[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Coelurus a maniraptoran (for how long?)
HP Mickey Mortimer wrote some days ago:
> How would you like it if I made your list into a matrix and ran it on
I'd love it!!!
> > distal carpal 1 + 2 enlarged and semilunate (compsognathids have small
> carpals and
> > relatively immobile wrists like coelophysoids)
> I'm not so sure about compsognathids having coelophysoid-like carpals.
> After all, only three disarticulated elements may be referred to
> Compsognathus' carpus, while Sinosauropteryx is undescribed.
I may have interpreted too much into skeletal restorations, or mixed them up
with *Scipionyx*. *Scipionyx* seems to have wrists much like *Allosaurus*,
which should place it as a basal coelurosaur (its furcula, which would look
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, however.
> This should really be phrased better, probably as a ratio of forelimb to
> hindlimb length.
> This also needs a ratio (metacarpal I x% as long as metacarpal II)
> Again, you need a ratio (percent compared to femoral length, presacral
> length, etc.).
> Ratios, ratios, ratios.... :-) Characters must be specific.
You've convinced me :-) I'll try. May take a month, though, because
doesn't end before June 29, and some exams may be later.
> > This node might collapse into Eumaniraptora because the following
> > character
> > states are AFAIK unknown for ornitholestids and coelurids:
> > - nearly all cervical and dorsal vertebrae (at least) pneumatised (to an
> > extent often comparable to very large carcharodontosaurids and
> > sauropods)
> In both Coelurus and Ornitholestes, all cervicals and the first two
> were pneumatic. This is similar to ornithomimids and troodontids.
Does this refer only to real pneumatic foramina or does it include pneumatic
fossae (which I have done, assuming that the real character should be the
extent of the air-sacs...)
> > furcula boomerang-shaped.
> Not all of your eumaniraptoran taxa have this character. The furculae of
> Velociraptor, tyrannosaurids and oviraptorids at least are very similar to
> those of Allosaurus and Scipionyx.
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 of
oviraptorids... all illustrations I have show thick, compact, round bones
that are indistinguishable from Archie's furcula (aka The Unbreakable
Wishbone ;-) ).
> > probably wing and tail feathers (if not earlier).
> This is a good character- just can't be scored for many taxa.....
It is definitely useless to put this into a character matrix. I added it a
posteriori, just to give this important feature a place. Maybe I should have
> > -+- Maniraptoriformes: more than 5 sacral vertebrae (is that right for
> > tyrannosauroids?)
> Nope. Tyrannosaurids have five sacrals.
:-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
Hans-Dieter Sues. On *Chirostenotes*, a Late Cretaceous oviraptorosaur
(Dinosauria: Theropoda) from western North America, JVP 17(4):698-716
> > separate exit for the cranial nerve V1.
> Remember, Allosaurus has this too. And oviraptorids lack it.
As someone remarked onlist last time, this feature was noticed first as a
difference between tyrannosaurids (that have it) and *Allosaurus* (which was
said not to have it). So I really think this is a typo in a character
*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 hardly
anywhere else, AFAIK). Another typo?
What is the condition in *Erlikosaurus*? I don't have the famous paper...
> > I have forgotten whether the character "articulars and quadrates
> > pneumatised" isapplicable... that's in the archives, however. :-]
> Confuciusornis lacks a pneumatic quadrate, despite the fact it is a
> maniraptoriform in your phylogeny. Caenagnathids, Avimimus and
> enantiornithines lack pneumatic articulars.
OK. So it's not applicable, unless we infer that an air-sac was present in
the mentioned taxa and didn't invade the bone... untestable. :-(
> > -+- Arctometatarsalia:
> > It may tell something, however, that ornithomimosaurs and tyrannosaurs
> > at least have so similar proportions (stunning illustration in PDW), and
> > that troodontids and tyrannosaurs have small, pointed interdental
> > plates.
> Troodontids lack interdental plates (or else they are fused
> indistinguishably to the dentary), unlike the primitively unfused plates
> of tyrannosaurids. Then again, Eotyrannus has fused interdental
The *Eotyrannus* paper makes that comparison to troodontids...
> > -+- Maniraptora: even shorter tail, tail not stiffened distally,
> > pneumatisation extending to mid-caudals, ornithoid eggshell, maybe a
> > double-headed quadrate (though the heads can fuse...), maybe some sort
> > of proto-pygostyle (but the vertebrae are not always fused...).
> How short of tail?
Hindlimb-length or less, probably. Ratio, I know... :-)
> Alvarezsaurids have distally stiffened tails.
