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

Royal Society Open Science, Journal Year: 2025, Volume and Issue: 12(1)

Published: Jan. 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.

Language: Английский

---

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

Zoological Journal of the Linnean Society, Journal Year: 2025, Volume and Issue: 203(3)

Published: March 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.

Language: Английский

---

‘Birds’ of two feathers: Avicranium renestoi and the paraphyly of bird-headed reptiles (Diapsida: ‘Avicephala’)

Zoological Journal of the Linnean Society, Journal Year: 2024, Volume and Issue: unknown

Published: May 11, 2024

Abstract The anatomy of Late Triassic drepanosauromorphs is re-examined, with a focus on the previously published surface models holotype Avicranium renestoi from Norian North America. We comment cranial this taxon and propose new reconstruction skull mandible. Contrary to previous interpretations, entire rostrum most palate are not preserved in specimen. also suggest that some proposed plesiomorphic characters may result incomplete ossification due immaturity. These observations compiled into morphological phylogenetic dataset designed address monophyly ‘Avicephala’, group comprising Permian gliding reptiles Weigeltisauridae, chameleon-like Drepanosauromorpha. recover Weigeltisauridae as stem-saurian diapsids Drepanosauromorpha sister-group Trilophosauridae among archosauromorphs, thus implying paraphyly ‘Avicephala’. Drepanosauromorphs trilophosaurids recovered sister-taxa for first time, supported by several postcranial synapomorphies. This position reduces group’s ghost lineage now does necessarily cross Permian–Triassic boundary. However, much remains unknown early history drepanosauromorphs, evolution arboreality archosauromorph reptiles.

Language: Английский

---

A new stem saurian reptile from the late Permian of South Africa and insights into saurian evolution

Swiss Journal of Palaeontology, Journal Year: 2025, Volume and Issue: 144(1)

Published: Feb. 26, 2025

Abstract The evolutionary radiation of diapsid reptiles that includes all extant and most extinct is well-represented in the Mesozoic Cenozoic fossil records, however, earliest stages recorded Paleozoic Era are limited to comparatively few taxa. Consequently, origins Sauria, crown-group Diapsida, remains poorly understood phylogenetic positions known taxa along saurian stem controversial. Here, we describe Akkedops bremneri sp. et gen. nov., a new early late Permian from Karoo South Africa based on two skulls show famous aggregation "juvenile Youngina ” SAM-PK-K7710 also referrable it, thereby making this one best-known saurians. skull has short rostrum, open lower temporal bar, large contribution postfrontal upper fenestra, slender stapes, sliver-like supratemporal with distinct lateral flange suturing postorbital, lacks both postparietal tabular bones. saddle-shaped quadrate rather saurian-like being posteriorly emarginated tympanic crest unique medial flange. post cranial skeleton lizard-like notably shows hook-shaped fifth metatarsal thyroid fenestra. Phylogenetic analysis recovers as sister which especially surprising considering its small size slender, morphology prior split between apparently similar lepidosauromorphs many robust archosauromorph Our indicates capensis falls outside clade bremenri + Sauria does not appear form other “younginiform” reptiles. available evidence level complexity related evolution saurians origin occurred shadow amniotes.

Language: Английский

---

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, Journal Year: 2025, Volume and Issue: 11(1)

Published: Jan. 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’.

Language: Английский

---

The neodiapsid Thadeosaurus colcanapi from the upper Permian of Madagascar

Papers in Palaeontology, Journal Year: 2025, Volume and Issue: 11(2)

Published: March 1, 2025

Abstract The enigmatic neodiapsid Thadeosaurus colcanapi (Lower Sakamena Formation, southwestern Madagascar), sole species of the genus , is revised here. attribution 12 21 referred specimens confirmed, spanning all ontogenetic stages, and anatomy redescribed in detail with comments on ontogenetical differences. This new anatomical information included an expanded phylogenetical dataset tailored to examine relationships Permo‐Triassic diapsids. A stem‐saurian position confirmed here for ‘younginiforms’, which are recovered paraphyletic, Youngina representing earlier‐diverging taxon. However, this topology extremely labile, monophyly or paraphyly ‘younginiforms’ could not be unequivocally supported. In contrast, our analyses provide good support a monophyletic Tangasauridae including other ‘younginiforms’. as member sister‐group putative semi‐aquatic Tangasaurinae moderate degree support, despite large amounts missing data lesser‐known tangasaurids partially obscuring understanding tangasaurid interrelationships. Last, considered have inhabited nearshore, probably riparian, environment, although it remains unclear whether was fully terrestrial. Further examinations tangasaurids, well novel morphotype identified Lower Formation Madagascar, evidence deepen evolution palaeoecology Tangasauridae.

