In Baculites, a straight shelled ammonite, the constructional limits on shell shape resulting from the limited strength of nacre in tension are circumvented by a system of vaults in the phragmocone.

The continents were in a different configuration, so yes, the ocean currents were a bit different. Lots of shallow seas, too. Here's an image from Scotese's Paleomap Project to give you an idea of ...

David Peterman in the AMMLab (Ammonoid Motility Modeling Laboratory) holding a 3-D-printed reconstruction of the planispiral ammonite, Paracoroniceras lyra. David Peterman, Kathleen Ritterbush and ...

University of Utah paleontologists David Peterman and Kathleen Ritterbush know that it's one thing to use math and physics to understand how ancient marine creatures moved through the water. It's ...