A reassessment of the anatomy and taxonomy of the Ischigualastian South American aetosaurs (Archosauria: Pseudosuchia)

Autores
Ezcurra, Martin D.; Desojo, Julia Brenda
Año de publicación
2010
Idioma
inglés
Tipo de recurso
documento de conferencia
Estado
versión publicada
Descripción
The Ischigualastian (late Carnian-middle Norian, Late Triassic) South American aetosaur record is dominated by the genus Aetosauroides. Two different species have been reported, the Argentinean Aetosauroides scagliai Casamiquela and the Brazilian "Aetosauroides subsulcatus" Zacarias. Although both species were regarded as synonymous with Stagonolepis robertsoni Agassiz, this synonymy has not been followed by most researchers and is also dismissed here. As recently pointed out, no features distinguish "A. subsulcatus" from A. scagliai and a unique combination of apomorphies supports their synonymy. Additionally, an undescribed aetosaur specimen (CPE2 168) from the Hyperodapedon Assemblage Zone of the Brazilian Santa Maria Formation is considered here as a new genus. CPE2 168 consists of a fragmentary postcranium including one cervical, nine dorsal, and one caudal vertebrae, right scapula, humerus, tibia, metatarsals, pedal phalanges, and paramedian osteoderms. CPE2 168 differs from A. scagliai (= "A. subsulcatus") on the following characters: cervical vertebrae lacking ventral keels, dorsal vertebrae with hyposphenes and hypantra, fossae anterolateral to the neural spine base, low neural spines and without vertebral laminae and lateral fossae below the neurocentral suture. Thus, a new taxon is added to the list of South American Ischigualastian aetosaurs, which is currently composed of two species. As also is the case with proterochampsids, herrerasaurids, and Hyperodapedon sanjuanensis (Sill) among others, the Ischigualastian aetosaur record supports at least some degree of South American endemism during this time-span. Finally, although the genus Stagonolepis has been employed as an index taxon for the Adamanian land vertebrate faunachron, this genus is currently restricted to the Late Triassic of Europe and North America but absent in South America, and no overlapping genus or species of aetosaur are shared between South America and other landmasses. Accordingly, the record of aetosaurs is not useful at the time of performing global biostratigraphical correlations of Late Triassic assemblages.
Simposio III: Ecosistemas triásicos, su paleobiología y el contexto de recuperación de la gran extinción
Facultad de Ciencias Naturales y Museo
Materia
Ciencias Naturales
Paleontología
Nivel de accesibilidad
acceso abierto
Condiciones de uso
http://creativecommons.org/licenses/by-nc-sa/4.0/
Repositorio
SEDICI (UNLP)
Institución
Universidad Nacional de La Plata
OAI Identificador
oai:sedici.unlp.edu.ar:10915/16650

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spelling A reassessment of the anatomy and taxonomy of the Ischigualastian South American aetosaurs (Archosauria: Pseudosuchia)Ezcurra, Martin D.Desojo, Julia BrendaCiencias NaturalesPaleontologíaThe Ischigualastian (late Carnian-middle Norian, Late Triassic) South American aetosaur record is dominated by the genus Aetosauroides. Two different species have been reported, the Argentinean Aetosauroides scagliai Casamiquela and the Brazilian "Aetosauroides subsulcatus" Zacarias. Although both species were regarded as synonymous with Stagonolepis robertsoni Agassiz, this synonymy has not been followed by most researchers and is also dismissed here. As recently pointed out, no features distinguish "A. subsulcatus" from A. scagliai and a unique combination of apomorphies supports their synonymy. Additionally, an undescribed aetosaur specimen (CPE2 168) from the Hyperodapedon Assemblage Zone of the Brazilian Santa Maria Formation is considered here as a new genus. CPE2 168 consists of a fragmentary postcranium including one cervical, nine dorsal, and one caudal vertebrae, right scapula, humerus, tibia, metatarsals, pedal phalanges, and paramedian osteoderms. CPE2 168 differs from A. scagliai (= "A. subsulcatus") on the following characters: cervical vertebrae lacking ventral keels, dorsal vertebrae with hyposphenes and hypantra, fossae anterolateral to the neural spine base, low neural spines and without vertebral laminae and lateral fossae below the neurocentral suture. Thus, a new taxon is added to the list of South American Ischigualastian aetosaurs, which is currently composed of two species. As also is the case with proterochampsids, herrerasaurids, and Hyperodapedon sanjuanensis (Sill) among others, the Ischigualastian aetosaur record supports at least some degree of South American endemism during this time-span. Finally, although the genus Stagonolepis has been employed as an index taxon for the Adamanian land vertebrate faunachron, this genus is currently restricted to the Late Triassic of Europe and North America but absent in South America, and no overlapping genus or species of aetosaur are shared between South America and other landmasses. Accordingly, the record of aetosaurs is not useful at the time of performing global biostratigraphical correlations of Late Triassic assemblages.Simposio III: Ecosistemas triásicos, su paleobiología y el contexto de recuperación de la gran extinciónFacultad de Ciencias Naturales y Museo2010info:eu-repo/semantics/conferenceObjectinfo:eu-repo/semantics/publishedVersionResumenhttp://purl.org/coar/resource_type/c_5794info:ar-repo/semantics/documentoDeConferenciaapplication/pdfhttp://sedici.unlp.edu.ar/handle/10915/16650enginfo:eu-repo/semantics/altIdentifier/isbn/978-987-95849-7-2info:eu-repo/semantics/reference/hdl/10915/25738info:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by-nc-sa/4.0/Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)reponame:SEDICI (UNLP)instname:Universidad Nacional de La Platainstacron:UNLP2025-09-29T10:52:58Zoai:sedici.unlp.edu.ar:10915/16650Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292025-09-29 10:52:58.413SEDICI (UNLP) - Universidad Nacional de La Platafalse
dc.title.none.fl_str_mv A reassessment of the anatomy and taxonomy of the Ischigualastian South American aetosaurs (Archosauria: Pseudosuchia)
title A reassessment of the anatomy and taxonomy of the Ischigualastian South American aetosaurs (Archosauria: Pseudosuchia)
spellingShingle A reassessment of the anatomy and taxonomy of the Ischigualastian South American aetosaurs (Archosauria: Pseudosuchia)
Ezcurra, Martin D.
