The holotype and only known specimen, PVSJ 882, was discovered in 2006 by Argentine palaeontologist Ricardo N. Martínez during an expedition to the Ischigualasto Formation. It consists of a partial skull lacking the lower jaw, quadrate bones and most of the zygomatic arches and premaxillae.
The generic name Pseudotherium is derived from the Greek words pseudo, meaning "false", and therios, meaning "beast". The specific name argentinus references the country of Argentina where it was found.[1]
Descriptionedit
Pseudotherium would have been a relatively large cynodont; excluding its missing premaxillae, the holotype skull is 69 millimetres (2.7 in) in length. Running along the top of the skull was a prominent sagittal crest (an attachment point for jaw muscles). Like Prozostrodon, a contemporary prozostrodontian from Brazil, it possessed remnants of the prefrontal and postorbital bones. Most mammaliamorphs, on the other hand, lacked any trace of these bones.[1]
The snout of Pseudotherium is long and slender. As the premaxillae are incomplete, no incisors have been preserved. The canines were thin and curved, with unique longitudinal ridges on each side. Behind the canines were nine pairs of postcanine teeth; these were separated from the canines by a short diastema. The postcanines resembled those of Botucaraitherium and the brasilodontids, possessing three main cusps in a roughly symmetrical arrangement. The seventh and eighth postcanines also bore two and three accessory cusps, respectively. Unlike in tritylodontids and mammaliaforms, the roots were incompletely divided.[1]
Classificationedit
The following cladogram is from the phylogenetic analysis of Wallace et al., 2019. Pseudotherium was placed within Mammaliamorpha as the sister taxon of Tritylodontidae, a largely Jurassic group of mammaliamorphs. The authors however noted that Pseudotherium might be more basal than the cladogram suggests, possibly forming a polytomy with tritheledontids, tritylodontids and brasilodontids instead.[1]
A 2023 paper by Stefanello et al., describing a nearly complete new skull of Prozostrodon, recovered Pseudotherium as the sister taxon of that genus, with the two genera forming the clade Prozostrodontidae at the base of Prozostrodontia. A cladogram from that study is shown below:[2]
^ abcdeWallace, Rachel V. S.; Martínez, Ricardo; Rowe, Timothy (2019). "First record of a basal mammaliamorph from the early Late Triassic Ischigualasto Formation of Argentina". PLOS ONE. 14 (8): e0218791. doi:10.1371/journal.pone.0218791.
^Stefanello, M.; Martinelli, A. G.; Müller, R. T.; Dias-da-Silva, S.; Kerber, L. (2023). "A complete skull of a stem mammal from the Late Triassic of Brazil illuminates the early evolution of prozostrodontian cynodonts". Journal of Mammalian Evolution. doi:10.1007/s10914-022-09648-y.
November 27, 2023
pseudotherium, false, beast, extinct, genus, prozostrodontian, cynodonts, from, late, triassic, argentina, contains, species, argentinus, which, first, described, 2019, from, remains, found, peña, member, ischigualasto, formation, ischigualasto, villa, unión, . Pseudotherium false beast is an extinct genus of prozostrodontian cynodonts from the Late Triassic of Argentina It contains one species P argentinus which was first described in 2019 from remains found in the La Pena Member of the Ischigualasto Formation in the Ischigualasto Villa Union Basin 1 PseudotheriumTemporal range Carnian 231 4 Ma PreꞒ Ꞓ O S D C P T J K Pg N 3D rendering of the holotype skullScientific classificationDomain EukaryotaKingdom AnimaliaPhylum ChordataClade SynapsidaClade TherapsidaClade CynodontiaClade ProzostrodontiaGenus PseudotheriumWallace et al 2019Species P argentinusBinomial name Pseudotherium argentinusWallace et al 2019 Contents 1 Discovery and naming 2 Description 3 Classification 4 ReferencesDiscovery and naming editThe holotype and only known specimen PVSJ 882 was discovered in 2006 by Argentine palaeontologist Ricardo N Martinez during an expedition to the Ischigualasto Formation It consists of a partial skull lacking the lower jaw quadrate bones and most of the zygomatic arches and premaxillae The generic name Pseudotherium is derived from the Greek words pseudo meaning false and therios meaning beast The specific name argentinus references the country of Argentina where it was found 1 Description editPseudotherium would have been a relatively large cynodont excluding its missing premaxillae the holotype skull is 69 millimetres 2 7 in in length Running along the top of the skull was a prominent sagittal crest an attachment point for jaw muscles Like Prozostrodon a contemporary prozostrodontian from Brazil it possessed remnants of the prefrontal and postorbital bones Most mammaliamorphs on the other hand lacked any trace of these bones 1 The snout of Pseudotherium is long and slender As the premaxillae are incomplete no incisors have been preserved The canines were thin and curved with unique longitudinal ridges on each side Behind the canines were nine pairs of postcanine teeth these were separated from the canines by a short diastema The postcanines resembled those of Botucaraitherium and the brasilodontids possessing three main cusps in a roughly symmetrical arrangement The seventh and eighth postcanines also bore two and three accessory cusps respectively Unlike in tritylodontids and mammaliaforms the roots were incompletely divided 1 Classification editThe following cladogram is from the phylogenetic analysis of Wallace et al 2019 Pseudotherium was placed within Mammaliamorpha as the sister taxon of Tritylodontidae a largely Jurassic group of mammaliamorphs The authors however noted that Pseudotherium might be more basal than the cladogram suggests possibly forming a polytomy with tritheledontids tritylodontids and brasilodontids instead 1 Probainognathia ProbainognathusProzostrodonTherioherpetonTritheledontidaeMammaliamorpha PseudotheriumTritylodontidaeBotucaraitheriumBrasilodontidaeSinoconodonMammaliaformesA 2023 paper by Stefanello et al describing a nearly complete new skull of Prozostrodon recovered Pseudotherium as the sister taxon of that genus with the two genera forming the clade Prozostrodontidae at the base of Prozostrodontia A cladogram from that study is shown below 2 Probainognathia LumkuiaChiniquodonProbainognathidaeEcteniniidaeProtheriodonProzostrodontia Prozostrodontidae ProzostrodonPseudotheriumTherioherpetonIrajatheriumRiograndiaDiarthrognathusPachygenelusTritylodontidaeBotucaraitheriumBrasilodonMammaliaformesReferences edit a b c d e Wallace Rachel V S Martinez Ricardo Rowe Timothy 2019 First record of a basal mammaliamorph from the early Late Triassic Ischigualasto Formation of Argentina PLOS ONE 14 8 e0218791 doi 10 1371 journal pone 0218791 Stefanello M Martinelli A G Muller R T Dias da Silva S Kerber L 2023 A complete skull of a stem mammal from the Late Triassic of Brazil illuminates the early evolution of prozostrodontian cynodonts Journal of Mammalian Evolution doi 10 1007 s10914 022 09648 y Retrieved from https en wikipedia org w index php title Pseudotherium amp oldid 1143582061, wikipedia, wiki, book, books, library,
