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RE: Purple Paleo Prose Down Under



Tim Williams wrote:

> The 'Demon Duck of Doom' label also appears to be a reference to the 
> putative anseriform affinities of dromornithids.   I suspect that it's
also 
> a way of emphasizing that dromornithids are NOT ratites, despite the
fact 
> that they were large terrestrial flightless birds.  However, modern 
> Anseriformes contain more than just ducks, geese, and swans - this
"order" 
> also includes the screamers, which are less familiar to most people.
Those 
> researchers that put dromornithids in the Anseriformes also regard the

> screamers (Anhimidae) as being closest (both phylogenetically and 
> ecologically) to dromornithids.  Screamers are found only in South
America; 
> but I have also been told that there is evidence that the modern 
> magpie-goose (_Anseranas_) of Australia may be more closely related to
the 
> screamers than to the Anatidae (ducks, geese, swans).

    To clarify: In the DNA-DNA hybridisation studies of Sibley et al.
that where conducted in the 1980s, _Anseranas_ appeared closer to
screamers than other Anatidae s.l. DNA-DNA hybridisation is intended to
measure the overall similarity of the DNA from different taxa, and is a
fairly rough and ready method of looking at relationships (being
essentially a phenetic distance method). It's cheap, it can give you an
idea of promising directions to look in, but it's probably not very
reliable in the long run*. In all the studies I've seen more recently
(both morphological and better molecular methods), _Anseranas_ has
returned to its position as next basalmost living anseriform after
screamers. Still, _Anseranas_ is a lot more reminiscent of a screamer
ecologically than any other Anatidae s.l.
    In relation to dromornithids, analogy with other living anseriforms/
Galloanserae would suggest a largely omnivorous diet - primarily
vegetable matter, but a reasonable amount of animal food where
available.

    Cheers,

        Christopher Taylor

*My comments on the unreliability of DNA-DNA hybridisation are in no way
a condemnation of Sibley et al. for using them. Molecular methods of
looking at relationships were still in a very primitive state, and
hybridisation was probably just as good as any other technique available
at the time.

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