Aetosauria Marsh, 1884

Nesbitt, Sterling J., 2011, The Early Evolution Of Archosaurs: Relationships And The Origin Of Major Clades, Bulletin of the American Museum of Natural History 2011 (352), pp. 1-292 : 195-196

Aetosauria Marsh, 1884

ORIGINAL DEFINITION: All crurotarsans more closely related to Desmatosuchus than

the immediate sister group, recognizing that the sister group may be rauisuchians, prestosuchians, or another suchian taxon ( Heckert and Lucas, 2000).

REVISED DEFINITION: Stem: The most inclusive clade containing Aetosaurus ferratus Fraas, 1877 , and Desmatosuchus haplocerus Cope, 1892 , than to Rutiodon carolinensis Emmons, 1856 , Postosuchus kirkpatricki Chatterjee, 1985 , Prestosuchus chiniquensis Huene, 1942 , Poposaurus gracilis Mehl, 1915 , Crocodylus niloticus Laurenti, 1768 , Gracilisuchus stipanicicorum Romer, 1972c , and Revueltosaurus callenderi Hunt, 1989 (modified from Parker, 2007).

TEMPORAL RANGE: Late Triassic (?Carnian–early Norian, Aetosauroides scagliai Casamiquela, 1960 , to?late Norian ( Redondasuchus reseri Hunt and Lucas, 1991 )

SUPPORT: The monophyly of Aetosauria has never been contested. Here, Aetosauria is supported by the following unambiguous synapomorphies: (1) Premaxilla teeth absent in the anterior portion of the premaxilla (7-1)*. (2) Anterodorsal margin of the maxilla borders the external naris (24-1). (3) Concave anterodorsal margin at the base of the dorsal process of the maxilla (25-1). (4) Quadratojugal forms more than 80% of the posterior border of the lower temporal fenestra (45-1). (5) Straight occipital margin of the parietals in dorsal view (61-1). (6) Posterolateral (5 occipital) processes of the parietals anteriorly inclined greater than 45 ° (62-1). (7) Quadrate angled anteroventrally (82-1). (8) Lateral exposed supratemporal fenestra (143-1)*. (9) Anterodorsal margin of the dentary dorsally expanded (154-2). (10) Anterior extent of the dentary tapers to a sharp point (155-1)*. (11) Glenoid of the mandible located well ventral of the dorsal margin of the dentary (158-1). (12) Dentary teeth absent in the anterior portion (166-1)*. (13) Tooth crown mesiodistally expanded above root in cheek teeth (171-1).

Other possible synapomorphies: AC- CTRAN: Ventromedial process of the prefrontal present (40-1); absence of an articular foramen on the medial side (159-0); hyposphene-hypantrum accessory intervertebral articulations in the posterior cervical and/or dorsal vertebrae (195-1); ilium ventrolaterally deflected about 45 ° (270-1); attachment site for the M. iliofibularis of the fibula near the mid point between the proximal and distal ends (340-1). DELTRAN: Two paramedian pairs (4 osteoderms per segment) (406-1). The condition is unknown in Revueltosaurus at present.