Albertosaurus older "Gorgosaurus libratus" (sometimes called "Albertosaurus libratus"; see below). These two species are the only described albertosaurines; other undescribed species may exist. Thomas Holtz found "Appalachiosaurus" to be an albertosaurine in 2004, but his more recent unpublished work locates it just outside Tyrannosauridae, in agreement with other authors. The other major subfamily of tyrannosaurids is the Tyrannosaurinae, which includes "Daspletosaurus", "Tarbosaurus" and "Tyrannosaurus". Compared with these robust tyrannosaurines, albertosaurines had slender builds, with proportionately smaller skulls and longer bones of the lower leg (tibia) and feet (metatarsals and phalanges). Below is the cladogram of the Tyrannosauridae based on the phylogenetic
Anomocephalus mm. The pes showed five partial digits and they were all robust with arthrodial joints between the distal metatarsals and proximal phalanges as well as between the phalanges. Additionally, 15 left and three right gastralia were preserved as long, thin, and delicate bones. "Anomocephalus" exhibits palatal teeth and the morphology of the teeth is consistent with a high-fiber herbivorous diet. Cisneros and colleagues suggested that "Anomocephalus" had an incipient propaliny during the occlusions due to the longitudinal dimensions of each facet of the quadrate being twice as large as the transversal dimension. They suggest that this would allow for forward