A new early‐diverging probainognathian cynodont and a revision of the occurrence of cf. Aleodon from the Chañares Formation, northwestern Argentina: New clues on the faunistic composition of the latest Middle–?earliest Late Triassic Tarjadia Assemblage Zone

The Anatomical Record, Journal Year: 2024, Volume and Issue: 307(4), P. 818 - 850

Published: Jan. 29, 2024

Abstract The Chañares Formation (Ischigualasto‐Villa Unión Basin) is worldwide known by its exquisitely preserved fossil record of latest Middle‐to‐early Late Triassic tetrapods, including erpetosuchids, “rauisuchians,” proterochampsids, gracilisuchids, dinosauromorphs, pterosauromorphs, kannemeyeriiform dicynodonts, and traversodontid, chiniquodontid probainognathid cynodonts, coming from the Tarjadia (bottom) Massetognathus ‐ Chanaresuchus (top) Assemblage Zones lower member. Regarding most profuse knowledge comes traditional layers discovered Alfred Romer his team in 1960s that are now enclosed Zone (AZ). In this contribution we focus our study on probainognathian cynodonts levels Zone. We describe a new cynodont with transversely broad postcanine teeth ( Riojanodon nenoi gen. et sp. nov.) which related to genus Aleodon . addition, specimen CRILAR‐Pv 567 previously referred cf. here described, compared, included phylogenetic analysis. It considered as an indeterminate Aleodontinae nov., clade proposed chiniquodontids upper postcanines, having cuspidated sectorial labial margin lingual platform twice broader than cingulum. Cromptodon mamiferoides , Cerro de Las Cabras (Cuyo Basin), was also analysis recovered Aleodontinae. indet. reinforce faunal differentiation between Zones, member Formation, inform diverse both teeth.

Language: Английский

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The origin and evolution of Cynodontia (Synapsida, Therapsida): Reassessment of the phylogeny and systematics of the earliest members of this clade using 3D‐imaging technologies

The Anatomical Record, Journal Year: 2024, Volume and Issue: 307(4), P. 1634 - 1730

Published: March 5, 2024

Abstract The origin of cynodonts, the group ancestral to and including mammals, is one major outstanding problems in therapsid evolution. One most troubling aspects cynodont fossil record lengthy Permian ghost lineage between latest possible divergence from its sister Therocephalia first appearance definitive cynodonts late Permian. absence dominance therocephalians middle strata has led some workers argue that evolved within therocephalians, rendering latter paraphyletic, but more recent analyses support reciprocal monophyly Cynodontia Therocephalia. Furthermore, although a fundamental dichotomy derived subclade Eucynodontia well‐supported phylogeny, relationships stemward Early Triassic are unresolved. Here, we provide re‐evaluation phylogeny Eutheriodontia (Cynodontia + Therocephalia) an assessment character evolution group. Using computed tomographic data extensive sampling earliest known (late Triassic) selected exemplars later (Middle onwards) describe novel endocranial anatomy these animals. These were incorporated into new phylogenetic set comprehensive sample early cynodonts. Our results previously recovered by other authors, recover as paraphyletic with regards eutherocephalians forming clade exclusion “basal therocephalian” families Lycosuchidae Scylacosauridae. Though both conservatism homoplasy mark non‐mammalian able identify several synapomorphies for eutheriodont subclades generally better‐supported topologies than previous using primarily external craniodental characters.

Language: Английский

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New insights into the postcranial anatomy of Exaeretodon riograndensis (Eucynodontia: Traversodontidae): phylogenetic implications, body mass, and lifestyle

Journal of Mammalian Evolution, Journal Year: 2025, Volume and Issue: 32(1)

Published: Jan. 24, 2025

Language: Английский

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Endocranial anatomy of the early prozostrodonts (Eucynodontia: Probainognathia) and the neurosensory evolution in mammal forerunners

The Anatomical Record, Journal Year: 2023, Volume and Issue: 307(4), P. 1442 - 1473

Published: April 5, 2023

Abstract Prozostrodon brasiliensis and Therioherpeton cargnini are non‐mammaliaform cynodonts that lived ~233 million years ago (late Carnian, Late Triassic) in western Gondwana. They represent some of the earliest divergent members clade Prozostrodontia, which includes “tritheledontids”, tritylodontids, “brasilodontids”, mammaliaforms (including Mammalia as crown group). Here, we studied endocranial anatomy (cranial endocast, nerves, vessels, ducts, ear region, nasal cavity) these two species. Our findings suggest during early prozostrodonts had a brain with well‐developed olfactory bulbs, expanded cerebral hemispheres divided by interhemispheric sulcus, absence an unossified zone pineal body. The morphology maxillary canal represents necessary condition for presence facial vibrissae. A slight decrease encephalization is observed at origin Prozostrodontia. This new anatomical information provides evidence evolution traits first prozotrodonts, Triassic lineage culminated mammals.

