Monotrematum

Monotrematum sudamericanum is an extinct monotreme species from the Paleocene (Peligran) Salamanca Formation in Patagonia, Argentina. It is one of only two monotremes found outside Oceania.

==Taxonomy== A species described in 1992 and assigned to a new genus Monotrematum as the type. It is currently the only known species of the genus. The authors compared their fossil material to the genus Obdurodon, ornithorhynchid species first discovered at Australian fossil sites in 1975. It is considered to possibly be a stem-ornithorhynchid, although this is uncertain given that several divergence estimates have found the family to be significantly younger.