| 词条 | Obdurodon |
| 释义 |
| name = Obdurodon | fossil_range = Late Oligocene-Late Miocene ~{{Fossil range|28|5}} | image = Obdurodon dicksoni.JPG | image_caption = Obdurodon dicksoni | taxon = Obdurodon | subdivision_ranks = Species | subdivision =
}}Obdurodon is an extinct monotreme genus containing three species. It is sometimes referred as the Riversleigh platypus, after the location of its discovery at Riversleigh. Individuals of Obdurodon differed from modern platypuses in that adult individuals retained their molar teeth (in the modern platypus, individuals lose all of their teeth upon reaching adulthood). Compared to the modern platypus, which is a mostly benthic forager, Obdurodon foraged pelagically.[1] SpeciesObdurodon dicksoniObdurodon dicksoni was described in 1992 by Michael Archer, F. A. Jenkins, S. J. Hand, P. Murray, and H. Godthelp on the basis of QM F20564, a skull and several scattered teeth found in lower-middle Miocene deposits from the Riversleigh in North West Queensland. It grew profoundly larger than the modern platypus. The septomaxilla (a part of the upper jawbone) of O. dicksoni is bigger than for the platypus, which supposes a hypertrophied beak. The coronoid and angulary processes of O. dicksoni have quite disappeared in the platypus, leaving the platypus's skull flat on the sides. This indicates the mastication technique of O. dicksoni was different from that of the platypus, using the muscles anchored to these processes. O. dicksoni's beak has an oval hole surrounded by bones in the center, whereas the platypus' beak has a V-shape and no longer surrounded by bones. O. dicksoni retained molar teeth into adulthood, whereas in the modern platypus, the adults only have keratinized pads (juveniles lose their molar teeth upon adulthood). The shape of its beak suggests that O. dicksoni sought prey by digging in the sides of rivers, whereas the modern platypus digs in the bottom of the river. O. dicksoni had (like the platypus) shearing crests instead of incisor and canine teeth. It bore two premolars and three molars on each side of the lower jaw. The M1 had six roots, the M2 had five, and the M3 only one. The upper jaw bore two premolars and two molars on each side. The M1 had six roots, the M2 four. The premolars had only one root and a very different shape from the molars. They were separated from the shearing crests by an area without dentition. The roots of the molars were barely a third as high as the crown. Molars had only been found apart from skulls, implying that they were not well-anchored.[2] Obdurodon insignisObdurodon insignis was named in 1975 by Mike O. Woodburne and Dick H. Tedford for SAM P18087, an inferior left molar found in the late Oligocene Etudunna Formation in the desert of Tirari, South Australia. The tooth has six roots. M2 with four roots and fragments of jawbone and pelvis have also been found. Obdurodon insignis had one more canine tooth (NC1) than its ancestor Steropodon galmani. Its beak must have been proportionally smaller than the one of Obdurodon dicksoni.[3]Obdurodon tharalkooschild{{Main|Obdurodon tharalkooschild}}
Notes1. ^Masakazu Asahara; Masahiro Koizumi; Thomas E. Macrini; Suzanne J. Hand; Michael Archer (2016). "Comparative cranial morphology in living and extinct platypuses: Feeding behavior, electroreception, and loss of teeth". Science Advances. 2 (10): e1601329. doi:10.1126/sciadv.1601329. 2. ^M. Archer, F. A. Jenkins, S. J. Hand, P. Murray, and H. Godthelp. 1992. Description of the skull and non-vestigial dentition of a Miocene platypus (Obdurodon dicksoni n. sp.) from Riversleigh, Australia, and the problem of monotreme origins. Platypus and Echidnas 15-27. 3. ^M. O. Woodburne and R. H. Tedford. 1975. The first Tertiary monotreme from Australia. American Museum of Novitates 2588:1-11. 4. ^1 {{cite news|title=Giant extinct toothed platypus discovered|url=http://newsroom.unsw.edu.au/news/science/giant-extinct-toothed-platypus-discovered|newspaper=UNSW Newsroom|date=5 November 2013}} 5. ^{{cite news|last=Dell'Amore|first=Christine|title=Giant Platypus Found, Shakes Up Evolutionary Tree|url=http://news.nationalgeographic.com/news/2013/11/131104-giant-platypus-evolution-science-animals-paleontology/|newspaper=National Geographic|date=November 4, 2013}} References{{Wikispecies|Obdurodon}}
External links
9 : Obdurodon|Prehistoric monotremes|Oligocene mammals of Australia|Miocene mammals of Australia|Prehistoric mammal genera|Riversleigh fauna|Oligocene first appearances|Miocene genus extinctions|Fossil taxa described in 1975 |
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