New Saurolophine Material from the Upper Campanian-Lower Maastrichtian Wapiti Formation, West-Central Alberta

Abstract

A saurolophine hadrosaurid from the Upper Cretaceous Wapiti Formation of west-central Alberta is described on the basis of an incomplete skull, which was found in association with a partial postcranial skeleton. The new specimen comprises the first semi-complete cranial material of a hadrosaur from the Wapiti Formation, and includes the right prefrontal, left maxilla, both jugals, right quadratojugal, left quadrate, left dentary, and ?left angular. The skull has similarities to those of similar-sized individuals of 'Edmontosaurus'; however, the short dentary diastema in the Wapiti saurolophine is unlike that of 'Edmontosaurus'. Histological analysis indicates the individual was likely a subadult. The new skeleton comes from the Red Willow Coal Zone at the top of Unit 4 of the Wapiti Formation, placing it on or close to the Campanian-Maastrichtian boundary. A phylogenetic analysis recovers the Wapiti hadrosaur in a polytomy with other saurolophines. Although it could not be assigned to a particular genus, the new specimen underscores the potential of this formation to fill gaps in the terrestrial fossil record of southern Alberta