Cranial Growth and Variation in Edmontosaurs (Dinosauria: Hadrosauridae): Implications for Latest Cretaceous Megaherbivore Diversity in North America

In Campione and Evans's skull sample, the long, low skulls historically assigned to Anatotitan copei fall within or close to Edmontosaurus annectens variation; the authors explain these proportions through size-related allometry and individual variation, with crushing potentially accentuating skull shape.

Edmontosaurus is bounded by Campione and Evans’s cranial growth and variation sample, which supports a reduced latest-Cretaceous North American species set; the morphometric result does not assign every hadrosaurid skull or define exact genus endpoints.

Edmontosaurus is displayed at 73–66 Ma only as the stratigraphic envelope of the sampled skulls, not an independently established global genus duration. The interval is a source-bounded sample window, not a global FAD, LAD, divergence date, continuous occupancy claim or direct-ancestor assertion.