[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Coelurus a maniraptoran (for how long?)

David Marjanovic wrote-

> I'd love it!!!

Great.  Just send me your revised character list and taxon list when you get
it finished.

> I may have interpreted too much into skeletal restorations, or mixed them
> with *Scipionyx*. *Scipionyx* seems to have wrists much like *Allosaurus*,
> which should place it as a basal coelurosaur (its furcula, which would
> like in allosaurids if fused, may confirm this). (Coelophysoids are really
> too far away for an analogy, my error.) From the illustrations that I have
> it seems like there was no big semilunate carpal in compsognathids,

I think Scipionyx may have fused the two carpals together to form the
semilunate, unlike Allosaurus.  Three disarticulated carpals are preserved
with Compsognathus.  They were only briefly described, though I don't think
any are semilunate.  I'd still like to wait until Sinosauropteryx is
described better till I make a decision.

> Does this refer only to real pneumatic foramina or does it include
> fossae (which I have done, assuming that the real character should be the
> extent of the air-sacs...)

Only actual foramina that penetrate the central wall.  Using the character
in a sense of how far the air sacks extend seems like a bad idea, as
pneumatic air sacs can leave no trace on the bone at all.

> That of *Velociraptor* is broad and V-shaped like that of allosaurids and
> *Scipionyx*. Should be a reversal, because more basal dromaeosaurs
> (*Sinornithosaurus*, IIRC *Microraptor* and *Bambiraptor* have thicker and
> rounder ones (so does *Archaeopteryx*). Those of tyrannosaurids are thin,
> but round, which looks like reducing the boomerang shape to me, and those
> oviraptorids... all illustrations I have show thick, compact, round bones
> that are indistinguishable from Archie's furcula (aka The Unbreakable
> Wishbone ;-) ).

Sinornithosaurus and Bambiraptor stand a good chance of being closer to
birds than dromaeosaurids, but in any case Microraptor's furcula is unknown.
Because the furculae of tyrannosaurids isn't actually boomerang-shaped, the
character would be "fucula rounded ventrally" then?  I don't include
oviraptorids as having Archaeopteryx-like furculae because of their large

> :-O My error!!! This should have been at Maniraptora, and could be phrased
> as "at least 7 sacral vertebrae". *Mononykus* has 7, Ornithothoraces at
> least begin with 8; I can't find out how many *Caudipteryx*
> and *Protarchaeopteryx* have...
> *Chirostenotes*, however, has only 6, as is mentioned several times in the
> following ref. So do any coelurosaurs outside my contents of Maniraptora
> have 6
> sacrals?

Not a single complete alvarezsaurid sacrum has been described.  Mononykus is
generally credited with six sacrals (must be unpublished information), but
there's certainly no evidence for seven.  Caudipteryx has five,
Protarchaeopteryx has six or less based on ilial length.  Several taxa
outside your Maniraptora have six sacrals.  Troodontids and Rahonavis do.
Ornithomimids do, except possibly Garudimimus, but this is debatable.  In
addition, Alxasaurus, Nanshiungosaurus? bohlini and Nanshiungosaurus
brevispinus have only five sacrals.  Excluding pygostylians, only Avimimus,
Ingenia and possibly Nomingia have seven sacral vertebrae.

> As someone remarked onlist last time, this feature was noticed first as a
> difference between tyrannosaurids (that have it) and *Allosaurus* (which
> said not to have it). So I really think this is a typo in a character
> matrix.

I first saw this character mentioned by Dong and Currie (1993) in reference
to its absence in Sinraptor and presence in Allosaurus, so I don't think
it's a typo.

> *Archaeopteryx*, *Dromaeosaurus* and the braincase assigned to *Protoavis*
> lack it, but *Chirostenotes* _has_ it... oviraptorids should have it too,
> unless nerve positions werechanging all the time in coelurosaurs (and
> anywhere else, AFAIK). Another typo?
> What is the condition in *Erlikosaurus*? I don't have the famous paper...

I don't know the condition in Erlikosaurus.  The supposed absence in
oviraptorids could always be a typo- it was just a zero in a matrix after

> The *Eotyrannus* paper makes that comparison to troodontids...

Yes, I was confused when I read it, as it implies troodontids have fused
interdental plates, while I thought they were absent.  Maybe all "absent"
interdental plates are really indistinguishably fused to the jaw bone.

> Better phrasing for the character: Maniraptorans lack a transition point
> have procoelous caudals? (May be applicable only to oviraptorosaurs,
> alvarezsaurids and maybe segnosaurs...)

Alvarezsaurids have a transition point.  Distal caudals are elongate,
without transverse processes and have long prezygopophyses.  Same could be
said for Caudipteryx, Nomingia, Avimimus and Yandangornis.  Neither
segnosaurs, Caudipteryx, Microvenator, caenagnathids, oviraptorids,
Yandangornis, enantiornithines or ornithurines have procoelous caudals.
Only alvarezsaurids and Patagopteryx do.

> BTW, the description of *Shuvuuia* mentions some characters that unite
> Alvarezsauridae and other birds and can only be found in the Supplementary
> information... :.-( I have yet to spend a few hours at the Nature

Well, I've included all their characters in my analysis, so whatever uniting
they're doing, it's not working. :-)

> >From the comparisons -- "It is still uncertain whether the quadrate head
> (caput quadrati) of the first birds articulated with the braincase as well
> as the squamosal and, even if it did, whether it was divided. The most
> ancient bird with an unquestionably avian, double temporo-quadrate
> articulation is *Enaliornis* [Early Cretaceous], in which the otic and
> squamosal surfaces are separated by the dorsal pneumatic recess
> and Galton, 1991). The heads of the known quadrates of *Archaeopteryx*
> (Elzanowski and Wellnhofer, 1996:fig. 3, not slightly schematized fig. 2),
> *Gobipteryx* (Elzanowski, 1974), and *Patagopteryx* (Chiappe, 1996; Sylvia
> Hope, pers. comm.) are damaged.

How very interesting.  Confuciusornis has a double-headed quadrate (Chiappe
et al., 1999).  Apparently derived hesperornithiformes reversed then (as
Enaliornis is a basal member).  I'll need to change Patagopteryx's entry to
? in my matrix.  If Gobipteryx has a damaged quadrate, someone needs to look
at Protopteryx, Eoenantiornis, the Spanish hatchling or Liaoxornis.  Perhaps
other Liaoning taxa (Cathayornis, etc.) would be useful as well.....

> Are any segnosaur tail ends known?


Mickey Mortimer