Language: Английский

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Synchrotron X-ray Studies of the Structural and Functional Hierarchies in Mineralised Human Dental Enamel: A State-of-the-Art Review

Dentistry Journal, Journal Year: 2023, Volume and Issue: 11(4), P. 98 - 98

Published: April 7, 2023

Hard dental tissues possess a complex hierarchical structure that is particularly evident in enamel, the most mineralised substance human body. Its and interlinked organisation at Ångstrom (crystal lattice), nano-, micro-, macro-scales result of evolutionary optimisation for mechanical functional performance: hardness stiffness, fracture toughness, thermal, chemical resistance. Understanding physical-chemical-structural relationships each scale requires application appropriately sensitive resolving probes. Synchrotron X-ray techniques offer possibility to progress significantly beyond capabilities conventional laboratory instruments, i.e., diffractometers, electron atomic force microscopes. The last few decades have witnessed accumulation results obtained from scattering (diffraction), spectroscopy (including polarisation analysis), imaging ptychography tomography). current article presents multi-disciplinary review nearly 40 years discoveries advancements, primarily pertaining study enamel its demineralisation (caries), but also linked investigations other such as dentine, bone, etc. modelling approaches informed by these observations are overviewed. strategic aim present was identify evaluate prospective avenues analysing developing treatments prophylaxis improved health.

Language: Английский

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A complete skull of a stem mammal from the Late Triassic of Brazil illuminates the early evolution of prozostrodontian cynodonts

Journal of Mammalian Evolution, Journal Year: 2023, Volume and Issue: 30(2), P. 299 - 317

Published: Jan. 30, 2023

Language: Английский

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Weighing in on miniaturization: New body mass estimates for Triassic eucynodonts and analyses of body size evolution during the cynodont‐mammal transition

The Anatomical Record, Journal Year: 2024, Volume and Issue: 307(4), P. 1594 - 1612

Published: Jan. 16, 2024

Abstract Body size influences most aspects of an animal's biology, consequently, evolutionary diversification is often accompanied by differentiation body sizes within a lineage. It accepted that miniaturization, or the evolution extremely small sizes, played key role in origin and early different mammalian characters non‐mammaliaform cynodonts. However, while there are multiple studies on biomechanical, behavioral, physiological consequences smaller few explore processes lead to them. Here, we use mass as universal measurement phylogenetic comparative analyses Cynodontia, focusing cynodont‐mammal transition, test miniaturization hypothesis for Mammaliaformes. We estimated masses 29 species, ranging from Theriocephalia Mammaliaformes, providing largest collection Triassic cynodont estimates know of, used these disparity through time RR phylo . Unexpectedly, our results did not support hypothesis. Even though fell during Late Triassic, remained lower than expected under purely Brownian motion model up until Early Jurassic, found rates were significantly prozostrodontians leading first Mammaliaformes other lineages. Evolution higher medium large‐sized taxa, indicating was changing more rapidly those lineages probably persistent plesiomorphic character‐state Cynodontia.

Language: Английский

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Craniodental anatomy in Permian–Jurassic Cynodontia and Mammaliaformes (Synapsida, Therapsida) as a gateway to defining mammalian soft tissue and behavioural traits

Philosophical Transactions of the Royal Society B Biological Sciences, Journal Year: 2023, Volume and Issue: 378(1880)

Published: May 15, 2023

Mammals are diagnosed by more than 30 osteological characters (e.g. squamosal-dentary jaw joint, three inner ear ossicles, etc.) that readily preserved in the fossil record. However, it is suite of physiological, soft tissue and behavioural endothermy, hair, lactation, isocortex parental care), evolutionary origins which have eluded scholars for decades, most prominently distinguishes living mammals from other amniotes. Here, we review recent works illustrate how changes concentrated cranial dental morphology mammalian ancestors, Permian–Jurassic Cynodontia Mammaliaformes, can potentially be used to document origin some crucial defining features mammals. We discuss these traits highly integrated, their evolution intermingled with craniodental traits, thus enabling tracing previously out-of-reach phylogenetic history. Most proxies, such as maxillary canal, bony labyrinth replacement only recently became easily accessible—thanks, large part, widespread use X-ray microtomography scanning palaeontology—because they linked internal characters. This article part theme issue ‘The skull: development, structure function’.

Language: Английский

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Mandibular anatomy of a new specimen of a prozostrodontian cynodont (Eucynodontia: Probainognathia) from the Upper Triassic of Brazil

The Science of Nature, Journal Year: 2025, Volume and Issue: 112(1)

Published: Jan. 14, 2025

Language: Английский

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Adaptive landscapes unveil the complex evolutionary path to mammalian forelimb function and posture

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: March 13, 2024

Abstract The ‘sprawling-parasagittal’ postural transition is a key part of mammalian evolution, associated with sweeping reorganization the postcranial skeleton in mammals compared to their forebears, non-mammalian synapsids. However, disputes over forelimb function fossil synapsids render precise nature controversial. We shed new light on origins posture, using evolutionary adaptive landscapes integrate 3D humerus shape and functional performance data across taxonomically comprehensive sample extant comparators. find that earliest pelycosaur-grade had unique mode sprawling, intermediate between reptiles monotremes. Subsequent evolution synapsid form showed little evidence direct progression from sprawling pelycosaurs parasagittal mammals. Instead, posture was evolutionarily labile, ecological diversification successive radiations accompanied by variation morphofunctional traits. Further, frequently evolve towards postures, diverging reconstructed optimal path; path only aligns becoming increasingly derived cynodonts. support for habitual postures stem therians, implying evolved radiated distinct trait combinations most recorded history.

Language: Английский

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