Ausktribosphenidae

Ausktribosphenidae is a family of extinct mammals from the Early Cretaceous of Australia. The family includes two genera, Ausktribosphenos and Bishops, each with a single species.

Taxonomy

The family Ausktribosphenidae was first described by Tom Rich and colleagues in 1997. The type genus, Ausktribosphenos, was named for its tribosphenic molars, a type of tooth structure that is characteristic of modern placental mammals and marsupials. The second genus, Bishops, was named in honor of the late Australian paleontologist Bartholomew Wallis Bishops.

Description

Ausktribosphenids were small mammals, with body lengths estimated to be less than 15 cm. They had a long snout and a robust body, similar to modern shrews. The teeth of ausktribosphenids were adapted for an insectivorous diet. The molars had a tribosphenic structure, with a high cusp (the protocone) on the lingual side and a lower cusp (the paracone) on the labial side. This arrangement allowed for efficient crushing and grinding of food.

Fossil record

Fossils of ausktribosphenids have been found in the Wonthaggi Formation in Victoria, Australia. These fossils date to the Aptian age of the Early Cretaceous, approximately 125 million years ago. The fossils include partial jaws and isolated teeth.

Evolutionary significance

The discovery of ausktribosphenids in Australia has significant implications for our understanding of mammalian evolution. The tribosphenic molars of ausktribosphenids suggest a close relationship with placental mammals and marsupials, which also have tribosphenic molars. However, the presence of these mammals in Australia, which was isolated from other continents during the Cretaceous, challenges traditional views of mammalian biogeography.

See also

• List of prehistoric mammals
• Evolution of mammals