Vertebrates - Mammals

Mammals are a very successful group. From Terrestrial origins they have colonised most of the habitable are of the Earth’s surface, oceans and the air. The main identifying features of mammals, such as the possession of hair, milk-producing mammary glads, and the details of their reproductive system, are rarely preserved as fossils. To palaeontologist, the most vital mammalian identification feature is the jaw articulation between the dentary bone (the only bone in the lower jaw) and the squamosal bone in the skull. The quadrate and articular bones, forming the articulation in other vertebrates, became associated with mammalian hearing, and survived today as the incus and malleus of the middle ear.