This small-but-intriguing fossil comes from my display case. It is a fragment of plesiosaur limb bone that shows definitive evidence of predation by Jurassic Period sharks. Although it’s difficult to say with complete certainty, after doing a substantial amount of research (including conferring with a well-known paleontologist colleague), I believe it to be a partial radius (forelimb bone) from a genus of cryptoclidid plesiosaur known as Colymbosaurus.
There are two known species, with both reaching some five meters in length (16+ feet) and around a ton in weight (I calculated this by doing a size comparison of the pleisosaur’s body with a leatherback sea turtle and scaling up accordingly). They were piscivores (fish eaters), and were effectively the sea lions of the Jurassic.
The partial radius’s LOA is 4.75 inches. If you look closely at the images below, you can see the rake marks as a Jurassic shark (judging by the marks and bite size, probably a Hybodus) tore away at the carcass. It’s impossible to tell if the plesiosaur was already wounded – perhaps from an attack by a pliosaur of some kind – and a horde of sharks took advantage, came in and tore it apart, or if it was simply scavenged after its death. Either way, it’s intriguing to hold a bone fragment in your hand and realize that, not only are you holding the remains of an animal that existed eons ago, but that you also know what ultimately happened to it.
Provenance is Kimmeridgian, approximately 155 million years old. The piece was dredged from Weymouth Bay, Dorset, in the United Kingdom.
Thanks for stopping by. I hope you enjoyed the piece.