A juvenile metatarsal of cf. daspletosaurus torosus: Implications for ontogeny in tyrannosaurid theropods

Abstract

A well preserved, but isolated metatarsal III of a tyrannosaurid dinosaur, originating probably from the Di-nosaur Park Formation of Alberta, Canada, is tentatively referred to Daspletosaurus torosus. The size of the specimen suggests that it likely comes from a large juvenile, since the width of the distal end is about 63 % of that of a much larger individual. The morphology of the specimen supports the recently suggested hypotheses that apomorphies of tyrannosaurid taxa may have developed at young growth stages, and that juveniles of albertosaurines and tyranno-saurines may be easier to distinguish from one another than previously thought. Additionally, the specimen reported here is important in that it provides an addition to the very poor juvenile fossil record of Daspletosaurus.