Cranial anatomy of the aetosaur <i>Paratypothorax andressorum</i> Long & Ballew, 1985, from the Upper Triassic of Germany and its bearing on aetosaur phylogeny

Autores
Schoch, Rainer R.; Desojo, Julia Brenda
Año de publicación
2016
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
The large aetosaur Paratypothorax andressorum has so far been known only by its osteoderms. Here we describe for the first time the skull of a complete, articulated specimen of this taxon that was found in the type horizon at Murrhardt, southwestern Germany. Paratypothorax andressorum has the following cranial autapomorphies: (1) upper jaw margin with deep notch between premaxilla and maxilla, (2) maxilla-lacrimal suture with finger-like projection, (3) upper temporal fenestra triangular, and (4) first paramedian cervical osteoderms narrow and oval, much smaller than second row. Apart from these features, the skull of P. andressorum closely resembles that of the small aetosaur Aetosaurus ferratus known from the same horizons, despite major differences in the morphology of osteoderms. Both taxa share (1) the pointed, beak-shaped premaxilla which expands only gently anterior to the nasal, (2) maxilla and lacrimal excluding jugal from margin of antorbital fenestra, (3) exclusion of squamosal from margin of infratemporal fenestra, and (4) posterior part of jugal not downturned. Phylogenetic analysis reveals poorly resolved relationships within Aetosauria, but exclusion of a problematic taxon Coahomasuchus results in a much better resolution, with Paratypothorax to nest with Rioarribasuchus, Tecovasuchus, Typothorax, and Redondasuchus within a monophyletic Typothoracinae. Interestingly, Aetosaurus and Stenomyti form successive sister taxa of this clade rather than fall within an aetosaurine grade of basal aetosaurs, as suggested by previous authors.The resemblance of Paratypothorax and Aetosaurus in many cranial features, their close relationship as suggested by the present analysis, and the immature state of all available Aetosaurus specimens suggest two new alternative hypotheses: (1) Aetosaurus is the juvenile of a close relative of Paratypothorax or (2) it is itself the juvenile of Paratypothorax.
Facultad de Ciencias Naturales y Museo
Materia
Ciencias Naturales
Aetosaurus
Archosauria
Löwenstein Formation
Norian
Pseudosuchia
Nivel de accesibilidad
acceso abierto
Condiciones de uso
http://creativecommons.org/licenses/by-nc/4.0/
Repositorio
SEDICI (UNLP)
Institución
Universidad Nacional de La Plata
OAI Identificador
oai:sedici.unlp.edu.ar:10915/108331

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spelling Cranial anatomy of the aetosaur <i>Paratypothorax andressorum</i> Long & Ballew, 1985, from the Upper Triassic of Germany and its bearing on aetosaur phylogenySchoch, Rainer R.Desojo, Julia BrendaCiencias NaturalesAetosaurusArchosauriaLöwenstein FormationNorianPseudosuchiaThe large aetosaur Paratypothorax andressorum has so far been known only by its osteoderms. Here we describe for the first time the skull of a complete, articulated specimen of this taxon that was found in the type horizon at Murrhardt, southwestern Germany. Paratypothorax andressorum has the following cranial autapomorphies: (1) upper jaw margin with deep notch between premaxilla and maxilla, (2) maxilla-lacrimal suture with finger-like projection, (3) upper temporal fenestra triangular, and (4) first paramedian cervical osteoderms narrow and oval, much smaller than second row. Apart from these features, the skull of P. andressorum closely resembles that of the small aetosaur Aetosaurus ferratus known from the same horizons, despite major differences in the morphology of osteoderms. Both taxa share (1) the pointed, beak-shaped premaxilla which expands only gently anterior to the nasal, (2) maxilla and lacrimal excluding jugal from margin of antorbital fenestra, (3) exclusion of squamosal from margin of infratemporal fenestra, and (4) posterior part of jugal not downturned. Phylogenetic analysis reveals poorly resolved relationships within Aetosauria, but exclusion of a problematic taxon Coahomasuchus results in a much better resolution, with Paratypothorax to nest with Rioarribasuchus, Tecovasuchus, Typothorax, and Redondasuchus within a monophyletic Typothoracinae. Interestingly, Aetosaurus and Stenomyti form successive sister taxa of this clade rather than fall within an aetosaurine grade of basal aetosaurs, as suggested by previous authors.The resemblance of Paratypothorax and Aetosaurus in many cranial features, their close relationship as suggested by the present analysis, and the immature state of all available Aetosaurus specimens suggest two new alternative hypotheses: (1) Aetosaurus is the juvenile of a close relative of Paratypothorax or (2) it is itself the juvenile of Paratypothorax.Facultad de Ciencias Naturales y Museo2016info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionArticulohttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdf73-95http://sedici.unlp.edu.ar/handle/10915/108331enginfo:eu-repo/semantics/altIdentifier/issn/0077-7749info:eu-repo/semantics/altIdentifier/doi/10.1127/njgpa/2016/0542info:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by-nc/4.0/Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)reponame:SEDICI (UNLP)instname:Universidad Nacional de La Platainstacron:UNLP2025-09-29T11:24:32Zoai:sedici.unlp.edu.ar:10915/108331Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292025-09-29 11:24:33.037SEDICI (UNLP) - Universidad Nacional de La Platafalse
dc.title.none.fl_str_mv Cranial anatomy of the aetosaur <i>Paratypothorax andressorum</i> Long & Ballew, 1985, from the Upper Triassic of Germany and its bearing on aetosaur phylogeny
title Cranial anatomy of the aetosaur <i>Paratypothorax andressorum</i> Long & Ballew, 1985, from the Upper Triassic of Germany and its bearing on aetosaur phylogeny
spellingShingle Cranial anatomy of the aetosaur <i>Paratypothorax andressorum</i> Long & Ballew, 1985, from the Upper Triassic of Germany and its bearing on aetosaur phylogeny
Schoch, Rainer R.
