From: "Mickey Mortimer" <Mickey_Mortimer111@msn.com>
Reply-To: Mickey_Mortimer111@msn.com
To: <dinosaur@usc.edu>
Subject: Re: noasaurids strikes back
Date: Mon, 19 Apr 2004 16:19:56 -0700
Jordan Mallon wrote-
> >However, noasaurids differ from velocisaurids in having a specialized
> >raptorial ungueal structure.
>
> Has this been shown to be true yet? I understand there has recently
been
> some doubt circulating about whether or not Noasaurus did, in fact, have
a
> "raptorial" claw. Where did this doubt come from? What's the reasoning
> behind it? I know Tracy Ford made a reconstruction in which the
supposed
> sickle claw is placed on the hand...
Regardless of the condition in Noasaurus (which Apesteguia et al.
apparently
have new information regarding), Ligabueino would appear to have a
hyperextendable pedal digit judging by its illustrated phalanx. This bone
exhibits the prominant proximoventral heel seen in pedal phalanx II-2 of
deinonychosaurs, and has a protruding dorsal articular surface. This is
unlike Elaphrosaurus or the preserved phalanx of Noasaurus. A similar
morphology is not mentioned for Masiakasaurus, but the pedal description is
brief and the elements unillustrated (besides the skeletal reconstruction).
B B wrote-
> Does anyone know the basis for Deltadromeus being a noasaurid? From
what
I
> last heard it had a large number of similarites to Dryptosaurus. Is
there
> any possibility that it could be chimerical? What about Bahariyasaurus?
Is
> it a noasurid too or is it closer to Dryptosaurus or Tyrannosaurs. I
saw
a
> drawing of what was supposed to be the pelvis of Bahariyasaurus and it
> looked to be very similar to the pelvises of Tyrannosaurs, but I could
be
> mistaken.
It's based on a pdf from Sereno's website-
http://www.paulsereno.org/012204.pdf . Previously, several people have
hypothesized Deltadromeus is more basal than coelurosaurs (Longrich DML
2000; Carrano et al., 2002), though it came out in Coelurosauria in a
couple
phylogenetic analyses (Holtz, 2000; Rauhut, 2003).
Deltadromeus is NOT very similar to Dryptosaurus. Curse the one who
started
that "fact". So they start with D and were considered large basal
coelurosaurs for a while, big deal. Deltadromeus is turning out to be
ceratosaurian, and Dryptosaurus is probably a tyrannosauroid. As I wrote
back in 2001- "Both have somewhat similar deltopectoral crests, but
Dryptosaurus' humerus is more developed proximoposteriorly and seems more
sigmoid. Deltadromeus has an oddly anteroposteriorly narrow femoral head
and an anterior trochantor that starts further distally. Deltadromeus'
lateral tibial condyle has an odd posterior process, the cnemial crest is
narrower and the incisura tibialis is more excavated in proximal view.
Deltadromeus has a better developed proximomedial fibular fossa, but it is
not as extensive proximoposteriorly. Dryptosaurus' ascending process is
much higher and more pointed and it lacks the plesiomorphic transverse
groove across the astragalar condyles found in Deltadromeus. Metatarsal IV
is much narrower in Deltadromeus and it's proximal end is less triangular
than Dryptosaurus and tyrannosaurids, and lacks the notch found in those
taxa. Deltadromeus' humerus is 6% longer compared to femoral length, but
its tibia is 6% shorter. As you can see, the taxa are rather different,
although a better description of Deltadromeus would make it easier to
compare them."
You can find info on the Bahariasaurus-Deltadromeus issue in the
excruciating debate between Jaime and myself back in August-September of
2003. The issue is complicated by questionable referrals and the differing
identification of pelvic elements. My conclusions at the end were- "I'd
say
Deltadromeus and Bahariasaurus are quite possibly synonymous, but this is
unverifiable given the published data. There were at least three taxa of
large theropod in the Baharija Formation, so it cannot be assumed the
referred material belongs to Bahariasaurus. This leaves us able to compare
only the proximal ischium, which is illustrated too poorly in Deltadromeus
to do such. Some material from the Baharija may be referrable to
Deltadromeus (notably the fibula 1912 VIII 70), and some to Bahariasaurus
(the proximal ischium 1912 X 47), but neither can be compared to the other
taxon. The complete ischia 1912 VIII 82 compare well to Deltadromeus
distally and differ in small ways from Bahariasaurus proximally, but I
don't
think a referral to the former is warranted given the meager comparison
possible, and the fact we don't know how closely they resembled
Bahariasaurus distally." As for what Bahariasaurus is, neither the
carcharodontosaurid nor tyrannosauroid identifications are well supported,
as I show here- http://www.cmnh.org/dinoarch/2002Aug/msg00488.html . But
again, problems with which remains are correctly referred makes it
difficult
to place with much certainty.
Sebastian Apesteguia wrote-
> Velocisaurus and
> Masiakasaurus share slender metatarsals II and IV, and very gracile and
> non-raptorial pedal phalanges with a long dorsal process. This features,
> which distinguish them from other abelisauroids, prompts the inclusion
of
> the latter within Velocisauridae. Additionally, a reduced and thin 2nd
> metatarsal, suggest close relationships with the noasaurid Noasaurus
leali
> Bonaparte y Powell. However, noasaurids differ from velocisaurids in
having
> a specialized raptorial ungueal structure.
But wouldn't the condition in Noasaurus be autapomorphic, thus NOT helping
to place 'velocisaurids' together to its exclusion, and making Noasauridae
a
senior synonym of Velocisauridae (both under ICZN and Phylocode rules)?
Mickey Mortimer