Leptictidae

Leptictidae is an extinct family of small, primitive placental mammals that lived from the early Cretaceous to the Oligocene epochs. These insectivores were once thought to be closely related to modern shrews and hedgehogs, but more recent phylogenetic analyses place them as basal members of the superorder Eutheria, potentially representing an early offshoot of the placental lineage. Leptictids were characterized by their small size, long snouts, and relatively large brains. Their teeth were adapted for an insectivorous diet, with sharp cusps for crushing the exoskeletons of insects and other invertebrates.

Fossils of leptictids have been found in North America and Europe. The family includes several genera, such as Leptictis, Palaeictis, and Plethtrodon. Leptictids were generally terrestrial, though some may have been semi-arboreal or fossorial. Their evolutionary history is complex, with a significant diversification in the Paleocene and Eocene epochs. Despite their widespread distribution and ecological success for a considerable period, leptictids eventually went extinct. Their disappearance is often attributed to competition with more advanced mammalian groups that evolved later, particularly rodents and early carnivorans. The study of leptictids provides valuable insights into the early evolution of placental mammals and the diversification of mammalian faunas following the Cretaceous-Paleogene extinction event.