RE: Platypuses may be older than we think...

[Tim Williams <twilliams_alpha@hotmail.com>]

Dann Pigdon wrote:

> It depends on exactly what *Kryoryctes cadburyi* was. I've found at least
> one phylogeny that places it within Tachyglossa:
>
> http://www.fmnh.helsinki.fi/users/haaramo/metazoa/Deuterostoma/Chordata/Syna
> psida/Basal_Mammalia/Prototheria.htm

Little _Kryoryctes_ was certainly a digger (hence the name).  But it's a 
stretch to say therefore it was a tachyglossan.  BTW, I'm not saying that's 
what you're saying, Dann; but it may be the reason behind why that website 
classifies _Kryoryctes_ as a tachyglossan (albeit with a '?').  I think there's 
a _National Geographic_ article that also alludes to it being a Cretaceous 
echidna.

However, in the paper in which _Kryoryctes cadburyi_ was originally described, 
Pridmore studiously avoided aligning _Kryoryctes_ with tachyglossids 
(echidnas).  As they put it: "On the basis of comparisons with Mesozoic and 
Cainozoic mammalian taxa in which humeral morphology is known, the Dinosaur 
Cove humerus is tentatively attributed to a monotreme.  However, several 
apparently primitive features of the bone exclude the animal concerned from the 
extant families Tachyglossidae and Ornithorhynchidae and suggest that, if it is 
a monotreme, it is a stem-group monotreme."

Cheers

Tim
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