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Extinct order of mammaliaforms

Docodonta is an order of extinct Mesozoic mammaliaforms (advanced cynodonts closely related to true crown group mammals). They were among the most common mammaliaforms of their time, persisting from the Middle Jurassic to the Early Cretaceous across the continent of Laurasia (modern day North America, Europe, and Asia). They are distinguished from other early mammaliaforms by their relatively complex molar teeth. Docodont teeth have been described as "pseudotribosphenic": a cusp on the inner half of the upper molar grinds into a basin on the front half of the lower molar, like a mortar and pestle. This is a case of convergent evolution with the tribosphenic teeth of therian mammals. There is much uncertainty for how docodont teeth developed from their simpler ancestors. Their closest relatives may have been certain Triassic "symmetrodonts", namely Woutersia, Delsatia, and Tikitherium. For much of their history of study, docodont fossils were represented by isolated teeth and jaws. The first docodont known from decent remains was Haldanodon, from the Guimarota site of Portugal. Recently, exceptionally preserved skeletons have been discovered in the Tiaojishan Formation of China. Chinese docodonts include otter like, and squirrel like species,

The oldest unambiguous fossil evidence of hair is found in a well preserved specimen of the docodont Castorocauda, though hair likely evolved much earlier in synapsids. Vertebrae at the base of the tail often have expanded transverse processes (rib pedestals), supporting powerful tail musculature.

Like other mammaliaforms, docodont teeth include peg like incisors, fang like canines, and numerous interlocking premolars and molars. Most mammaliaforms have fairly simple molars primarily suited for shearing and slicing food. Docodonts, on the other hand, have developed specialized molars with crushing surfaces. The shape of each molar is defined by a characteristic pattern of conical cusps, with sharp, concave crests connecting the center of each cusp to adjacent cusps. Docodont and shuotheriid teeth are so similar that some genera, namely Itatodon and Paritatodon, have been considered members of either group.