Early Multituberculate Mammal Meniscoessus robustus M2 tooth

Description: This extinct genus of rodent-like mammals lived toward the end of the “age of dinosaurs”. It was a member of the extinct order Multiuberculata. The Multituberculata (multituberculates) are a major order of mammals that appeared in the middle Jurassic period, survived the C-T mass extinction, only to succumb to extinction during the Oligocene. In fact, it is the only major branch of mammals to have become completely extinct, leaving no descendants. Multituberculates derive their name from their teeth, which have many cusps or tubercles ordered in rows. Early paleontologists considered Meniscoessus teeth to be from Theropod dinosaurs. In 1929, however, Simpson published American Mesozoic Mammalia (Mem. of the Peabody Museum, 3 pt. 1; i-xv) where they were attributed to mammals. The preservation of this tooth is exquisite.

Marsh (1889), "Discovery of Cretaceous Mammalia. Part II". Am. J. of Sci. 3, 38, p.81-92.
Simpson (1929), "American Mesozoic Mammalia." Mem. Peabody Mus. Nat. Hist. iii (i), p.1-235.