Obdurodon
Encyclopedia
Obdurodon is an extinct monotreme
genus
containing three species. Obdurodon differed from modern platypus
es in that it had molar teeth (in the modern platypus, individuals lose their teeth upon reaching adulthood).
O. dicksoni has (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 weren't well-anchored.
Monotreme
Monotremes are mammals that lay eggs instead of giving birth to live young like marsupials and placental mammals...
genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
containing three species. Obdurodon differed from modern platypus
Platypus
The platypus is a semi-aquatic mammal endemic to eastern Australia, including Tasmania. Together with the four species of echidna, it is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young...
es in that it had molar teeth (in the modern platypus, individuals lose their teeth upon reaching adulthood).
Obdurodon dicksoni
- Discovered in 1984 by Michael Archer, F. A. Jenkins, S. J. Hand, P. Murray, and H. Godthelp, at RiversleighRiversleighRiversleigh, in North West Queensland, is Australia's most famous fossil site. The 100 km² area has fossil remains of ancient mammals, birds and reptiles of Oligocene and Miocene age...
in North West Queensland. - Habitat : Queensland
- Epoch : Lower and middle MioceneMioceneThe Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
- This species is characterized by a skullSkullThe skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
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 BrisbaneBrisbaneBrisbane is the capital and most populous city in the Australian state of Queensland and the third most populous city in Australia. Brisbane's metropolitan area has a population of over 2 million, and the South East Queensland urban conurbation, centred around Brisbane, encompasses a population of...
.
- Obdurodon dicksoni is bigger than a 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 processCoronoid processThe Coronoid process can refer to:* The coronoid process of the mandible, part of the ramus mandibulae of the mandible...
and angulary process of O. dicksoni have quite disappeared in the Platypus, leaving the Platypus's skull flat on the sides. This indicates that the mastication technique of O. dicksoni was different from that of the Platypus, using the muscles anchored to these processes. - Obdurodon dicksonis 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.
- O. dicksoni has molarMolar (tooth)Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
s, whereas the Platypus uses keratinized pads (only young Platypuses have teeth). - It seems, due to the shape of the beak, that O. dicksoni nourished itself digging in the sides of rivers whereas the Platypus digs in the bottom of the river.
O. dicksoni has (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 weren't well-anchored.
Obdurodon insignis
- Discovered in 1975 by Mike O. Woodburne and Dick H. Tedford at Etudunna Formation in the desert of Tirari.
- Habitat : South AustraliaSouth AustraliaSouth Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
- Epoch : Upper OligoceneOligoceneThe Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
- The holotype is an inferior left molarMolar (tooth)Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
and is kept in the South Australia's Museum, AdelaideAdelaideAdelaide is the capital city of South Australia and the fifth-largest city in Australia. Adelaide has an estimated population of more than 1.2 million...
. The tooth 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 its ancestor Steropodon galmani. Its beak must have been proportionally smaller than the one of Obdurodon dicksoni.
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, ArgentinaArgentinaArgentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. - Habitat : PatagoniaPatagoniaPatagonia is a region located in Argentina and Chile, integrating the southernmost section of the Andes mountains to the southwest towards the Pacific ocean and from the east of the cordillera to the valleys it follows south through Colorado River towards Carmen de Patagones in the Atlantic Ocean...
- Epoch : Lower PaleocenePaleoceneThe Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
(61 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 platypusPlatypusThe platypus is a semi-aquatic mammal endemic to eastern Australia, including Tasmania. Together with the four species of echidna, it is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young...
teeth. It is the only known non-Australasian ornithorhynchid. The main difference, apart from continent and age, is its size: the teeth of Monotrematum are around twice as large as other similar species. 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."