Written in the Hills
Middle Ordovician cephalopod, part 5a
Bruce Stinchcomb

One a geology field trip, Bruce L. Stinchcomb explains the occurrence of a large
Ordovician age fossil in a cut on I-55 south of St. Louis, Mo. These cephalopods
were some of the largest animals for their time. They form part of GOBE
(the great Ordovician diversification event).

Ozarks Paleontology