Obdurodon
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{{Taxobox | color = pink | name = Obdurodon | status = Conservation status: Fossil | regnum = Animalia | phylum = Chordata | classis = Mammalia | ordo = Monotremata | familia = Ornithorhynchidae | genus = Obdurodon | subdivision_ranks = Species | subdivision =
- Obdurodon dicksoni
- Obdurodon insignis
- Monotrematum sudamericanum
}}
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).
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Species
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Obdurodon dicksoni
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Generalities
- Discovered in 1984 by Michael Archer, F. A. Jenkins, S. J. Hand, P. Murray, and H. Godthelp, at Riversleigh in New South Wales.
- Living room : New South Wales
- Epoch : Lower and middle Miocene
- This species is caracterized by a skull and several scattered teeth. Physically, it looked much like modern platypus although there are a few significant differences.
- The holotype is kept at the Queensland Museum in Brisbane.
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Most important differences between Obdurodon dicksoni and platypus
- Obdurodon dicksoni is bigger than a platypus.
- The septomaxilla (a part of the upper jawbone) of Obdurodon dicksoni is bigger than for modern platypuses, which supposes a hypertrophied beak.
- The coronoid process and angulary process of Obdurodon dicksoni have quite disappeared in the platypus, leaving the platypus's skull flat on the sides. This indicates that the mastication technique of Obdurodon dicksoni was different from that of the current platypus, using the muscles anchored to these processes.
- Odurodon dicksoni's beak has an oval hole surrounded by bones in the center whereas the platypus' beak has a V-shape and isn't stopped on top.
- Obdurodon dicksoni has molars, whereas the platypus uses keratinized pads (only young platypuses have teeth).
- It seems, due to the shape of the beak, that Obdurodon dicksoni nourished itself digging in the sides of rivers whereas the platypus digs in the bottom of the river.
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Teeth of Obdurodon dicksoni
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Obdurodon insignis
- Discovered in 1975 by Mike O. Woodburne and Dick H. Tedford at Etudunna Formation in the desert of Tirari.
- Living room : South Australia
- Epoch : Upper Oligocene
- The holotype is an inferior left molar and is kept in the South Australia's Museum, Adelaide. She has six roots. There also have been found M2 with four roots and fragments of jawbone and pelvis. Obdurodon insignis had one more canine tooth (NC1) than his ancestor Steropodon galmani. His beak must have been relatively more little than the one of Obdurodon dicksoni.
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Monotrematum sudamericanum
- Discovered in 1992 by Rosendo Pascual, Michael Archer, E. O. Juareguizar, J. L. Prado, H. Godthelp, and S. J. Hand, at Punta Peligro, Argentina.
- Living room : Patagonia
- Epoch : Lower Paleocene (21 million years)
- 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. It 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 platypuses'. These fossils presently reside in the collections of Museo de La Plata and Museo Paleontológico Egidio Feruglio, both in Argentina.
- 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."
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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).et:Obdurodon