The Karoo Supergroup is a set of fossil-bearing rocks ranging in age from about 300 million to 179 million years old, and is best exposed in South Africa. The youngest Karoo rocks are volcanic lavas that were extruded as the southern supercontinent of Gondwana broke apart to form Africa, Antarctica, and Australia. In Malawi, south central Africa, Karoo deposits in the southern part of the country are capped by basalt dated at about 179 million years old, and in the northern part of the country sediments contain a fauna of primitive mammal relatives found at a site no more than 258 million years old. One of the fossils is the skull of a new species with strange bony growths on its head.