The tiniest fossils
The name of this mammal-like creature means ‘twin jaw’. Stereognathus used to be classified as a mammal, but some scientists think it’s reptile. This tooth is a lower jaw right molar, and is the only Jurassic or Cretaceous mammal specimen in our database.
The Purbeck Beds are particularly famous as a source of Lower Cretaceous mammals, while Watton Cliff near West Bay is one of the oldest mammal sites in the world. The challenge is that nearly all the fossils are microscopic in size – tiny teeth and other bones. They are collected by processing bulk samples of clay and reducing them down to fine residue. The fossils are then identified under a microscope.
