Reassessment of cf. Halticosaurus orbitoangulatus from the Upper Triassic (Norian) of Germany – a pseudosuchian, not a dinosaur HANS-DIETER SUES FLS 1 * and RAINER R. SCHOCH 2 1 Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, MRC 121, P.O. Box 37012, Washington, DC 20013-7012, USA 2 Staatliches Museum für Naturkunde Stuttgart, Rosenstein 1, D-70191 Stuttgart, Germany Received 4 October 2012; revised 31 January 2013; accepted for publication 19 March 2013 The holotype of cf. Halticosaurus orbitoangulatus Huene, 1932, comprises an incomplete and macerated but associated skull of an archosaurian reptile from the middle (second) Stubensandstein (middle Löwenstein Formation; Upper Triassic: Norian) of Baden-Württemberg, Germany. It was originally interpreted as a theropod dinosaur but more recently it has been suggested that this taxon has crocodylomorph affinities. Detailed preparation of the holotype of cf. H. orbitoangulatus has revealed much new anatomical information and permitted reassessment of its affinities. The maxilla lacks both a distinct antorbital fossa and a medial bony lamina bordering the antorbital fenestra. The lateral surface of the dentary bears a pronounced horizontal ridge. The squamosal differs from that of basal crocodylomorphs in being L-shaped rather than arcuate in dorsal view, lacking a dorsolateral overhang, and lacking an interlocking contact with the paroccipital process as, for example, in the basal crocodylomorph Saltoposuchus connectens from the same horizon and locality. Phylogenetic analysis placed cf. H. orbitoangulatus amongst loricatan pseudosuchians (but not amongst Crocodylomorpha) rather than amongst theropod dinosaurs. The holotype of cf. H. orbitoangulatus represents a previously unrecognized taxon of loricatan pseudosuchian, which is here named Apatosuchus orbitoangulatus and set apart from other known Norian-age non-crocodylomorph loricatans by its apparently much smaller size. © 2013 The Linnean Society of London, Zoological Journal of the Linnean Society, 2013, 168, 859–872. doi: 10.1111/zoj.12038 ADDITIONAL KEYWORDS: Archosauria – Baden-Württemberg – Loricata – Löwenstein Formation – Paracrocodylomorpha. INTRODUCTION Non-avian theropod dinosaurs were the dominant predators in terrestrial ecosystems for much of the Mesozoic Era. The oldest known undisputed members of this group date from the Norian stage of the Late Triassic (Nesbitt, Irmis & Parker, 2007). However, the existence of late Carnian representatives of Sauro- podomorpha (Martínez & Alcober, 2009; Cabreira et al., 2011; Martinez et al., 2011), the sister taxon of Theropoda, implies that the latter clade must have the same age. Late Triassic continental strata of the Middle Keuper in Baden-Württemberg, Germany, have yielded numerous, well-preserved skeletal remains of the basal sauropodomorph dinosaur Efraasia minor (see Yates, 2003) but surprisingly few fossils of theropods (Huene, 1907–1908, 1932; Rauhut & Hungerbühler, 2000). Amongst the latter are several specimens from the middle (second) Stubensandstein (Löwenstein Formation; Norian) of the Stromberg region in northern Baden-Württemberg (Fig. 1). Almost all the specimens of dinosaurs and crocody- lomorph archosaurs known from the Löwenstein For- mation were recovered from a disused sandstone quarry known as the ‘Weisser Steinbruch’ and located *Corresponding author. E-mail: suesh@si.edu Zoological Journal of the Linnean Society, 2013, 168, 859–872. With 7 figures © 2013 The Linnean Society of London, Zoological Journal of the Linnean Society, 2013, 168, 859–872 859 Downloaded from https://academic.oup.com/zoolinnean/article-abstract/168/4/859/2420732 by guest on 23 May 2020