In the last post we looked at the sediments, paleosols, and some of the structures in the Badlands. But while the park is famous for its scenery, it is also one of the world’s great vertebrate fossil localities. While we didn’t see any in-place fossils in the park, the excellent Museum of Geology at the South Dakota School of Mines (SDSM) has numerous South Dakota fossils on exhibit, including Badlands specimens; all the specimens in this post are from their exhibits.
I had originally planned to talk about all the Badlands fossils in a single post, but the area is far too rich. So I’ve decided to break it up into several posts, starting with the oldest deposits in the park, the Cretaceous Pierre and Fox Hills Formations. Since these units are Cretaceous and marine, that means ammonites! Both units have diverse ammonite faunas, as shown below (although these particular specimens were not found within the park):
This is just a tiny sample of the ammonites found in these units (many others are on exhibit at SDSM), and of course there are other invertebrates. But what the Pierre Shale is particularly famous for are its marine reptiles, including mosasaurs such as Mosasaurus conodon (top of page) and elasmosaurs such as Styxosaurus snowii (below):
In the next post we’ll look at fossils from the Chadron Formation.