Although some authors have considered Nanotyrannus lancensis (Bakker et al. 1988)

synonymous with T. rex (Carr 1999; Carr and Williamson 2004; Holtz 2004; Glut 1997, 2000, 2003, 2006), others (Bakker et al. 1988; Currie 2003; Larson this volume) do not agree. Tooth count, bone shape, and foramen placement and size, along with many other skeletal differences, seem to clearly separate the 2 genera. Because there is so much evidence separating Nanotyrannus from T. rex, I have excluded Nanotyrannus from the following list of T. rex specimens.