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Re: [Re: [Re: Non-serpentine lacertids (was RE:WHAT'S GOING ON?)]]



"T. Mike Keesey" <tmk@dinosauricon.com> wrote:

> 
> > Well that's not exactly what my quibble is. I have no (more) issues >
>with calling birds dinosaur descendants. It's just that when someone > >like
Norell or Bakker, goes around saying that dinosaurs are still > >alive, just
look at the birds in your backyard, it seems a little > >rediculous. I mean by
that logic I should be able to say that > >therapsids are still alive, just
look at your pet dog/cat or yourself. > >Just because we descended from
therapsid stock doesn't mean we should > >go around calling ourselves living
cynodonts.
> 
> Actually, Therapsida and Cynodontia *have* been incorporated into
> phylogenetic taxonomy. Mammalia are cynodontian Therapsida.
> 
> see http://www.dinosauricon.com/taxa/synapsida.html
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Yes, but the point is that noone goes around *saying* that. Not like how they
do it with birds.  

---------------------------------------------------------------

> > Same with non-avian theropods. No one is going to confuse  >
>_Tyrannosaurus rex_ with a bird (yes there is homology and yes there is >
>synapomorphy, but it's still a long way off from calling _T.rex_ a     >
>bird). It's the ignoring of the names that bothers me I guess. I don't >
>really see a point to calling a bird a dinosaur regardless of the fact >
>that those are the creatures they descended from.
> 
> Ask this, then: What is the utility of a group that includes
> _Sinornithosaurus_ with _Triceratops_, but not with _Archaeopteryx_? >What
is so special about _Archaeopteryx_?

+++++++++++++++++++++++++++++++++++++++++++++++++++++

Actually I consider both _Sinornithosaurus_ and _Archaeopteryx_ to both
qualify for the term "non-avian dinosaurs"  

----------------------------------------------------


> > Yes, but no one is going around saying that humans are living >
>therapsids
> 
> Actually, yes.
+++++++++++++++++++++++++++++++++++++++++++++++++++++

Who has said that? In what context was it said in?

Yes, humans are living therapsids, but who goes around saying that when one
can simply call humans, humans? 

---------------------------------------------------

> > or that other apes make up the non-hominoid primata.
> 
> "Apes" are non-hominin Hominoidea.
> 
> > A human is a hominid. That doesn't mean that they didn't evolve from
> > other primates, it just means that hominids diverged enough to warrant
> > their own name. Same with birds. They diverged enough from dinosaurs
> > to warrant their own name. But birds are a bit different from humans.
> > Birds are different enough to warrant a class under traditional
> > Linnean terms.
> 
> Why? What is the quantifiable, repeatable, objective criterion or criteria
for meriting "Class" status? How is Insecta equivalent to Aves? How is
Coleoptera equivalent to Struthioniformes?
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

I don't know. Why has it suddenly not become OK to call birds avians, but it's
still OK not to call birds reptiles? If we are going to dump our categories in
favour of a purely cladistic view then why don't we just call ourselves
derived archaea?

As for above, traditionally creatures have always been defined up to their
class level (e.g. Humans = _Homo_ = Hominid = Primata = Mammalia). Birds
already had a class before their dinosaurian relationships were worked out.
That means that they had enough differences to warrant a huge separate
category. Differences that stayed around throughout most of dinosaur science
and have only recently been taken down because a select few theropods show a
lot of these traits. For those theropods, I can understand the use of the term
"non-avian", but for the rest I don't see a point to it. And since the nine
thousands living avialans share more in common with each other than with
"Mesozoic dinosaurs" I don't understand why we have to remove the term Aves in
favour of Dinosauria; which seems to be the case.

-------------------------------------------------------------------

> 
> > Humans only get a familial "ranking." So a human
> > can rightly be called a primate and a mammal, but birds have become so
diverse that to say that a robin is both an avialan and a dinosaur seems a bit
much.
> 
> Why? That reflects its ancestry.
> 
> > Kinda like say a robin is an avialan and a reptilian. While true, the
> > differences are so vast that it seems like extra baggage to tag >
>reptilian on UNLESS when doing phylogenetic work. 
> 
> Well, it all depends on context.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Why does calling a robin an avialan and a dinosaur Ok because it reflects
ancestry, but calling it an avialan and a reptile depends on context?

Shouldn't they both depend on context?

------------------------------------------------------------
 
> > Again it seems that everyone thinks that I want to kick Aves out of
> > dinosauria. That is not the case.
> 
> Then why say that they merit their own "Class"?

++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Because in order to warrant that "status" you must have a large amount of
differences from other groups and basic bird traits, I believe, are large
different enough from basic dinosaur traits, to warrant that (though one is
really just built off the other). When I use the term class I am not giving it
all the power that Linneas et al did. I just mean to use it as a easier way to
define a group as diverse as birds have become. It's like on your cladograms.
You have Avialae there; all I'm saying is that every creature after that
should be called avian in the majority of cases. Dinosaur classification
should only be used in the appropriate context and not thrown about as hap
hazardly as it has been.

------------------------------------------------------------------
 
> > All I'm saying is that as far as names go, I do think there should be > >a
boundary (albight a fuzzy one) that states what category the creature > > in
question falls under. Which ever category it is, that is the name > >it should
be called by. If it is one of those muddy transitionals then > >go ahead and
give it the non-avian prefix.
> > 
> > I suppose it could go something like this.
> > 
> > 1) If it meets the basic criteria to be a dinosaur, it should be > >called
a dinosaur
> > 
> > 2) If it meets the basic criteria to be a bird, it should be called a >
>bird.
> > 
> > 3) If it meets the basic criteria to become a dinosaur and meets a    >
>large part of the criteria to be a bird then call it a non-avian ----
> 
> I don't see the sense of this. "Non-avian" just means "not belonging to
> Aves", and applies equally to _Deinonychus_, _Triceratops_, myself, and
> club mosses.
> 
> Only if you were speaking in certain contexts (usually regarding flying
> ability or traditional taxonomy) would you need the term "non-avian". If
> you're speaking of integument, "non-coelurosaurian" might (*might*) be
> better. For features of modern birds, "non-neornithean". If you're
> speaking about the extinction, "Mesozoic" might be a better prefix. You
> don't have to say "non-avian" every single time.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

And *that* is what the crux of my argument is. The term "non-avian" *should*
only be used in the appropriate context, but it is increasingly not being done
that way. In more and more books, periodical, newstories & specials, the term
is being used *almost* as a replacement for the term dinosaur. And that is
what is bugging me so much.


Jura

Jurassosaurus's Reptipage: A page devoted to the study of the reptilia:

http://reptilis.webjump.com

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