Steropodon galmani was a prehistoric species of monotreme, or egg-laying mammal, that lived during the middle Albian stage, in the Lower Cretaceous period. It is the earliest known relative of the Platypus. Image File history File links Steropodon. ... For other uses, see Scientific classification (disambiguation). ... For other uses, see Animal (disambiguation). ... Typical Classes See below Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates. ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the production of milk in female mammary glands and by the presence of: hair, three middle ear bones used in hearing, and a neocortex region in... Families †Kollikodontidae Ornithorhynchidae Tachyglossidae †Steropodontidae Monotremes (monos, single + trema, hole; refers to the cloaca) are mammals that lay eggs instead of giving birth to live young like marsupials (Metatheria) and placental mammals (Eutheria). ... Binomial name Steropodon galmani Archer, Flannery, Ritchie, & Molnar, 1985 Steropodon galmani was a prehistoric monotreme, or egg-laying mammal species that lived during the middle Albian stage, in the Lower Cretaceous period. ... This article does not cite any references or sources. ... Ralph E. Molnar is a paleontologist who has been Curator of Mammals at the Queensland Museum and more recently of the Museum of Northern Arizona and a research associate at the Texas natural Science Centre. ... The hierarchy of scientific classification. ... Families †Kollikodontidae Ornithorhynchidae Tachyglossidae †Steropodontidae Monotremes (monos, single + trema, hole; refers to the cloaca) are mammals that lay eggs instead of giving birth to live young like marsupials (Metatheria) and placental mammals (Eutheria). ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the production of milk in female mammary glands and by the presence of: hair, three middle ear bones used in hearing, and a neocortex region in... Albian (Fr. ... // The Cretaceous Period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic Period (i. ... For other uses, see Platypus (disambiguation). ...

Steropodon is known only from a single opalised jaw with three molars, discovered at the Griman Creek Formation, Lightning Ridge, New South Wales, Australia, by Brothers David and Alan Galman. It was a large mammal for the Mesozoic, being 40 - 50 cm long. The lower molars are 5 - 7 mm in length, with a width of 3 - 4 mm. A length of 1 - 2 mm is more typical for Mesozoic mammals. Also from Lightning Ridge is Kollikodon ritchiei. For other OPAL articles, see Opal (disambiguation). ... Human jaw front view Human jaw left view Human jaw top view The jaw is either of the two opposable structures forming, or near the entrance to, the mouth. ... Molars are the rearmost and most complicated kind of tooth in most mammals. ... Lightning Ridge is a town of approximately 2000 persons in north-western New South Wales, Australia. ... “NSW” redirects here. ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the production of milk in female mammary glands and by the presence of: hair, three middle ear bones used in hearing, and a neocortex region in... The Mesozoic Era is one of three geologic eras of the Phanerozoic eon. ... Kollikodon is an extinct species of Monotreme. ...

The molars "bear striking resemblance to the tribosphenic pattern characteristic of living therians..." (Pascual). However, there are also differences: there is no entoconid, and an absence of wear seems to suggest that the upper molars (as yet unknown) did not have a protocone. The molar design that is considered one of the most important characteristics of mammals is a three-cusped shape called a tribosphenic molar. ... The above graphic is wrong. ...

Woodburne (2003, p.212) reports that the holotype is a right mandible named AM F66763. The preserved molars are m1 - m3. Page 237 includes: "In Steropodon, the mandibular canal suggests the presence of a bill, with a bill also known in Obdurodon dicksoni and Ornithorhynchus anatinus." A holotype is one of several possible types. ... Species Obdurodon dicksoni Obdurodon insignis Monotrematum sudamericanum Obdurodon is an extinct genus of platypus containing three species. ... For other uses, see Platypus (disambiguation). ...

See also

• Fossil monotremes

Families †Kollikodontidae Ornithorhynchidae Tachyglossidae †Steropodontidae Monotremes (monos, single + trema, hole; refers to the cloaca) are mammals that lay eggs instead of giving birth to live young like marsupials (Metatheria) and placental mammals (Eutheria). ...

External links

• Australia’s Lost Kingdoms
• Lost Sea Opals An array of fossils from the Lightning Ridge location. Many animal groups are represented.

References

• Archer, M., Flannery, T.F., Ritchie, A., Molnar, R.E. (1985). "First Mesozoic mammal from Australia — an early Cretaceous monotreme". Nature 318: 363-366.