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Re: Paravian questions
Nicholas Gardner wrote-
> Sacral transverse processes and ribs are longer than the transverse
> of the caudals and the dorsals
> What does "transverse" mean? And is HP Marjanovic's synapomorphy valid?
Haven't checked the validity of that yet (will soon though, as I need sacral
characters for my big analysis- currently measuring sacral central
Transverse processes (also known as diapophyses) are the processes that
project laterally on vertebrae. They are usually centered on the neural
arch, behind the prezygopophyses, in front of the postzygopophyses, below
the neural spine and above the centrum. The ribs articulate with them and
the parapophyses in cervicals and dorsals. Distal caudals lose their
transverse processes past the transition point.
Transverse itself means perpendicular to the long axis in this case, running
from left to right.
> Does anyone have any quality photographs of NGMC 98-5-003
They are not published.
> Is the magnum foramen posteroventrally oriented in any particular
> non-neornithine dinosaurs?
Yes, such as ornithomimids, Bambiraptor and many avians.
> What are the synapomorphies for the Neornithes?
According to Cracraft and Clarke (2001), the following are. Those marked
with an asterisk are ones I've looked at for my coelurosaur analysis.
*- edentulous maxilla and dentary
Also in ornithomimids, oviraptorosaurs, Yandangornis, confuciusornithids and
*- coronoid absent
Possibly in ornithomimids, segnosaurs, caenagnathids, mononykines and more
basal avians. However, this was thought to be true in oviraptorids until
Citipati's holotype was discovered a couple years back. So we must be
cautious when determining which taxa truly lack small easily lost elements.
*- fused dentary symphysis
Also in caenagnathids, Jeholornis, Changchengornis and Gobipteryx.
- ossified eustachian tubes
- increased tympanic pneumaticity
*- quadrate with three mandibular condyles
Also in Erlikosaurus, Sinornithosaurus, Patagopteryx and Hesperornis.
Baptornis and Ichthyornis lack it though. So, ignoring the non-avians
(Archaeopteryx, Jeholornis, Confuciusornis, Changchengornis, the Spanish
nestling and Gobipteryx all lack it), it either developed in
euornithines/ornithuromorphs and reversed in Baptornis and Ichthyornis, or
developed in parallel in Patagopteryx, Hesperornis and neornithines. Each
requires three steps.
*- more than ten sacral vertebrae
Also in Hesperornis.
- first sacral vertebra heterocoelous
- gastralia absent
- deltopectoral crest cranially deflected
- pneumatic foramen in humerus
- posterior end of obturator foramen strongly demarcated
- ilium extends anteriorly to overlap base of at least one set of ribs
- suptratendinal bridge on tibiotarsus
- hypotarsus with well developed crests and grooves
- two or more proximal vascular foramina on tarsometatarsus