Re: coelurosaurs and phylogeny type stuff

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

----- Original Message -----
From: "Nick Longrich" <longrich@alumni.princeton.edu>
To: <dinosaur@usc.edu>
Sent: Thursday, September 27, 2001 10:36 PM
Subject: coelurosaurs and phylogeny type stuff


> >>  5. There's always "Ginnareemimus", the Thai ornithomimosaur without an
> >>  arctometatarsus. But I would leave ornithomimosaurs "2" until its
identity
> >>  is ascertained.
> >
> >Does it really lack the condition?
>
> ...and also, is it really ornithomimid?

So, can I ignore it until it's published? :-)

> >Then *Ornitholestes* (I counted 43 in Glut's Encyclopedia p. 644) comes
in,
> >and I have, should I use *Allosaurus* as an outgroup, a synapomorphy of
> >Coelurosauria excluding Compsognathidae. Rather uninformative as long as
I
> >have no outgroup.
>
> Horse's mouth... check out Osborn's original description of
> the animal (lamentably, as incomplete as it is, it is the best thing
> ever published on Ornitholestes).

I don't think I have a reasonable chance of getting to see an over
100-year-old paper.

> People tend to copy his figures and
> the dotted lines become solid, and people copy the copies... many of
> the bones illustrated never actually existed.

I see.

> We don't have any idea
> how many vertebrae are in the tail of Ornitholestes. One could
> probably take the same tail and draw it with anything from 30-50
> vertebrae, and if one had the artistic ability make it look good,
> plausible, even convincing.

So should I set the character at "more/less than 50 vertebrae"?

> Harass the nearest museum until they let
> you start looking at real specimens; nothing beats seeing real bone
> to understand the difficulty and ambiguity of phylogenetics.

While I, of course, wholeheartedly agree, the nearest museum -- like all
museums in Austria -- DOESN'T HAVE any real non-neornithean coelurosaur
specimens.

> On the other hand,
> some of the stuff I've seen has convinced me that other people have
> some things backwards. $*%^(*&(^, I saw *interdental plates* in
> Saurosuchus galilei, and Coelophysis-style epipophyses in a
> plateosaur. Those are not supposed to be there, so what does this
> imply... then a lot of people regard the kinked snout of
> coelophysoids as a derived character but really a subnarial gap and
> associated dentary fang is in all kinds of archosaurs, even crocs, so
> shouldn't it be primitive. Eoraptor has this too.

I see.
Do the interdental plates happen to be "small and pointed"? I don't know
what other states apart from fused and/or absent there are -- big and
pointed?

> Alvarezsaurs are jumping all over the damn
> place because they're so derived (I don't for a minute buy that
> they're ornithomimids though). Incidentally, basal alvarezsaurs are
> our friends- being less transformed they provide a sort of "missing
> link"

Sure.

> On the other hand, even if I have a character which I regard as
> phylogenetically useless, but it's easy to code (premaxillary teeth
> serrated vs. unserrated, e.g.) I throw it in.

Thanks for the idea :-)

> Regarding Avimimus- there is a bit more to them than just
> Avimimus (I'd say more but should be something on this at SVP from
> Michael Ryan). Some ?Avimimidae I've seen is hard to interpret, since
> the ankle is so heavily fused, but it may have a complete third
> metatarsal in there somewhere. Also, Russell says there's one
> Dromiceiomimus out there which apparently lacks the third metatarsal
> proximally (or is the darn thing a Dromiceiomimus then?), so I try to
> be careful about putting too much weight on its form.

This SVP meeting becomes more interesting with every day, it seems...

> incidentally- Patagonykus may not be too big to be a
> myrmecophage. Consider that aardvarks get over 100 lbs. Giant
> armadillos, sloth bears, giant anteaters, pangolins and aardwolves
> are all relatively large. In fact, the average myrmecophage is quite
> large when you consider that the majority of mammals are tiny mouse-
> and rat-sized things.

OK, but aren't its arms (and more so those of mononykines) too small
relatively?