Morganucodonta ("Glamorgan teeth") is an extinct order of basal Mammaliaformes, a group including crown-group mammals (Mammalia) and their close relatives.

Their remains have been found in Southern Africa, Western Europe, North America, India and China.

The morganucodontans were probably insectivorous and nocturnal, though like eutriconodonts some species attained large sizes and were carnivorous.

The double jaw articulation and retention of the postdentary bones are characteristic of many of the earliest Mammaliaformes, but are absent today in mammals: All crown-group mammals have a lower jaw that is composed of a single bone, and the articular has been incorporated into the middle ear, having become the malleus (while the quadrate has become the incus).Unlike more basal therapsids such as Sinoconodon, morganucodontan teeth were diphyodont (meaning that they replaced their teeth once, having a 'milk' set and 'adult' set as seen in today's mammals including humans[3] and not polyphyodont (meaning that the teeth are constantly replaced, and the animal and its teeth get larger throughout its lifetime, as in reptiles).

At least Megazostrodon and Erythrotherium are unique among basal mammaliaforms for lacking epipubic bones, suggesting that they didn't have the same reproductive constraints.

[12] Others use crown-group terminology, which limits Mammalia to the descendants of the closest common ancestor of living mammals.