Contact: Andrea Gibson
Caption: This is a diagram illustrating the diversification of duck-billed and horned dinosaurs during the Late Cretaceous as a result of high ocean level and mountain uplift. The geologic time scale is to the left of the diagram, with horizontal green divisions representing the Campanian (lower) and Maastrichtian (upper) time periods. Silhouettes of North America demonstrating areas covered by ocean water during each of the time periods are to the right along with triangles designating the relative size of both the Western Interior Seaway and the Laramide mountain range. Finally, the fork within the duck-billed (black) and horned (grey) dinosaur family trees show the coinciding time (yellow bar) of a major split within each group.
Credit: Lindsay Zanno
Usage Restrictions: Lindsay Zanno
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