Obdurodon is an extinct genus of platypus containing three species. Obdurodon differed from modern platypi in that it still had teeth (except for juveniles, the modern platypus does not have teeth).

Obdurodon dicksoni

Obdurodon dicksoni is known from a single skull found at Riversleigh, Australia. It lived during the Miocene.

Obdurodon insiginis

Obdurodon insignis is known from some teeth and fragments of jaw and pelvis found at the Tirari Desert, South Australia. It lived during the Middle Miocene.

Monotrematum sudamericanum

Monotrematum sudamericanum is now more often held as part of the same genus as Obdurodon. It is known only from two lower and one upper platypus teeth found at Punta Peligro, Argentina. It lived during the lower Paleocene. Monotrematum is the only known non-Australasian platypus. The main difference, apart from continent and age, is its size: the teeth of Monotrematum are around twice as large as other platypi.

According to Pascual, "The preserved enamel in the central region shows that the crown pattern is almost identical to that of Obdurodon: it is composed of two V-shaped lobes, the anterior of which is wider, separated from the posterior one by a valley that connects the lingual and buccal sides of the crown separating the anterior and posterior lobes."

These fossils presently reside in the collections of Museo de La Plata and Museo Paleontológico Egidio Feruglio, both in Argentina.

Links and references

• Archer, et al. "Description of the skull and non-vestigial dentition of a Miocene platypus (Obdurodon dicksoni) from Riversleigh, Australia, and the problem of monotreme origins".
• Augee, M.L. "Platypus and Echidnas". Royal Zoological Society of New South Wales. 1992. Pages 15-27. (O. dicksoni).
• Pascual, et al. "First discovery of monotremes in South America". Nature 356. 1992. Pages 704-706. (Monotrematum).
• Woodburne and Tedford. "The first Tertiary Monotreme from Australia." American Museum. Novitates Number 2588. 1975. Pages 1-11. (O. insignis).