Ciencias Naturales
Paleontología
title_short A reassessment of the anatomy and taxonomy of the Ischigualastian South American aetosaurs (Archosauria: Pseudosuchia)
title_full A reassessment of the anatomy and taxonomy of the Ischigualastian South American aetosaurs (Archosauria: Pseudosuchia)
title_fullStr A reassessment of the anatomy and taxonomy of the Ischigualastian South American aetosaurs (Archosauria: Pseudosuchia)
title_full_unstemmed A reassessment of the anatomy and taxonomy of the Ischigualastian South American aetosaurs (Archosauria: Pseudosuchia)
title_sort A reassessment of the anatomy and taxonomy of the Ischigualastian South American aetosaurs (Archosauria: Pseudosuchia)
dc.creator.none.fl_str_mv Ezcurra, Martin D.
Desojo, Julia Brenda
author Ezcurra, Martin D.
author_facet Ezcurra, Martin D.
Desojo, Julia Brenda
author_role author
author2 Desojo, Julia Brenda
author2_role author
dc.subject.none.fl_str_mv Ciencias Naturales
Paleontología
topic Ciencias Naturales
Paleontología
dc.description.none.fl_txt_mv The Ischigualastian (late Carnian-middle Norian, Late Triassic) South American aetosaur record is dominated by the genus Aetosauroides. Two different species have been reported, the Argentinean Aetosauroides scagliai Casamiquela and the Brazilian "Aetosauroides subsulcatus" Zacarias. Although both species were regarded as synonymous with Stagonolepis robertsoni Agassiz, this synonymy has not been followed by most researchers and is also dismissed here. As recently pointed out, no features distinguish "A. subsulcatus" from A. scagliai and a unique combination of apomorphies supports their synonymy. Additionally, an undescribed aetosaur specimen (CPE2 168) from the Hyperodapedon Assemblage Zone of the Brazilian Santa Maria Formation is considered here as a new genus. CPE2 168 consists of a fragmentary postcranium including one cervical, nine dorsal, and one caudal vertebrae, right scapula, humerus, tibia, metatarsals, pedal phalanges, and paramedian osteoderms. CPE2 168 differs from A. scagliai (= "A. subsulcatus") on the following characters: cervical vertebrae lacking ventral keels, dorsal vertebrae with hyposphenes and hypantra, fossae anterolateral to the neural spine base, low neural spines and without vertebral laminae and lateral fossae below the neurocentral suture. Thus, a new taxon is added to the list of South American Ischigualastian aetosaurs, which is currently composed of two species. As also is the case with proterochampsids, herrerasaurids, and Hyperodapedon sanjuanensis (Sill) among others, the Ischigualastian aetosaur record supports at least some degree of South American endemism during this time-span. Finally, although the genus Stagonolepis has been employed as an index taxon for the Adamanian land vertebrate faunachron, this genus is currently restricted to the Late Triassic of Europe and North America but absent in South America, and no overlapping genus or species of aetosaur are shared between South America and other landmasses. Accordingly, the record of aetosaurs is not useful at the time of performing global biostratigraphical correlations of Late Triassic assemblages.
Simposio III: Ecosistemas triásicos, su paleobiología y el contexto de recuperación de la gran extinción
Facultad de Ciencias Naturales y Museo
description The Ischigualastian (late Carnian-middle Norian, Late Triassic) South American aetosaur record is dominated by the genus Aetosauroides. Two different species have been reported, the Argentinean Aetosauroides scagliai Casamiquela and the Brazilian "Aetosauroides subsulcatus" Zacarias. Although both species were regarded as synonymous with Stagonolepis robertsoni Agassiz, this synonymy has not been followed by most researchers and is also dismissed here. As recently pointed out, no features distinguish "A. subsulcatus" from A. scagliai and a unique combination of apomorphies supports their synonymy. Additionally, an undescribed aetosaur specimen (CPE2 168) from the Hyperodapedon Assemblage Zone of the Brazilian Santa Maria Formation is considered here as a new genus. CPE2 168 consists of a fragmentary postcranium including one cervical, nine dorsal, and one caudal vertebrae, right scapula, humerus, tibia, metatarsals, pedal phalanges, and paramedian osteoderms. CPE2 168 differs from A. scagliai (= "A. subsulcatus") on the following characters: cervical vertebrae lacking ventral keels, dorsal vertebrae with hyposphenes and hypantra, fossae anterolateral to the neural spine base, low neural spines and without vertebral laminae and lateral fossae below the neurocentral suture. Thus, a new taxon is added to the list of South American Ischigualastian aetosaurs, which is currently composed of two species. As also is the case with proterochampsids, herrerasaurids, and Hyperodapedon sanjuanensis (Sill) among others, the Ischigualastian aetosaur record supports at least some degree of South American endemism during this time-span. Finally, although the genus Stagonolepis has been employed as an index taxon for the Adamanian land vertebrate faunachron, this genus is currently restricted to the Late Triassic of Europe and North America but absent in South America, and no overlapping genus or species of aetosaur are shared between South America and other landmasses. Accordingly, the record of aetosaurs is not useful at the time of performing global biostratigraphical correlations of Late Triassic assemblages.
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