Planirostris

Planirostris is a genus of extinct mammals that lived during the Paleocene epoch, approximately 66 to 56 million years ago. The name "planirostris" derives from Latin, meaning "flat snout," referring to a characteristic feature of the skull. These small, shrew-like creatures are known from fossilized remains found in North America.

The diet of planirostris is believed to have consisted primarily of insects and other invertebrates, a common feeding strategy for mammals of this size and era. Their dentition, though not extensively preserved, suggests adaptations for crushing small prey. Planirostris likely inhabited forest floor environments, foraging for food amongst leaf litter and undergrowth.

The evolutionary relationships of planirostris are still a subject of ongoing research. However, it is generally classified within the order Zalambdalestidae, a group of early placental mammals. These early mammals diversified rapidly following the extinction of the non-avian dinosaurs, with many new forms emerging to fill ecological niches. The discovery of planirostris fossils contributes to our understanding of this crucial period of mammalian evolution. Its presence indicates a complex ecosystem with a variety of small mammal species occupying different roles.