Docodonta

Docodonta is an order or suborder of extinct mammaliaforms. They lived during the mid- to late-Mesozoic era.

Docodonts Temporal range:
Reconstruction of Castorocauda. Note the fur and the adaptations for swimming (broad, flat tail; webbed feet) and for digging (robust limbs and claws).
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Clade:	Therapsida
Clade:	Cynodontia
Clade:	Mammaliaformes
Clade:	†Docodonta Kretzoi, 1946
Genera
Docodontoidea Dsungarodon Simpsonodon Docodontidae

They had sophisticated molars, from which the suborder gets its name. In the fossil record, isolated teeth and bits of jawbones are found.[1]

Docodonts are not quite as closely related to the placentals and marsupials as the monotremes are, so they are not included among the crown-group mammals.

Because of their molars and their lower jaw being a single bone (the dentary), they are generally regarded as mammals. However, those authors who limit the term "Mammalia" to the (living) crown group exclude docodonts. They use the term mammaliaformes instead.

Docodonts were primarily herbivorous or insectivorous. However, Castorocauda, adapted to a semi-aquatic life, has teeth which suggest it ate fish.

Castorocauda is important because the first find was an almost complete skeleton (a real luxury in paleontology). It breaks the "small nocturnal insectivore" stereotype.[2] It was noticeably larger than most Mesozoic mammaliaform fossils, and gives absolutely certain evidence of hair and fur. Of course, this strongly suggests mammalian-type temperature regulation.