Steropodon
Conservation status: Fossil
<tr><th bgcolor=pink>Scientific classification
<tr><td>
<tr><td>Kingdom:<td>Animalia
<tr><td>Phylum:<td>Chordata
<tr><td>Class:<td>Mammalia
<tr><td>Order:<td>Monotremata
<tr><td>Family:<td>
<tr><td>Genus:<td>Steropodon
<tr><td>Species:<td>galmani
</table>
<tr><th bgcolor=pink>Binomial name
<tr><td align="center">Steropodon galmani
</table>
Steropodon was a prehistoric monotreme, or egg-laying mammal. It lived during the middle Albian era, in the Lower Cretaceous period, and is the earliest known platypus-like creature.
Steropodon is known only from a single opalised jaw with three molars, discovered at the Griman Creek Formation, Lightning Ridge, New South Wales, Australia. It was a large mammal for the Mesozoic, being 40-50cm long. The lower molars are 5mm-7mm in length, with a width of 3mm-4mm. A length of 1mm-2mm is more typical for Mesozoic mammals.
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.
Woodburne, 2003 (p.212) reports that the holotype is a right mandible named AM F66763, which seems to work at the Australian Museum, Sydney. The preserved molars are m1-m3. Page 237 includes: "In Steropodon, the madibular canal suggests the presence of a bill, with a bill also known in Obdurodon dicksoni and Ornithorhynchus anatinus."
See also
Links and references
- Archer et al. "First Mesozoic mammal from Australia -- an early Cretaceous monotreme". Nature 318, 1985. Pages 363-366.
- BBC, Walking With Dinosaurs (http://www.bbc.co.uk/dinosaurs/fact_files/forest/birds_mammals/steropodon.shtml)
- Australia’s Lost Kingdoms (http://www.lostkingdoms.com/facts/factsheet8.htm)
- Lost Sea Opals (http://www.lostseaopals.com.au/fossils/index.asp) An array of fossils from the Lightning Ridge location. Many animal groups are represented.
