Raranimus

Raranimus Temporal range: Middle Permian, 270 Ma PreЄ Є O S D C P T J K Pg N ↓
Holotype snout
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Order:	Therapsida
Genus:	†Raranimus Liu et al., 2009
Type species
†Raranimus dashankouensis Liu et al., 2009

Raranimus is an extinct genus of therapsid of the Middle Permian. It was described in 2009 from a partial skull found in 1998 from the Dashankou locality of the Xidagou Formation, outcropping in the Qilian Mountains of Gansu, China. The genus is the most basal known member of the paraphyletic order Therapsida, from which the class Mammalia is a descendant taxon.

Raranimus shares a number of features with later therapsids and ancestral sphenacodontids. The skull consists of a well preserved rostrum. The teeth suggest a carnivorous lifestyle for Raranimus, as the incisors are recurved and the second canines are serrated on their posterior edges. The incisors are morphologically similar to those seen in more derived theriodonts. The presence of two linguo−labially compressed canines is a diagnostic feature of Raranimus. The presence of two functional canines is characteristic of sphenacodontids, and this condition is seen in no other therapsid other than Rananimus. However, the slender, compressed shape of these canines is a derived characteristic of therapsids, with the canines of similarly sized sphenacodontids being more massively built. The precanines are small and anteriorly serrated, similar to what is seen in the synapsids Dimetrodon and Tetraceratops.

In the palate region of the skull, the anterior process of the vomer ventrally overlies the premaxilla at the anterior margin of the choana. This overlap is also seen in dinocephalians. However, unlike any other therapsid, the choanae are short and extend only from the level of the fourth incisor back to the first canine.