Steropodontidae is an extinct family of early monotreme mammals known from the Cretaceous of Australia.

Taxonomy

Steropodon was initially placed in the crown group monotreme family Ornithorhynchidae but was subsequently made the type genus of Steropodontidae, its own monotypic family. The monotreme Teinolophos was suggested to also belong in this family, before also being placed in a distinct family. Parvopalus, known from the same locality as Steropodon, may be a steropodontid.

Description

Steropodontids are small monotremes; Steropodon has an estimated body mass of 2 kg, and Parvopalus represents the smallest mammal found in its faunal assemblage. Members of this clade are characterized by having narrow and tall dentaries compared to other monotremes, and a prominent ascending ramus of the dentary.