Named By: Archer, Flannery, Ritchie, & Molnar - 1985.
Classification: Chordata, Mammalia, Monotremata, Platypoda, Steropodontidae.
Species: S. glamani (type).
Size: Estimated between 40-50 centimetres long.
Known locations: Australia, New South Wales, Lightning Ridge - Griman Creek Formation.
Time period: Mid Albian of the Cretaceous.
Fossil representation: Single opalised right mandible with 3 molar teeth.
the description of Teinolophos
in 1999, Steropodon was considered
to be the earliest ancestor of the platypus. Comparison to mammals
like the platypus has yielded body estimates of around forty to fifty
centimetres long, something that would make Steropodon
one of the
larger known mammals of the early Cretaceous period. If Steropodon
lived like a modern day platypus then it likely hunted in water like
them too. Also by staying close to water, Steropodon
may have been
able to avoid the large theropod dinosaurs like Australovenator
were in Australia at this time. The bad news however is that by
living in around water it may have come into contact with Cretaceous
era crocodiles like Isisfordia.
As often happens with Australian fossils, the jaw bone of Steropodon has been turned to opal. Another monotreme mammal that is also named from the same location and from only an opalised jaw is Kollikodon. This process of opalisation has also happened to fossils of the dinosaurs Kakuru, Rapator and Walgettosuchus.