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alvarezsaurs and hypapophyses
On gnetophytes etc, Nick L asked...
Do either of these guys have any fossil record at all?
Yes, gnetophyte pollen is known from the Triassic and the Cretaceous
and is apparently near-indistinguishable from that of _Ephedra_. Work
on gnetophyte phylogeny indicates that _Welwitschia_ diverged during
the Cretaceous I believe (the ucmp website had a good section on
gnetophyte fossils but wasn't working last time I checked). If the
Triassic record is valid then, as some have argued, it might be that
angiosperms originated in the Triassic.
Fond as I am of Nick's suggestion that alvarezsaurids might have been
ant-eaters.. Nick, have you looked at a tarsipedid (honey possum)
skull? Obviously lacks the postcranial specialisations seen in
alvarezsaurids and extant myrmecophagous forms but the skull
morphology is superficially similar.
Haven't looked at them. To the extent that nectar feeders and
myrmecophages need to extend their tongues as far as possible into
tight spaces to lap up food, they should look the same, so I guess
the question is how they would differ; I'm not sure. Regarding bees
as a food, I'm sure it's possible, but ants and termites are more
abundant in most environments and so more things specialize on them,
also they have much harder nests, demanding much more specialization
of the forelimbs. Then again bees will nest in logs and such.
Darren was mentioning hypapophyses a while back. I've been
seeing these around a bit- a while back, I noticed some in
Compsognathus and figured that might throw it in to Maniraptora, but
then I noticed that some pretty damn large ones are present in a
specimen of Allosaurus as well, along with Sinraptor of course so
this means that character isn't particularly informative (they are
even larger in e.g. alvarezsaurs, oviraptorosaurs, deinonychosaurs
tho so they support these guys as a clade). Other stuff- pubic boot
is also pretty long in Allosaurus and tyrannosaurids so I'm not sure
about the long boot pulling Compsognathus out with Coelurus.
Fan-shaped neural spines are definitely present in at least some
ornithomimids. In short: Compsognathus is presumably somewhere
between basal Coelurosauria and basal Maniraptora, I wouldn't want to
say much else. Sinosauropteryx is a tetanuran, and until some decent
photos/description come out on the larger specimen, hard to say much
more than that.