paramyid

Paramyids are a group of extinct placental mammals that lived during the Paleocene and Eocene epochs. They are known from North America and Europe and are characterized by their small to medium size and primitive dental and skeletal features. Paramyids are considered to be among the earliest known placental mammals, and their fossil record provides important insights into the early evolution and diversification of this group.

The dental anatomy of paramyids is particularly noteworthy. They typically possessed a dental formula of 3.1.4.3 or 3.1.3.3, meaning they had three incisors, one canine, four premolars, and three molars in each quadrant of their jaws, or a reduced number of premolars. Their molars were often bunodont, meaning they had rounded cusps, suggesting an omnivorous diet. The incisors were typically large and procumbent, likely used for gnawing.

Skeletal remains of paramyids, though less common than teeth, reveal adaptations for arboreal or semi-arboreal lifestyles. Some species show adaptations in their limbs and feet for climbing, while others appear to have been more terrestrial. The exact phylogenetic relationships of paramyids are still debated, but they are generally placed within the group Euarchontoglires, which also includes rodents, lagomorphs, primates, and treeshrews. Their relationship to other early placental mammals is a subject of ongoing research, with various studies proposing different placements.