Re: Waders and fishers

["Tim Williams" <twilliams_alpha@hotmail.com>]

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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