Euparkeria capensis Broom, 1913

Rauhut, Oliver W. M., 2003, The interrelationships and evolution of basal theropod dinosaurs, Special papers in palaeontology 69, pp. 1-213 : 12

Euparkeria capensis Broom, 1913

Age . Scythian-Anisian.

Occurrence. Cynognathus assemblage zone of the Beaufort Group, South Africa.

Diagnosis. Premaxilla with a vertical, dorsally rounded postnarial process.

Remarks. Ever since its original description ( Broom 1913), Euparkeria ( Text-fig. 4a ) has played a pivotal role in the discussion of archosaur interrelationships. Long believed to be ancestral to dinosaurs and sometimes birds ( Heilmann 1926; Welman 1995), it is now generally considered to be the sister group of the clade comprising all the recent representatives of Archosauria (see Gower and Wilkinson 1996 and references therein). Because of this basal phylogenetic position, its unspecialized morphology and our relatively complete knowledge of its anatomy, Euparkeria is used here as the most basal outgroup to dinosaurs, and it is the taxon used to root the tree.

Figures

text-fig. 4. Skull reconstructions of representatives of riassic OTUs in left lateral view, a, Euparkeria capensis, Early Triassic (Scythian-Anisian), Beaufort Group, South Africa; redrawn from Ewer (1965). B, basal ornithischian Lesothosaurus diagnostics, Early Jurassic (Hettangian-Sinemurian), Elliot Formation, Lesotho; redrawn from Sereno (1991b). c, prosauropod sauropodomorph Plateosaurus sp., Late riassic (Norian), Knollenmergel, Germany; based on MB R. 1937. D, Eoraptor lunensis, Late Triassic (Camian), Ischigualasto Formation, Argentina; based on PVSJ 512. E, Herrerasaurus ischigualastensis, Late Triassic (Camian), Ischigualasto Formation, Argentina; redrawn from Sereno and Novas (1993). F, Coelophysis bauri, Late riassic (Norian), Chinle Formation, south-western USA; modified from Paul (1993). G, Lilienstemus lilienstemi, Late riassic (Norian), Knollenmergel, Germany; based on MB R. 2175, unpreserved elements shaded. H, Shuvosaurus inexpectatus, Late riassic (Norian), Dockum Group, Texas, USA; based on TU P 9280. Abbreviations: a, angular; aof, antorbital fenestra; d, dentary; emf, external mandibular fenestra; en, external nares; eo, exoccipital; f, frontal; itf, infratemporal fenestra; j, jugal; 1, lacrimal; m, maxilla; n, nasal; o, orbit; oc, occipital condyle; op, opisthotic; pa, parietal; pd, predentary; pm, premaxilla; pm-mf, premaxillary-maxillary fenestra; po, postorbital; pof, postfrontal; q, quadrate; qf, quadrate foramen; qj, quadratojugal; sa, surangular; saf, surangular foramen; snf, subnarial foramen; sob, supraorbital; soc, supraoccipital; sp, splenial; sq, squamosal; stf, supratemporal fenestra. Scale bars represent 10 mm (a-b) and 50 mm (c-H).