Turfanosuchus dabanensis Young, 1973

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 : 21-22

Turfanosuchus dabanensis Young, 1973

AGE: Middle Triassic ( Young, 1973).

OCCURRENCE: Vertebrate Fossil Bed IV (Kannemeyeriid Zone), lower Kelamayi Formation, Taoshuyuanzi, about 30 km northwest of Turfan Basin, Xinjiang.

HOLOTYPE: IVPP V3237, much of a disarticulated skeleton.

REMARKS: Turfanosuchus is one of the oldest archosauriforms with a nearly complete skull and a partial skeleton. The partial skeleton was reassembled, the missing portions were sculpted, and the specimen was encased in plaster and then painted. The processing of the specimen for display purposes concealed details of the skeleton and obscured recognition of which bones were fossils and which were sculpted. For example, Young illustrated a nearly complete right manus and pes ( Young, 1973: fig. 2). A recent inspection by me suggests that only the proximal portions of the metatarsals are preserved, whereas the manus and most of the pes are sculpted. Recently, Wu and Russell (2001) described reprepared material including the skull, femur, ilium, pubis, humerus, a newly discovered osteoderm, calcaneum, and astragalus. The specimens were fixed back to the mount after the completion of their study. The morphology of the astragalus could not be confirmed in this study and is not scored here.

The systematic position of Turfanosuchus has been debated recently and was included in only in only a few phylogenetic analysis thus far ( Parrish, 1993; Dilkes and Sues, 2009). Parrish (1993) found Turfanosuchus well nested among crocodylian-line archosaurs. In a point-by-point response to the character scoring of Parrish (1993), Wu and Russell (2001) concluded that Turfanosuchus is neither a suchian nor a crurotarsan (5 crocodylian-line archosaur in their meaning). Even though the analysis of Parrish (1993) was fraught with problems, Wu and Russell’s (2001) detailed discussion of why Turfanosuchus is not an archosaur warrants further comment (character number from Wu and Russell, 2001, in parentheses):

(4) Presence of palatal teeth: Even though palatal teeth are present in Turfanosuchus and many non-archosaurian diapsids, palatal teeth are present in the archosaur Eoraptor . Furthermore, the pterygoid teeth in Turfanosuchus are exceedingly small and well spaced; therefore, pterygoid teeth may not be recognized in poorly preserved taxa, disarticulated taxa, or taxa without palates preserved.

(5) Foramina for internal carotid arteries enter the body of the basisphenoid ventral to the basipterygoid processes: The foramina for the entrance of the internal carotid arteries enter ventrally in Turfanosuchus , Euparkeria (SAM 5867), proterochampsians (e.g., Chanaresuchus, PVL 4647), and other non-archosaurian archosauriforms. Previously, it was thought that the internal carotid arteries entered laterally in archosaurs (see Gower and Sennikov, 1996; Gower and Walker, 2002). However, new discoveries, including Arizonasaurus ( Gower and Nesbitt, 2006) , Qianosuchus ( Li et al., 2006) and Silesaurus ( Dzik, 2003) , showed that a ventral entrance for the internal carotid arteries occurs within Archosauria.

(7) Calcaneal tuber shaft broader than tall: Wu and Russell (2001) confused the measurements of the tuber shaft with the dimensions of the distal end of the tuber. In fact, the shaft of the tuber is wider than tall (contra Wu and Russell, 2001).

(8) Calcaneal tuber not flared distally: The distal end of the calcaneum tuber of Turfanosuchus is flared (contra Wu and Russell, 2001).

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Most recently, Dilkes and Sues (2009) found Turfanosuchus outside Archosauria giving support to the hypothesis of Wu and Russell (2001).

KEY REFERENCES: Young, 1973; Parrish, 1993; Wu and Russell, 2001.