The Long, Complicated History of Appalachian Ceratopsians

North America during the Campanian

The title is a joke. Finding ceratopsian remains east of Texas is an incredibly recent phenomenon. Oh sure, there are plenty of (fragmentary) dinosaurs known from the eastern half of the United States, but those taxa tend to be tyrannosauroids, nodosaurs, ornithomimids, and hadrosaurs. I should mention at this point that, during much of the Late Cretaceous, North America was cleaved into three islands by the presence of a shallow interior sea called the Western Interior Seaway (WIS): Laramidia to the west, Nunavut to the north, and Appalachia to the east. Laramidia’s eastern north-south shoreline is where we get most of North America’s dinosaurs—Alberta, Montana, Utah, and (to a lesser extent) Texas are all hotbeds of dinosaur action, and that includes ceratopsians.

Laramidian Endemism, Part 2

Last week we saw that, during a good portion of the Late Cretaceous, North America was divided into two unequal halves by the shallow Western Interior Seaway (WIS). Those dinosaurs on western Laramidia were boxed between mountains to the west and the fluctuating coastline of the WIS to the east. They lived on a narrow, vertical strip of land running from Alaska’s North Slope to Mexico. On the other hand, everybody had beachfront property. We can’t say much about Appalachia’s Mesozoic composition, as much of its fossil-bearing rocks were destroyed by the last Ice Age. However, tyrannosaurs and hadrosaurines who were isolated prior to the formation of the WIS evolved along different lines than their western relatives. Dryptosaurus and Appalachiosaurus are the island continent’s aberrant tyrannosaurs. Hadrosaurus and a few potentially dubious genera (Lophorhothon, Hypsibema) represent the area’s hadrosaurine population. It’s ironic that, despite the area’s drastic surface area deficit, Laramidia is ridiculously rich in dinosaur fossils whereas Appalachia is not at all.

Laramidian Endemism: Part 1

Every few years, the wife and I will spend Christmas away from Alaska with her family, in Kansas. Now, the Sunflower State may not be the most exciting place to spend the holidays, but it's usually warmer than it is in Anchorage. It's also, from my point of view, a lot more geologically interesting. Now, of course, Alaska is home to about a million mountain ranges, glaciers, and volcanoes. Indeed, my state is largely a conglomeration of chunks of continental crust, earthquakes, and volcanic activity. In its own way, Alaska is the MOST interesting state, geologically speaking. But Kansas is basically made of limestone and chalk. Alaska's Mesozoic fossil record is only impressive when you look past the fact that it is made up of hundreds of bits, pieces, and chunks of bone.