Cimolestes

Cimolestes is an extinct genus of carnivorous mammal that lived during the Late Cretaceous epoch. Fossils of Cimolestes have been found in North America, primarily in the Hell Creek Formation of Montana and Wyoming. The name Cimolestes means "chalk robber" in Greek, referring to the chalky deposits where its fossils were first discovered.

Cimolestes was a relatively small mammal, roughly the size of a weasel or a ferret. It possessed a long, slender body, a pointed snout, and sharp teeth adapted for tearing flesh. Its dentition, particularly the prominent canines and shearing carnassials, suggests it was a predator that likely fed on small vertebrates such as lizards, early mammals, and possibly insects. While its exact lifestyle is debated, it is generally thought to have been a terrestrial or semi-arboreal animal.

The discovery of Cimolestes provides valuable insights into the diversity and ecological roles of mammals during the age of dinosaurs. It represents one of the more specialized carnivorous mammals of its time, occupying a niche that was not dominated by larger predators. Its relationship to other mammals is not fully resolved, but it is often placed within the order Cimolesta, a group of extinct placental mammals.