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Re: Waders and fishers



Dann Pigdon <dannj@alphalink.com.au> wrote:

> Tim Williams wrote:
> AFAIK, that's around the time that the first putative aquatic > mammals appear (_Kollikodon_, _Steropodon_).


There's little evidence that these forms were aquatic. We've only got
two living monotreme types for comparison, but I doubt all monotremes
were platypus/echidna clones in the past.

I was not claiming that all extinct monotremes were aquatic simply because one modern representative (the platypus) is aquatic. Nor were _Steropodon_ and _Kollikodon_ platypus "clones". Nevertheless, the original descriptions provide evidence favoring aquatic feeding for both these monotremes. From the Australian Museum website:


"The Cretaceous monotremes were probably similar in size and shape to the modern platypus, although in modern monotremes the well-developed teeth of the fossil forms are absent. _Steropodon galmani_ may have used electroreceptors in its snout to hunt crustaceans in a similar manner to the modern platypus. The recently discovered _Kollikodon ritchiei_ has unusual dome-like teeth, which earned it the nickname 'hotcrossbunodon'. These blunt, rounded molars may have been used to crush the hard shells of mussels and other shellfish."



Tim

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