As was clear from the abundance for paleosols, the Badlands beds overlying the Cretaceous are all terrestrial deposits. But there is a pretty substantial slice of time represented from the Chadron to the Brule, and we’ve also seen from the sediments and soils that there may have been a climate shift over that time, so differences in the faunas of these units might be expected. We’ll start by looking at the oldest unit, the Late Eocene Chadron Formation.
The Chadron includes what may be the most charismatic animals in the entire White River Group, the titanotheres, such as Megacerops robustus (top of page, from SDSM). The titanotheres were roughly rhinoceros-sized, and are in fact placed in the Order Perissodactyla with the rhinos, horses, and tapirs. Small horses and true rhinos were also present, such as Trigonias osborni (the USNM example below is from Colorado):
Abundant artiodactyls included the entelodont Archaeotherium, oreodonts such as Merycoidodon, and the camel Poebrotherium (skull from SDSM):
Carnivores included the early canid Hesperocyon gregarius (SDSM) and the sabretooth nimravid Hoplophoneus primaevus (USNM).
This is just a small sample of the diverse fauna of the Chadron. In the next post, we’ll move up the section and see if there are any changes.