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

Re: Mei example



> Archaeopteryx is closer to birds than oviraptorosaurs are because it has-
> - elongate distal caudal vertebrae.
> Lacking in short-tailed birds; also present in Ornitholestes and
> Alvarezsaurus.

So... if short-tailed birds were shown to either form a single clade or to
be closer to dromaeosaurs, scansoriopterygids or suchlike, or both, this
character would disappear from this list.

> - proximal caudal centra rectangular in transverse section.

Where have you found such a character? In Makovicky's thesis?

> - reduced number of caudals with transverse processes.
> Lacking in dromaeosaurids and Sinornithoides.

I've recently seen the skeleton of an adult ( = huge!) chicken several
times. Its transverse processes continue unambiguously into the pygostyle -- 
and take into account that the _proximal_ caudals, those that alone bear
transverse processes in long-tailed birds, have ended up near the middle of
the sacrum!
        Of course this could be a reversal. In *Sinornis* the last two free
caudals seem to have no transverse processes... but the proximal part of the
pygostyle does have a shelf that looks like a few fused transverse
processes. In general transverse processes seem to continue into the
pygostyle when one is present, *Nomingia* and (IIRC) *Beipiaosaurus*
excluded (whose pygostyles are quite short).

> - distal chevrons bifurcated anteriorly.

Distal chevrons are lacking in short-tailed birds. (The chicken mentioned
above doesn't even have any chevrons at all.)

> - low number of maxillary teeth.
> Lacking in Aberratiodontus; also present in Scipionyx (ontogenetic?).

I wonder how much this is related to size... and of course to snout length.

> - jugal process of palatine absent.
> Also present in Shuvuuia, Erlikosaurus and Incisivosaurus.

And unknown in just about any Cretaceous bird except *Gobipteryx* and
*Hesperornis*, right?

> - even more elongate distal caudal vertebrae.
> Lacking in short-tailed birds; also present in microraptorians.

I have this in my matrix, and I wonder if it will come out as a synapomorphy
of dromaeosaurs and long-tailed birds. But then a composite *Microraptor* is
the only dromaeosaur in my matrix. -- Short-tailed birds have
extra-shortened distal caudals, much like oviraptorosaurs.