A few months ago, WSC hired Dr. Andrew McDonald as our paleontology Curator. Going forward, Andrew and I are going to split responsibility for writing Fossil Friday posts. Today is Andrew’s first post. – ACD
This is part of a jaw bone of a small crocodilian, a relative of the living crocodiles and alligators. This little crocodilian lived about 67 million years ago, near the very end of the Late Cretaceous Epoch. It swam and hunted in the swamps and streams of prehistoric Montana, alongside Tyrannosaurus, Triceratops, and other dinosaurs near the end of their reign. This fossil was discovered in a rock layer known as the Hell Creek Formation by an accomplished local fossil collector, the late Harley Garbani, and donated to WSC by his wife Mary.
This jaw bone has numerous tiny holes for the passage of blood vessels and nerves on its outer (A) and inner (B) surfaces. There are also five tooth sockets preserved (C), including three small sockets, one medium-sized socket, and one large socket, showing that the crocodilian had teeth of different sizes in its jaws when it was alive, similar to today’s crocodilians.
Valley of the Mastodon 