A new family of bird-like dinosaurs linking Laurasia and Gondwanaland

A new family of theropod dinosaurs is described based on metatarsi from North America and Argentina. Because birds are theropod descendants, there are often problems in assigning isolated metatarsi to the proper group. Differences between the metatarsi of ground birds and theropods are detailed. In particular, it is shown that the length/width ratio of articulated metatarsi cannot be used to distinguish higher taxa. This new family represents the first occurrence of the same genus of theropod dinosaur from both Laurasia and Gondwanaland at the end of the Cretaceous, a time when the two supercontinents were supposedly still separate.