prey interactions. The further hypo- hypercarnivorous highlight nascent intrinsic pressures complexification across mid-late Permian.

Язык: Английский

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Endocasts of the basal sauropsid Captorhinus reveal unexpected neurological diversity in early reptiles

The Anatomical Record, Год журнала: 2022, Номер 306(3), С. 552 - 563

Опубликована: Окт. 14, 2022

Abstract Captorhinids are a group of Paleozoic amniotes that represents one the earliest‐diverging clades eureptiles. Although captorhinids best‐known and most well‐studied early amniotes, their palaeoneuroanatomy has gone largely unexamined. We utilized neutron computed tomography to study virtual cranial otic endocasts two captorhinid specimens. The neurosensory anatomy shows mixture traits considered plesiomorphic for sauropsids (no expansions cerebrum or olfactory bulbs, low degree encephalization, ossification capsule) those more derived, including moderate cephalic pontine flexures dorsoventrally tall bony labyrinth. inner ear clearly preserves elliptical, sub‐orthogonal canals short, rounded vestibule, along with an unusually enlarged lateral canal unique curvature posterior canal. reconstructed indicates were sensitive slightly higher frequencies than many contemporaries, likely reflecting differences in body size across taxa, while morphology maxillary suggests simple, tubular condition as state Sauropsida contributes ongoing discussions regarding phylogenetic placement varanopids. This first detailed tomographic brain any basal eureptile. new data described here reveal neuroanatomy is far complex diverse previously anticipated, provide impetus further exploration amniotes.

Язык: Английский

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Skeletal anatomy of the early Permian parareptile Delorhynchus with new information provided by neutron tomography

PeerJ, Год журнала: 2023, Номер 11, С. e15935 - e15935

Опубликована: Авг. 22, 2023

Detailed description of the holotype skeleton Delorhynchus cifellii , made possible through use neutron tomography, has yielded important new information about cranial and postcranial anatomy this early Permian acleistorhinid parareptile. Hitherto unknown features skull include a sphenethmoid, paired epipterygoids complete neurocranium. In addition, stapes been exposed in three dimensions for first time an Postcranial material found articulation with allows detailed vertebrae, ribs, shoulder girdle humerus parareptile, allowing reevaluation phylogenetic relationships taxon other acleistorhinids, more broadly among parareptiles. Results show that is recovered as sister Colobomycter ‘acleistorhinids’ now Lanthanosuchus .

Язык: Английский

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At the root of the mammalian mind: The sensory organs, brain and behavior of pre-mammalian synapsids

Progress in brain research, Год журнала: 2022, Номер unknown, С. 25 - 72

Опубликована: Ноя. 18, 2022

Язык: Английский

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