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Re: Are these characters accurate?
Jason Michalak wrote-
> Thanks for the reply Mr. Mortimer. If you don't mind another, how many
> synapmorphies to birds share with dinosaurs as a whole? I think Greg S.
> said it was well over 200 and Padian and Chiappe less than 200. It seems
> like a pretty big difference between the two figures!
That depends on what exactly you mean, and even if I knew that, no one would
be able to give you a solid answer now.
If you mean "how many synapomorphies present in birds are shared by and
inherited from the most basal dinosaur?", the answer's going to be thousands
(morphologically, probably millions genetically). But it would include a
lot of synapomorphies diagnosing more inclusive clades, like Reptilia,
Vertebrata, Animalia, etc..
If you mean "how many synapomorphies in birds are shared by, inherited from,
and first developed in the most basal dinosaur?", the answer's going to be
much less (<100 morphologically?). In realistic terms, it would be even
less (<50?), because the closest outgroups to Dinosauria
(Lewisuchus/Pseudolagosuchus and Silesaurus) are incompletely known.
I've always pictured the "number of synapomorphies shared between dinosaurs
and birds" quotes as meaning "how many synapomorphies present in birds are
shared by, inherited from and first developed in at least one non-avian
dinosaur?". This would let all dinosaurian, saurischian, theropod,
coelurosaur, maniraptoran, eumaniraptoran, etc. synapomorphies count. The
number would realistically be hundreds (I'd say definitely over 200).
Not that anyone is going to be able to list those hundreds for you, because
we haven't found them all yet. Measuring new ratios, studying remains in
more detail, and newly discovered taxa changing the polarity of characters,
will all influence the number of characters.