At least two of the three species of prototherians are threatened with extinction or were at some point in the recent past. Long-nosed echidnas are currently listed as endangered by the International Union for the Conservation of Nature (IUCN) redlist (www.redlist.org). Habitat destruction and heavy hunting pressure have severely limited populations of this species. In the past, platypuses were declining rapidly due to their overexploitation in the fur trade, but recent conservation efforts have helped populations rebound considerably.
- Groombridge, B. 1994. 1994 IUCN Red List of Threatened Animals. Gland, Switzerland: IUCN. Accessed September 02, 2005 at www.redlist.org.