Sphenodiscus lenticularis, Fox Hills Formation, South Dakota. Late Cretaceous (~ 70 mya). Both sides of this handsome specimen display the extraordinarily intricate suture patterns that are characteristic of this species. Also evident is part of the beautifully iridescent nacreous layer. A laterally flattened ammonite, this animal is thought to have been a relatively fast swimmer.
8 Facts That Show You're Part Fish, Reptile and Primate!
The skeleton of every vertebrate walking the Earth today has the fundamental pattern of one bone, two bones, little bones and fingers. See more facts that show you’re like Fish, Reptiles and Primates. #InnerFishPBS