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Re: Revising Hou et al, 96 (very very long)
Jaime Headden wrote-
> The issue about
> pubic peduncle orientation may be equivocal, especially in regard to
> debate over *Archaeopteryx* orientation (not that kind!); similar
> orientation of the pubic peduncle with variant pubic orientation suggests
> the key feature is the proximal pubis, missing in *Beipiaosaurus* and
> making the nature of the orientation a definate mystery.
There are instances like Herrerasaurus, where the pubic peduncle orientation
will throw you for a loop, but that's why I said I don't trust what looks
best on Beipiaosaurus to be correct (so it's left uncoded in my matrix).
> Uhm, *Avimimus*? What lachrymal? The refered cranium PIN 3907/3 is so
> well fused and defined it is not possible to determine a condition as to a
> posterior lachrymal, if present at all.
The lacrimal in PIN 3907/1 of course, as described by Kurzanov (1981). The
sutures are only "partially obliterated" and show a posterior lacrimal
process extending back to contact the postorbital.
> The theory that the posterior process is apomorphic of the bone itself
> or is 1) neomorphic, or 2) a fusion of the prefrontal to the lachrymal is
> not resolved yet, though fossils indicate a T-shaped lachrymal element (or
> lachrymal+prefrontal elemental fusion) as a Maniraptora synapomorphy).
It can't be just a fusion of the prefrontal, as many taxa with prefrontals
(including Sinornithosaurus) have the T-shaped lacrimal.
> *Deinonychus* has a broad quadrate foramen [the quadratojugal foramen, as
> I understand it, is the _rostral_ foramen as seen in some "hypsilophodont"
We need a described quadrate to determine the state in Deinonychus, which is
not as Velociraptor-like as often said. Indeed, Barsbold and Osmolska
(1999) say the paraquadratic foramen of Deinonychus was probably smaller
> <6. Elongate distal chevrons and prezygopophyses
> Also in Microraptor, which is even more bird-like (but still thought to
> be a deinonychosaur by many).>
> Yes, and for many other reasons, including the pes construction (an
> apparent troodontid + dromaeosaurid synapomorphy, along with pedal digit
> II features).
That are all also found in Rahonavis, a probable avialan. Paul gives good
support for Archaeopteryx's sickle claw in DA too.
> Seen in troodontids, ornithomimosaurs, blah blah. Probably related to
> small premaxillae. Dromaosaurids proper are larger and may have
> specialized to larger prey, plus they have larger premaxillary teeth and
> hence need a deeper premaxillary corpus ... thus, dromaeosaurids proper
> can have easily reversed this, and the feature can be considered as
> irrelevant by reason of functional morphology and diet-related variation,
> as well as a size-related feature (*whew*! breath ...)
Byronosaurus, yes. Sinovenator, Sinornithoides and Saurornithoides, no.
Struthiomimus and Dromiceiomimus, yes. Gallimimus, no. It's not
size-related, as Microraptor has the a deep premaxillary body. Besides, I
never said my characters weren't homoplasious (virtually impossible in
coelurosaur phylogeny), but the other taxa with them are phylogenetically
distant, arguing for convergence.
> <unserrated premaxillary teeth;>
> Functional, irrelevant, and convergent with other taxa; perhaps diet
No data is irrelevent, most morphological synapomorphies are functional.
I'm sure dental characters are diet-related. You don't see people doubting
the D-sectioned teeth of tyrannosaurids, despite the fact they were
convergent with Pelecanimimus, diet-related and functional.
> <quadratojugal-squamosal contact absent;>
> Also in dromaeosaurids, actually; and variable in some Maniraptora:
> there are two oviraptorid skulls I can show that lack this condition.
No, not in dromaeosaurids (Dromaeosaurus or Velociraptor) actually. There
may indeed be a few oviraptorids without contact, but there are others with
contact. Add Erlikosaurus and Caudipteryx, which both have contact, and you
get good evidence of convergence.
> <smaller angle between scapula and coracoid;>
> As Paul shows, this may be related to loss of flight in the larger
> deinonychosaurs. *Sinovenator* as a basal troodontid shows an "advanced"
> shoulder. So hardly unequivocal.
I concede to that. My old character list I used to compile these did not
> <more than three pairs of sternal ribs;>
> Not exactly ... *Sinornithosaurus* doesn't have that much in the way of
Oh, not at all, with each sternal plate being longer than the sacrum and
supporting about five attachments for sternal ribs. ;-) What insignificant
> <boomerang-shaped furcula;>
> Not in *Sinornithosaurus*; its is rather shallow in aspect when viewed
> from the "top/rostral".
It's thinner than Archaeopteryx, but does have the same morphology. Very
different from Velociraptor.
> <no anterior pubic foot;>
> Not sure the slight flange in *Deinonychus* counts; *Velociraptor* lacks
> this flange, has no projection, and neither does *Sinovenator.*
Well, the pubic foot in both Deinonychus AND Velociraptor (IGM 100/986) does
have a distinct anterior component, so I don't see why they wouldn't count.
It's true troodontids lack an anterior pubic foot.
> <mid-dorsal ischial process;>
> However, this is not always present
> in advanced forms and is of similar functional relevance, and may be more
> equivocal as a result of it's variability.
It IS present in basal avialans though- Microraptor, Rahonavis,
> <fibula <20% of tibia width.>
> Size related.
Which is why Compsognathus lacks it..... we all know how huge it was. ;-)
> <There are also several characters also found in more derived birds, but
> not Archaeopteryx- three distal quadrate condyles;>
> Ah, yes, a "lateral" process below the quadratojugal, seen in
> oviraptorids as well.
No, actually. A third condyle for articulation with the mandible, like some
ornithurines. Most theropods have only two, separated by the helical
> <expanded manual phalanx II-1;>
> In what manner is it expanded?
The distal end is lateromedially expanded, as in pygostylians.
> <no distinct posterior pubic foot.>
> It's big, "hooked", makes the pubis look like a "J" (cf. posts by Pete
> Buchholz a way back in the archives).
Of course it does Jaime, we believe you..... :-) Sinornithosaurus' pubis
expands very gradually towards the tip, then rounds off.
> other features that support the Deinonychosauria and the close
> association of *Sinornithosaurus* to Dromaeosauridae:
> 1. pedal phalanx II-2 with elongation of the ventral edge of the
> proximal articular facet, providing the dorsal extension of the ungual
Like troodontids and Microraptor?
> 2. pedal phalanx II-3 ungual forms raptorial claw.
Like troodontids, Rahonavis and Microraptor?
> 3. elongate posterior flanges of the metatarsals II and IV, converge or
> nearly converge at the midlength.
Like troodontids, Microraptor, Archaeopteryx and probably Rahonavis?