Alectrosaurus olseni, Gilmore, 1933

Rauhut, Oliver W. M., 2003, The interrelationships and evolution of basal theropod dinosaurs, Special papers in palaeontology 69, pp. 1-213 : 44

Alectrosaurus olseni

was described as a tyrannosaur on the basis of two specimens from the Iren Dabasu Formation of Inner Mongolia, China, by Gilmore (1933). Mader and Bradley (1989) reviewed the syntype material and pointed out that one of the specimens described by Gilmore, an incomplete forelimb, represents a therizinosaur (= segnosaur in their paper), while the other one, an almost complete hindlimb (AMNH 6554), was designated as the lectotype of Alectrosaurus . Mader and Bradley (1989, p. 48) noted close similarities in hindlimb morphology with both tyrannosaurids and orn ithomimids, but referred Alectrosaurus to the former clade, based on the detailed morphology of the tubercle for the insertion of the m. iliofibularis on the fibula, the presence of a hallux, and the conservative morphology of the pedal unguals. It must be noted, however, that the latter two characters represent plesiomorphies that might have been present in more basal, non-o rn ithomimid ornithomimosaurs, such as Deinocheirus , so that the only evidence for a tyrannosaurid relationship in the lectotype of Alectrosaurus is the morphology of the muscle attachment on the fibula. However, recently discovered additional material of Alectrosaurus seems to confirm its tyrannosaurid affinities (Perle, pers. comm, in Currie and Eberth 1993, p. 138; see also Holtz 2001a); therefore, it is included in this clade here.