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Re: Island-dwelling dinosaurs (was Re: Gargantuavis neck vertebra)



Anthony Docimo <keenir@hotmail.com> wrote:

>  To be fair, it's easier to say "secondarily flightless" than "secondarily 
> rudimentarily".


It may be easier to say, but it may not be accurate.  If true powered
flight did not evolve until fairly late in Avialae evolution (say,
around the sapeornithid stage), then any non-flighted theropod more
basal than this stage could hardly be called secondarily flightless.


Throughout the non-ornithothoracean Paraves, there seems to have been
a great deal of experimentation in aerial locomotion going on.  Lots
of little theropods with big wings, but not much of a flight apparatus
to speak of.  The distinction between "flighted" and "flightless" was
blurred, so the term "secondarily flightless" is meaningless, and
potentially misleading.  This is different to the modern world, where
all birds (flighted or flightless) share a common ancestor (a basal
neornithean) that was capable of powered flight.


If velociraptorines evolved from ancestors that had some aerial
capabilities (which seems likely), then this does not necessarily make
taxa such as _Velociraptor_ secondarily flightless.






Cheers

Tim