Articular bone

The articular bone is part of the lower jaw of most vertebrates, including most jawed fish, amphibians, birds and various kinds of reptiles, as well as ancestral mammals.

[2] In most tetrapods, the articular bone forms the lower portion of the jaw joint.

[3] In mammals, the articular bone evolves to form the malleus, one of the mammalian ossicles of the middle ear.

This is an apomorphy of the mammalian clade,[4] and is used to determine the fossil transition to mammals.

[5] It is analogous to, but not homologous to the articular process of the lower jaw.

Mammalian and non-mammalian jaws. In the mammal configuration, the quadrate and articular bones are much smaller and form part of the middle ear. Note that in mammals the lower jaw consists of only the dentary bone.