Late Jurassic (Tithonian)

Morrison Formation

Bone Cabin Quarry, Albany County, Wyoming, USA

Ultra-rare 2mm mammal tooth.

Mammal, Multituberculate.

This animal and its relatives have been referred to as “rodents” but true rodents didn’t appear until the Late Paleocene.  Ctenacodon was a genus of the Order Multituberculata, a branch of mammals entirely separate from any that live today.  They would have resembled rodents and probably had much the same lifestyle but they had a different ancestry and anatomy as exemplified in their dentition.

Ctenacodon is one of the earlier genera of the group.  It lived over 80 million years before the multituberculates (Mesodma, Meniscoessus) found in the Latest Cretaceous Hell Creek Formation.