[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: More on Argentavis
Michael Habib wrote:
Granted, ostriches appear to be well above the maximum mass for a volant
bird (though not the limit for volant vertebrates as a whole, see
pterosaurs...), but many ratites are not. Am I mistaken in saying that the
evidence suggests an increase to ostrich size *after* loss of volancy,
rather than a loss of flight in the specific lineage leading to ostriches
as size reached maximum launch limits?
I had the same thought. Ratites are almost always recovered as a
monophyletic group, and the most parsimonious explanation is that
flightlessness is primitive for the clade. Given the flight abilities of
the tinamou, it may be that overall poor flight ability is primitive for
palaeognath birds. I agree that loss of volancy almost certainly occurred
prior to an increase to ostrich size.
The basal part of the neornithean tree seems especially prone to both loss
of flight and impressive increases in body size; as well as ratites, we also
have dromornithids and gastornithids (both regarded as galloanseraeans, or
at least basal neognaths). It could be some ecomorphological
pre-disposition to loss of flight + increase in body size; or it could just
be opportunistic (i.e., lots of available ecological niches at around the
same time); or just coincidence.
Local listings, incredible imagery, and driving directions - all in one