Articular bone

This article is about the articular bone. For articular surface or articularation, see joint.

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 Stem-mammal. In these animals it is connected to two other lower jaw bones, the suprangular and the angular. It forms the jaw joint by articulating with the quadrate bone of the skull.

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.

Morganucodontidae had both types of jaw joint: dentary-squamosal (front) and articular-quadrate (rear).

One theory is that in mammals, the articular bone has migrated to the middle ear to become the malleus, while the quadrate bone becomes the incus. Paleontologists regard this differace as the defining characteristic of mammalian fossils.

See also

• Evolution of mammalian auditory ossicles