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Re: Pteros might be dinos?!? Oh no ...



I've said it before in response to people criticizing news articles that 
referred to them as Dinos....

It would be easy to define a monophyletic "Dinosauria" that included Pterosaurs.
Of course this would basically make Ornithodira=Dinosaria

Pteros are closer to dinos than most other groups.
While on the subject, why don't we include Lagerpeton and Marasuchus?
If Herrerasaurus/Eoraptor evolved before Saurischia split with Ornithischia, we 
could easily define a Dinosaur clade that excludes them as well.

I've known of some kids think of crocodiles as being like dinosaurs, one could 
even define dinosaurs to be synonymous with archosaur.

For that matter, we could also define Ornithodira as birds..... and say flight 
arose independently at least twice in birds, at least once with feathers, and 
once with wing fingers.


It is all semantics.....
Maybe Herrarasaurus was pre -Saur/Ornithischia split, but it is still a 
dinosaur?
But for us to call Pteros Dinosaurs, they would have had to evolve after the 
Saur/Ornith split?
What sort of standard is that?
It seems more like a standard "That looks like a dinosaur to me", and not a 
phylogenetic one.
 - Yes I realize there is more to it, by using the "looks like my conception of 
a dinosaur", Lagerpeton and Marasuchus would have been included.
Even though they were different linages, back in the triassic, I'd bet a DNA 
sequence between Eoraptor vs Marasuchus would show they were more closely 
related than Eoraptor is to a modern bird.
Its sort of like calling your family royalty of hereditary descent, and saying 
you are royalty because came from royalty: going way way way back to your 
great, great, great.... great Grandfather.
They you say this Great....Great grandfathers brother wasn't royalty as well, 
even though they both had the same parents, and this royalty thing is supposed 
to be inherited......

At the time, these groups were very closely related, just as early Synapsids 
and Diapsids were very close, and are now quite diverged.

Maybe doing cluster analysis on the tree nodes (sort of like molecular biology 
does cluster analysis on protein interaction networks), you can come up with an 
objective phylogenetic definition for which node to set the 
dinosaur/non-dinosaur division.

I think we just like being able to call people ignorant when they call a ptero 
a dino.
We will still have Plesiosaurs, I don't see those being classified as Dinos any 
time soon, and Mosasaurs definitely wont.


--- On Tue, 11/10/09, Augusto Haro <augustoharo@gmail.com> wrote:

> From: Augusto Haro <augustoharo@gmail.com>
> Subject: Re: Pteros might be dinos?!? Oh no ...
> To: mickey_mortimer111@msn.com
> Cc: dinosaur@usc.edu
> Date: Tuesday, November 10, 2009, 5:12 AM
> To assess how much "crazy" is to
> think pterosaurs are saurischian or
> theropod dinosaurs one should perform a phylogenetic
> analysis with a
> relatively large matrix as that of Brusatte et al. (2008;
> including
> more dinosauriforms and characters relative to their
> interrelationships will be useful also) under the
> constraint of
> considering pterosaurs as related to saurischians, and then
> see how
> many more steps has this tree compared with the most
> parsimonious tree
> without the constraint.
> 
> Regarding the elongation of penultimate manual phalanges,
> one should
> have care because that elongation also happens in
> Heterodontosaurus
> (Santa Luca, 1980, fig. 13), which is considered by now one
> of the
> most basal ornithischians (Butler et al., 2007). It may be
> a basal
> dinosaur feature. Thin-walled bones are also known in
> basal
> sauropodomorphs as material referred to Thecodontosaurus
> (Benton et
> al., 2000, fig. 16h).
> 
> References:
> 
> Benton, M. J., Juul, L., Storrs, G. W. y Galton, P. M.
> 2000. Anatomy
> and systematics of the prosauropod dinosaur
> Thecodontosaurus antiquus
> from the Upper Triassic of southwest England. Journal of
> Vertebrate
> Paleontology, 20 (1): 77-10.
> 
> Butler, R. J., Smith, R. M. H. y Norman, D. B. 2007. A
> primitive
> ornithischian dinosaur from the Late Triassic of South
> Africa, and the
> early evolution and diversification of Ornithischia.
> Proceedings of
> the Royal Society of London (B), 274: 2041-2046.
> 
> Santa Luca, A. P. 1980. The postcranial skeleton of
> Heterodontosaurus
> tucki (Reptilia, Ornithischia) from the Stormberg of South
> Africa.
> Annals of the South African Museum, 79 (7): 159-211.
>