Thomomys, Heterocephalus and Ceratogaulus

Thomomys bottae (Wied-Neuwied 1839, Early Pliocene to present) is the extant pocket gopher, a fossorial rodent. They rely more on their incisors for digging than other gophers do.

Heterocephalus glaber (Rüppell 1842-5; 8-10cm) is the extant naked mole rat. It has a cold-blooded metabolism, lives underground, can move backwards as fast as forward,not the claws, but the teeth; protruding outside the lips are used for digging, is essentially hairless, lives in a colony dominated by a queen and may live up to 32 years in a low oxygen environment, or several times longer than related taxa. Here it nests alone between the Solenodon/Gomphos clade and the hedgehogs (see below).

Ceratogaulus rhinocerus (Matthew 1902; Miocene to Pliocene) is the extinct horned gopher. Here it nests with the modern pocket gopher and the naked mole 'rat'.

Hopkins SSB 2005. The evolution of fossoriality and the adaptive role of horns in the Mylagaulidae (Mammalia: Rodentia). Proceedings of the Royal Society B. 272 (1573): 1705–1713.

Matthew WD 1902. A horned rodent from the Colorado Miocene, with a revision of the Mylagauli, beavers and hares of the American Tertiary. Bull. American Museum of Natural History 16: 291–310. PDF

Rüppell E 1842-5. Säugethiere aus der Ordnung der Nager, beobachtet im nordöstlichen Africa. Museum Senckenbergianum: Abhandlungen aus dem Gebiete der beschreibenden Naturgeschichte. 3: 99–101.

Wied-Neuwied M 1839. Nova Acta Phys.-Med. Acad. Caes. Leop.-Carol 19(1):377.

wiki/Naked_mole-rat
wiki/Horned_gopher
wiki/Smooth-toothed_pocket_gopher

Basal Mammalia

Monotremata

Basal Marsupialia

Akynodonta 1