Docodonts

Docodonts are an extinct order of mammaliaforms, a group that includes modern mammals and their closest extinct relatives. They lived during the Jurassic and Cretaceous periods, approximately 200 to 66 million years ago. Docodonts were a diverse group, with fossils found on several continents, indicating a widespread distribution.

Their most distinctive feature is their teeth, which are often molar-like with multiple cusps arranged in a row or two parallel rows. This dental arrangement is unlike that of any living mammal, though it shares some similarities with the molars of monotremes, such as echidnas and platypuses. The name "docodont" itself comes from the Greek words "dokos" meaning "tooth" and "odous" meaning "tooth," referring to this unique dental morphology.

Docodonts varied in size, with some being as small as mice and others reaching the size of badgers. Their skeletal anatomy suggests that many were likely terrestrial, but some may have been semi-aquatic or arboreal. Fossil evidence indicates that they possessed fur, and their diet likely consisted of insects, small invertebrates, and possibly plant matter.

The exact phylogenetic position of docodonts within mammaliaforms is still debated, but they are generally considered to be either a basal lineage within the Mammalia or a closely related sister group. Their extinction likely occurred at the end of the Cretaceous period, coinciding with the mass extinction event that wiped out the non-avian dinosaurs. Docodonts represent an important branch in the evolutionary history of mammals, showcasing early diversification within the mammaliaform lineage.