For more than a century, paleontologists have been collecting abundant, often spectacular dinosaur fossils from the Western Interior of North America, with the bulk of these remains found in rocks dating to the final stages of the Cretaceous Period. Only recently have we learned that most of these dinosaurs—among them horned, duck-billed, dome-headed, and armored plant-eaters, as well as giant tyrannosaur meat-eaters and smaller “raptor-like” predators—existed on a “lost continent,” today referred to as “Laramidia."
About 96 million years ago, exceptionally high sea levels flooded central North America, resulting in a north-south oriented seaway extending from the Arctic Ocean to the Gulf of Mexico. This shallow sea isolated life-forms on the eastern and western landmasses for most the next 26 million years.
We know little of what happened on the eastern landmass, but its western counterpart, Laramidia, witnessed a tremendous florescence of dinosaurs and other Cretaceous life-forms. Surprisingly, despite the small size of Laramidia (less than one-quarter the size of present day North America) and giant sizes of many of the dinosaurs, different species co-existed in the northern and southern regions, at least during certain intervals. How were so many giant animals able to co-exist on such a diminutive landmass? Why were most of these dinosaurs adorned with bizarre bony features such as horns, crests, domes, or spikes? What lessons do these ancient fossils have for humans living on a warming planet?