Stegomastodon

Stegomastodon ('roof breast tooth') is an extinct genus of gomphotheres. It ranged throughout North America from the Pliocene (early Blancan ~4 Ma), to the Early Pleistocene (early Irvingtonian, ~1.2 Ma). The former South American species have been synonymized with Notiomastodon platensis. The neologism 'cornady' () has been proposed in some literature as an english name for the members of this genus.

== Description == thumb|Skeleton of Stegomastodon compared with a human|leftStegomastodon mirificus is known from NMNH 10707, a roughly 30-year-old male, of which most of the skeleton has been found. Alive, it stood about tall, with a weight around . Unlike more primitive gomphotheres like Gomphotherium, it lacked lower tusks and had a shortened lower jaw. The upper tusks curved upward and were about long, and lacked enamel bands. The tall head and robust lower jaw suggest a strong vertical bite. Stegomastodon's third molars molars had at least 5 lophs (ridge-like structures), greater than previous gomphotheres. The strong bite and increased tooth complexity are suggested to be adaptations to a grazing diet.