Metaforilla

Metaforilla is a genus of small, primitive mammals that lived during the Paleocene epoch, approximately 66 to 56 million years ago. The genus is known from a single species, Metaforilla pattersoni, which was discovered in the Willwood Formation of Wyoming, USA. Metaforilla is notable for its small size, with adults estimated to have weighed around 10 grams, making it one of the smallest known mammals.

The fossil record of Metaforilla consists of a partial skull and some postcranial elements. The skull is characterized by its small size and the presence of a single pair of upper incisors, which is a feature shared with some other early mammals. The postcranial skeleton is also relatively small and lacks many of the specialized features seen in later mammals.

Metaforilla is considered to be a basal member of the order Eutheria, which includes all modern mammals. Its small size and primitive features suggest that it may have been an early diverging lineage within the group. The discovery of Metaforilla has provided valuable insights into the early evolution of mammals and the transition from small, insectivorous ancestors to the diverse array of modern mammals.