Lindsay Zanno et al. report the discovery of a new tyrannosaur that helps to fill in a 70 million year gap in the fossil record. This new species reveals that the earliest North American tyrannosaurs relied on speed and small body size to survive and that apex predator status and large body sizes were not reached until much later in their evolutionary history.
- Lindsay E. Zanno
- Ryan T. Tucker
- Peter J. Makovicky