Language: Английский

---

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

---

The origin of Amniota in phylogenetic context

Published: Feb. 5, 2024

The membership, phylogeny and external relationships of Amniota quickly achieved “textbook wisdom” status in the mid-1990s, but were all called into question by phylogenetic analyses last few years. However, these their predecessors have either focused on early limbed vertebrates barely extended Amniota, or amniotes included very non-amniotes as outgroups. Here I take an analysis first type, perform corrections updates, enlarge its sample amniote-related characters (among other things) order to test matters. Despite high rates homoplasy, my matrix supports “microsaurs” amphibians, perhaps even less close than Seymouriamorpha. For Diadectomorpha “classical” position stem Pan-Amniota is weakly supported; this has, however, greatly expanded include many supposed amniotes, among others fish-scaled Brouffia. recent finding Petrolacosaurus outside Diapsida, indeed along with Captorhinidae, is—weakly—corroborated despite quite different taxon character samples. Caseasauria, normally considered part Pan-Mammalia, instead nested “parareptiles” within Sauropsida; Varanopidae, similarly traditionally placed pan-mammals, emerges three separate sauropsid positions. A period small body size around origin amniotic egg not supported optimal trees, trees that seem compatible it are nearly optimal. Slightly worse allow for aïstopods limbless anthracosaurs. generally low support highlights specific needs future research. Still, appears recently proposed membership traditional can be excluded reasonable confidence, a Anthracosauria crownward Temnospondyli temnospondyl any extant amphibians. Coding temporal bone taxa tabular supratemporal has practically no effect.

Language: Английский

---

A new species of Palacrodon and a unique form of tooth attachment in reptilesCitation for this article: Jenkins, K. M., Bell, C. J., Hancox, P. J., & Lewis, P. J. (2024) A new species of Palacrodon and a unique form of tooth attachment in reptiles. Journal of Vertebrate Paleontology . https://doi.org/10.1080/02724634.2024.2328658

Journal of Vertebrate Paleontology, Journal Year: 2023, Volume and Issue: 43(5)

Published: Sept. 3, 2023

Palacrodon, a near-crown stem reptile, is known from several Triassic sites across the globe, and easily recognized by its dentition characterized labiolingually expanded molariform teeth coupled with acrodont tooth implantation. Here we explore nature of implantation attachment in specimens Palacrodon South Africa Arizona, U.S.A. using µCT. We note presence unusual ridges located underneath crowns browni. Such are not present which warrants naming new species P. parkeri. conducted broad survey internal morphology extant extinct pan-reptiles (n = 212), conclude that homologous like those observe browni any other reptile. As such, our ability to determine function limited, though hypothesize it related via unmineralized soft tissues.

Language: Английский

---

A small venomous reptile from the Late Triassic (Norian) of the southwestern United States

PeerJ, Journal Year: 2024, Volume and Issue: 12, P. e18279 - e18279

Published: Oct. 14, 2024

Reptile feeding strategies encompass a wide variety of diets and accompanying diversity in methods for subduing prey. One such strategy, the use venom prey capture, is found living reptile clades like helodermatid (beaded) lizards some groups snakes, secreting glands are also present monitor iguanians. The fossil record these shows strong evidence use, this strategy has been hypothesized extinct reptiles ( e.g ., archosauromorphs, anguimorphs, sphenodontian). However, systems delivery its evolutionary origins scarce, especially when based on more than isolated teeth. Here, we describe potentially venomous new reptile, Microzemiotes sonselaensis gen. et sp. nov., from partial left dentary recovered Sonsela Member Chinle Formation (middle Norian, Upper Triassic) northeastern Arizona, U.S.A. three teeth have apices that distally reclined relative to their bases tip posteriormost tooth curves mesially. show subthecodont implantation interspaced by empty sockets terminate above Meckelian canal, which dorsoventrally expanded posteriorly. Replacement positioned distolingually active as varanid-like replacement. We identify specimen diapsid monocuspid lack carinae serrations. A exclusive phylogenetic position within Diapsida not well supported remains uncertain. Several features taxon, presence an intramandibular septum, shared with anguimorph squamates; however, likely evolved independently. taxon distinctively marked external grooves occur entire length crown labial lingual sides, seen beaded lizards. If functionally similar those lizards, deliver venom, represents oldest known where venom-conducting preserved jaw. species anatomically distinct ~10x smaller only other Late Triassic Uatchitodon , supporting across multiple different body size classes. This third possibly used envenomation (and/or defensive) adding small number Mesozoic Era.

Language: Английский

---