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

Re: Scaly tyrannosaurs; fact or fiction?



David Marjanovic wrote-


> How come? Do interpretations of the tyrannosaur carpal differ? (standard
> interpretation AFAIK: fusion of semilunate + radiale + ulnare ?+ distal
> carpal 3)

Tyrannosaurids had five carpals, including one corresponding to the
maniraptoran semilunate, like ornithomimids.  This doesn't affect their
placement versus compsognathids though, as Compsognathus was described as
having two carpals (although more were probably present), both flattened.
The carpals of Sinosauropteryx are neither described, nor figured.  The
carpal morphology of compsognathids is thus uncertain, although it doesn't
seem that different from tyrannosaurids at this point.  The best characters
that support (Tyrann (Compso + Manirformes)) in my cladogram are-
- nasal subequal in length to frontal
- orbit longer than antorbital fenestra
- lateral temporal fenestra dorsoventrally shorter than orbit
- low cervical neural spines
- pubic peduncle projects ventrally
Not very many, but like I said, this part of the cladogram is prone to
rearrangements.  It was only recently that "basal coelurosaurs" and
ornithomimids got out of the polytomy with tyrannosaurs and
maniraptoriformes that they were in for so long.  I'm not saying I
neccessarily support tyrannosaurs being outside the
Compsognathidae+Maniraptoriformes clade, but I want people to realize
phylogenetic bracketing doesn't insist tyrannosaurs had feathers.

> As long as I don't know whether my paper has been published (cheer up, I
> might know this tomorrow ;-) ) I won't say more than "heh, heh". I do
agree,
> however, that the dromaeosaurids are the closest known relatives of
> *Archaeopteryx* (and *Rahonavis*, maybe), just I can't find synapomorphies
> linking exclusively *A.* and pygostylians, except for probably the
reverted
> hallux (convergence? whatever) and the triradiate palatine (I don't know
> what Elzanowski has to say on this, I haven't read his latest paper;
> convergence? whatever).
>     Just forgot, who's Jackson?

Well, my current cladogram has Archaeopteryx as the basalmost
deinonychosaur, so I can't help you with synapomorphies shared by
Archaeopteryx and pygostylians, exclusive of dromaeosaurs.  Deinonychosaurs
are still the sister group of Yandangornis+Pygostylia however.  Elzanowski
never mentions the triradiate palatine of Archaeopteryx, though I should
note that oviraptorids have this character too.  As caenagnathids lack it,
it was probably due to convergence.
I was speaking of John Jackson, former dinosaur list member and advocate of
secondary flightlessness and paraphyletic pygostylians.  Very unique
phylogeny.  Read more at his website:
http://www.geocities.com/strangetruther/jj2ftree.html  .
Regarding your phylogeny, I'd be interested to know what you place as the
sister group to Pygostylia.  Oviraptorosauria?

> It isn't the recently announced Jeholosaurus, is it?

No, and I'm personally not convinced the specimen in question supports the
theory of integumentary filaments on ornithischians.  I'll have to wait for
the paper to get the needed details I guess... :-(

Mickey Mortimer