Linked from
The 10 pages that link to Morganucodon, each with the reason it gives.
MammalBroader topic: Its fossils preserve transitional features in teeth, jaws, and the middle ear.
MammaliaBroader topic: Its fossils preserve a transitional combination of jaw and ear features.
SynapsidBroader topic: It illustrates early mammaliaform anatomy near the transition to mammals.
SynapsidaBroader topic: Its fossils show a transitional stage in mammalian jaw and ear evolution.
CynodontiaBroader topic: It displays a transitional jaw arrangement close to the origin of mammals.