tillodontia

from The Century Dictionary.

• A remarkable group of fossil perissodactyl animals from the Middle and Lower Eocene of North America, represented by generalized or synthetic types which seem to combine some characters of ungulates, rodents, and carnivores. As an order it is represented by the family Tillodontidæ. Also Tillodonta.

from the GNU version of the Collaborative International Dictionary of English.

• noun plural (Paleon.) An extinct group of Mammalia found fossil in the Eocene formation. The species are related to the carnivores, ungulates, and rodents. Called also Tillodonta.