Alectrosaurus olseni, Gilmore, 1933

Holtz, TR jr., 2004, Tyrannosauroidea, The Dinosauria, University of California Press, pp. 111-136 : 2

Alectrosaurus olseni

is known from the Iren Dabasu Formation of Inner Mongolia, People’s Republic of China (Gilmore 1933a); questionably referred material of A. olseni also comes from the Bayanshiree Formation of Mongolia, units of uncertain Late Cretaceous age (most probably younger than Cenomanian and possibly as young as Campanian [Currie and Eberth 1993]). The original material of A. olseni consists of hindlimb and pelvic elements; additional material described by Gilmore (1933a) has since proven to come from a therizinosauroid (Mader and Bradley 1989). The material from China is difficult to diagnose relative to other tyrannosaurids, and the discovery of cranial elements does not resolve this situation. Thus, in this analysis Alectrosaurus remains a problematic primitive tyrannosaurid. Material from Mongolia referred to this taxon by Perle (1977) is more complete; Currie (2000) described the presence of two to three incisiform maxillary teeth, which would constitute an autapomorphy for this taxon. However, the Bayanshiree fossils are not definitely referable to Alectrosaurus and await adequate description. Currie (2000a) estimates the total length of Alectrosaurus (and the Bayanshiree taxon, if different) to be less than 5 m. The “aublysodontine” teeth from the uppermost Cedar Mountain Formation of Utah referred to by Kirkland et al. (1997) and Cifelli et al. (1997a) as cf. Alectrosaurus have not yet been demonstrated to be morphologically more similar to that Asian taxon than to other tyrannosaurids.