Ciencias Naturales
Aetosaurus
Archosauria
Löwenstein Formation
Norian
Pseudosuchia
title_short Cranial anatomy of the aetosaur <i>Paratypothorax andressorum</i> Long & Ballew, 1985, from the Upper Triassic of Germany and its bearing on aetosaur phylogeny
title_full Cranial anatomy of the aetosaur <i>Paratypothorax andressorum</i> Long & Ballew, 1985, from the Upper Triassic of Germany and its bearing on aetosaur phylogeny
title_fullStr Cranial anatomy of the aetosaur <i>Paratypothorax andressorum</i> Long & Ballew, 1985, from the Upper Triassic of Germany and its bearing on aetosaur phylogeny
title_full_unstemmed Cranial anatomy of the aetosaur <i>Paratypothorax andressorum</i> Long & Ballew, 1985, from the Upper Triassic of Germany and its bearing on aetosaur phylogeny
title_sort Cranial anatomy of the aetosaur <i>Paratypothorax andressorum</i> Long & Ballew, 1985, from the Upper Triassic of Germany and its bearing on aetosaur phylogeny
dc.creator.none.fl_str_mv Schoch, Rainer R.
Desojo, Julia Brenda
author Schoch, Rainer R.
author_facet Schoch, Rainer R.
Desojo, Julia Brenda
author_role author
author2 Desojo, Julia Brenda
author2_role author
dc.subject.none.fl_str_mv Ciencias Naturales
Aetosaurus
Archosauria
Löwenstein Formation
Norian
Pseudosuchia
topic Ciencias Naturales
Aetosaurus
Archosauria
Löwenstein Formation
Norian
Pseudosuchia
dc.description.none.fl_txt_mv The large aetosaur Paratypothorax andressorum has so far been known only by its osteoderms. Here we describe for the first time the skull of a complete, articulated specimen of this taxon that was found in the type horizon at Murrhardt, southwestern Germany. Paratypothorax andressorum has the following cranial autapomorphies: (1) upper jaw margin with deep notch between premaxilla and maxilla, (2) maxilla-lacrimal suture with finger-like projection, (3) upper temporal fenestra triangular, and (4) first paramedian cervical osteoderms narrow and oval, much smaller than second row. Apart from these features, the skull of P. andressorum closely resembles that of the small aetosaur Aetosaurus ferratus known from the same horizons, despite major differences in the morphology of osteoderms. Both taxa share (1) the pointed, beak-shaped premaxilla which expands only gently anterior to the nasal, (2) maxilla and lacrimal excluding jugal from margin of antorbital fenestra, (3) exclusion of squamosal from margin of infratemporal fenestra, and (4) posterior part of jugal not downturned. Phylogenetic analysis reveals poorly resolved relationships within Aetosauria, but exclusion of a problematic taxon Coahomasuchus results in a much better resolution, with Paratypothorax to nest with Rioarribasuchus, Tecovasuchus, Typothorax, and Redondasuchus within a monophyletic Typothoracinae. Interestingly, Aetosaurus and Stenomyti form successive sister taxa of this clade rather than fall within an aetosaurine grade of basal aetosaurs, as suggested by previous authors.The resemblance of Paratypothorax and Aetosaurus in many cranial features, their close relationship as suggested by the present analysis, and the immature state of all available Aetosaurus specimens suggest two new alternative hypotheses: (1) Aetosaurus is the juvenile of a close relative of Paratypothorax or (2) it is itself the juvenile of Paratypothorax.
Facultad de Ciencias Naturales y Museo
description The large aetosaur Paratypothorax andressorum has so far been known only by its osteoderms. Here we describe for the first time the skull of a complete, articulated specimen of this taxon that was found in the type horizon at Murrhardt, southwestern Germany. Paratypothorax andressorum has the following cranial autapomorphies: (1) upper jaw margin with deep notch between premaxilla and maxilla, (2) maxilla-lacrimal suture with finger-like projection, (3) upper temporal fenestra triangular, and (4) first paramedian cervical osteoderms narrow and oval, much smaller than second row. Apart from these features, the skull of P. andressorum closely resembles that of the small aetosaur Aetosaurus ferratus known from the same horizons, despite major differences in the morphology of osteoderms. Both taxa share (1) the pointed, beak-shaped premaxilla which expands only gently anterior to the nasal, (2) maxilla and lacrimal excluding jugal from margin of antorbital fenestra, (3) exclusion of squamosal from margin of infratemporal fenestra, and (4) posterior part of jugal not downturned. Phylogenetic analysis reveals poorly resolved relationships within Aetosauria, but exclusion of a problematic taxon Coahomasuchus results in a much better resolution, with Paratypothorax to nest with Rioarribasuchus, Tecovasuchus, Typothorax, and Redondasuchus within a monophyletic Typothoracinae. Interestingly, Aetosaurus and Stenomyti form successive sister taxa of this clade rather than fall within an aetosaurine grade of basal aetosaurs, as suggested by previous authors.The resemblance of Paratypothorax and Aetosaurus in many cranial features, their close relationship as suggested by the present analysis, and the immature state of all available Aetosaurus specimens suggest two new alternative hypotheses: (1) Aetosaurus is the juvenile of a close relative of Paratypothorax or (2) it is itself the juvenile of Paratypothorax.
publishDate 2016
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rights_invalid_str_mv http://creativecommons.org/licenses/by-nc/4.0/
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