Better phrasing for the character: Maniraptorans lack a transition point and
have procoelous caudals? (May be applicable only to oviraptorosaurs,
alvarezsaurids and maybe segnosaurs...)
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 website...
> Caudipteryx and Microvenator lack pneumatized caudals, as do segnosaurs
> and any Mesozoic bird I've read about.
*Patagonykus* has pneumatic fossae on a caudal. Caudal pneumatization in
pygostylians is rare, maybe because of the general reduction of the tail...
> Caudipteryx may have a single-headed
> quadrate (although Jaime disagrees), as do Erlikosaurus and Avimimus.
And lots of basal ornithothoracines, according to Chatterjee's
Palaeontographica paper. But this may be secondarily derived.
Andrzej Elzanowski, Gregory S. Paul, and Thomas A. Stidham: An avian
quadrate from the Late Cretaceous Lance Formation of Wyoming, JVP 20(4):
712-719 (December 2000)
describes said right quadrate as *Potamornis skutchi* and assigns it
tentatively to Hesperornithiformes (apart from resurrecting Odontognathae).
Supplementary diagnosis of Hesperornithiformes -- "Head undivided or the
division only barely indicated. Pterygoid [...]"
>From the description -- "In dorsal view, the head shows a slight waist at
the proximal third of its long diameter [...], which may or may not indicate
its former division into the otic and squamosal capitula. Another possible
vestige of this division is a shallow pit that opens rostrally and separates
the minor, most medial part of the head from the rest. A similar pit marks
the boundary between the otic and squamosal capitula in the partly (and
sometimes completely as in *Francolinus*) fused head in the Phasianidae
[chickens, pheasants...]. However, the waist and the pit do not coincide and
thus only one of them may indicate the former division."
>From Table 1, Terminology of the avian quadrate --
Caput quadrati (4)
(4) In many birds it is undivided or incompletely divided, hence a need of
>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 (Elzanowski
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. However, as far as preserved, the
conformation in the seventh specimen of *Archaeopteryx* does not seem
compatible with the presence of a broad head with two widely separated,
approximately equivalent capitula seen in extant birds, but it could be
compatible with the configuration found in the oviraptorids, in which the
apex of the otic process is formed by the prominent lateral (squamosal)
capitulum and the medial capitulum is attached just below, on the medial
slope of the lateral capitulum (Marya´nska and Osmólska, 1997). The
oviraptorids show many other avian similarities and their close avian
relationships have been suggested (Elzanowski, 1999)."
"In some [...] [recent birds] there seems to be a morphological continuum
between a perfectly single head and the presence of two distinct capitula.
The lack of a distinct division in such unrelated and highly derived taxa as
*Nycticibius*, *Opisthocomus*, Phasianidae, and Spheniscidae suggests that
this condition evolved more than once and is secondary in some neognaths."
"The quadrate is pneumatic in some theropods, including the oviraptorids
(Marya´nska and Osmólska, 1997), tyrannosaurids, ornithomimids and
troodontids (Witmer, 1997), but it remains unknown whether it was pneumatic
in *Archaeopteryx* and *Gobipteryx*. The quadrate is pneumatc in the
majority of other birds except *Apteryx*, *Paracathartes*, and many diving
birds including [...]"
BTW, *Mononykus* has a double-headed quadrate.
> What is a proto-pygostyle, if it doesn't have to be fused?
Ermmm... heh heh :-]
Basically, I'm referring to the fact that the SVP meeting abstract on
embryology that I've cited a month or two ago finds a *Nomingia*-like
pygostyle in embryonic birds, and to the fact that anything like a pygostyle
has so far only turned up in birds and oviraptorosaurs, even though not in
all of the latter. Additionally, I'm not totally sure that the last caudal
of *Caudipteryx* doesn't actually consist of 3 fused caudals, the latter two
of which are tiny -- fuse this bone with the 2 vertebrae in front of it, and
you get something that looks a lot like the pygostyle of *Nomingia*.
However, the last 2 of the 5 vertebrae in the latter's pygostyle are
slightly discernible by suture lines, whereas the terminal caudal of
*Caudipteryx* (number 22, IIRC) shows no sutures, as far as I can tell
without having seen the actual bone through a microscope. It _might_ be
significant that only the tail tip of *Caudipteryx* and *Protarchaeopteryx*
Are any segnosaur tail ends known?
BTW, not that I'm citing this as evidence -- some BANDit has mentioned the
"pygostyle" of *Caudipteryx* as evidence it is a bird sensu BAND :-)