Morganucodon is a mammal-like genus which lived during the Upper Triassic in (at least) Wales, England, east Asia, and perhaps South Africa. It first appeared about 205 million years ago. The species is named Morganucodon oelheri.

It is unclear where Morganucodon should be classified. Sometimes it has been classified as a member of Eucynodonts (a mammal-like reptile group), and sometimes it has been classified as a primitive mammal in the subclass of Prototheria, order Docodonta (extinct) or Triconodonta.

What makes Morganucodon special is that some of its upper jaw resembles that of reptiles. That is, its incisors are not placed in the premaxillaries as in mammals, but rather in the maxillaries as in some specialized Therapsida, and its ear bones remain attached to the jaw. The lower jaw has only reptile elements. More research is needed to find out more about this species.

The name is often stated to mean "Morgan's tooth", but that would be Morganodon in Greek. Rather, it probably comes from a Latinization of Morgannwg, the Welsh name for Glamorgan, the county where it was discovered by Walter Georg Kühne, so it means "Glamorgan tooth". Mesozoic mammals

Morganucodon