The Ornithorhynchidae are one of the two extant families in the order Monotremata, and contains the platypus and its extinct relatives. The other family is the Tachyglossidae, or echidnas. Within Ornithorhynchidae are two genera, Obdurodon and Ornithorhynchus:
Family Ornithorhynchidae
Genus †Obdurodon — an ancient branch of the platypus family