Shuvosauridae Chatterjee, 1993

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 : 199

Shuvosauridae Chatterjee, 1993 (fig. 53)

DEFINITION: Node: The least inclusive clade containing Shuvosaurus inexpectatus Chatterjee, 1993 , and Sillosuchus longicervix Alcober and Parrish, 1997 (new).

TEMPORAL RANGE: Late Triassic (?Carnian–early Norian, Sillosuchus longicervix Alcober and Parrish, 1997 ) to latest Triassic (late Norian–?Rhaetian, Effigia okeeffeae Nesbitt and Norell, 2006 ).

SUPPORT: (1) Pneumatic features (5 pleurocoels) in the anterior portion of the cervical centrum present as deep fossae (188-1). (2) Rimmed depression on the posterior part of the cervical centrum (189-1)*. (3) Sacral ribs shared between two sacral vertebrae (208-1). (4) Entire anterior margin of the scapula straight/convex or partially concave (217-0). (5) Posteroventral portion of the coracoid smooth (225-0)*. (6) Proximal portion of the humerus expanded less than twice the width of the midshaft of the humerus (236-1)*.

Other possible synapomorphies: AC- CTRAN: Anterior portion of the frontal tapers anteriorly along the midline (43-1); postfrontal absent (44-1); upper temporal fenestrae separated by a ‘‘sagittal crest’’ (59- 2); postorbital bar composed mostly of the postorbital (67-1). Also present in aetosaurs; longitudinal ridge on the body of the jugal absent (75-0); distal articular margin of the quadrate largely concave and corresponding convex articular surface of the articular (81- 1); quadrate angled anteroventrally (82-1); basipterygoid processes directed anteriorly or ventrally at their distal tips (93-0); foramina for entrance of cerebral branches of internal carotid artery into the braincase positioned on the anterolateral surface (95-2); parabasisphenoid, between basal tubera and basipterygoid processes significantly elongated at least 1.5 times longer than wide (103-1); paroccipital processes directed ventrolaterally (110-1). Only known in Shuvosaurus ; exoccipitals do not meet along the midline on the floor of the endocranial cavity (115-1); articular without dorsomedial projection posterior to the glenoid fossa (156-0); foramen on the medial side of the articular absent (159-0); mandibular fenestra length greater than half the length of the mandible (162-1); surangular foramen large (163-1); ectepicondylar flange of the humerus absent (234-1); metatarsal III subequal to metatarsal II (390- 1). None of these characters are known in Sillosuchus . DELTRAN: Primordial trunk vertebrae incorporated into the sacrum (205-1); crest dorsal to the supraacetabular crest of the ilium as a thin ridge (267-1).