Other Mammals from North America

What are Other Mammals? This group includes many extinct mammals that do not belong in the other three groups. These mammals share some skeletal features with the others (placentals, marsupials, and monotremes), but they differ in other features, particularly in the teeth, jaws, and skull. Most of these mammals were small insectivores and resembled modern rodents. Included here is the oldest known mammal, Adelobasileus, as well as other early forms, like Kuehneotherium, Sinoconodon, and Morganucodon. Also included are the triconodonts, which had teeth with three cusps in a row, and the multituberculates, which had many small cusps, or tubercles, on their teeth. The fossil record of this group extends back to the Late Triassic, and the last members went extinct in the Tertiary.

First known fossil occurrence: Triassic.

Last known fossil occurrence: Tertiary.