Re: Are dinosaurs really reptiles?

[David Marjanovic <david.marjanovic@gmx.at>]

That's a question of how to define the name "Reptilia", and that's a matter 
of convention, not one of discovery.

> In a phylogenetic systematics (a classification system that takes into
> account only derived - evolutionarily novel - characteristics)

Wait, wait. There is not "a systematics" -- systematics is how to make 
classifications and/or how to put species into an existing classification. 
Phylogenetic systematics is a little-used synonym of cladistics, which is a 
method of the science of phylogenetics (reconstructing the tree of life), 
not of systematics; you can use the resulting trees for making 
classifications, or not.

What you actually mean is phylogenetic _nomenclature_: only clades = 
monophyletic groups are named, and ranks do not matter for the spelling or 
synonymy of names.

http://en.wikipedia.org/wiki/Phylogenetic_nomenclature

(I must add a lot of citations to that article, among other things.)

> Most researches agree that Reptilia is a group that include
> crocodiles, turtles, lizzards, snakes, tuataras their most recent
> common ancestor and all its descendants.

This definition is used by very few people, actually. Most either continue 
to use it for all amniotes that aren't birds or mammals (thus not using 
phylogenetic nomenclature), or don't use the term at all. (I've also seen 
geneticists use it for Lepidosauria, though probably just because they 
didn't care about what they were saying.)

> (Robert T Bakker once argued to elect a class to dinosaurs - including
> birds - but he was not using the phylogenetic way of thought.)

Not so much "thought" as "nomenclature".