Akidolestes cifellii (Li and Luo 2006; Yixian Formation, Early Cretraceous. 124 mya; NIGPAS 139381A, B) nests as a basal toothed platypus in the large reptile tree, contra the original interpretation that considered the many similarities convergent. Akidolestes was derived from a sister to Kuehneotherium (see below) with long jaws containing many more teeth than is typical for mammals.
As a monotreme, Akidolestes was an egg-layer, yet providing nourishment for its hatchlings with an early form of milk secreting from ventral glands in its skin.
It probably was a fish and tadpole eater and had a thick, probably waterproof, furry coat.
Teeth Prior to the toothless condition found in Ornithorhynchus, phylogenetic predecessors developed more teeth. Akidolestes is one example. Keuhneotherium is yet another (see below).