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Re: *Jeholornis* (Archaeopterygiformes: Rahonavidae)??



David wrote:
>
> Sorry, I assumed their dentaries [Caenagnathid] (not their whole lower
jaws) were shorter.
> False memory strikes again. :-) Unfortunately I can't find a caenagnathid
> lower jaw in lateral view at the moment. -- But their symphysis is much
> longer than that of *Jeholornis*, so it's still not similar... and I can't
> find the famous caudal bifurcation of the dentary. Doesn't argue against
it
> being a very basal oviraptorosaur, but doesn't argue for it either.
>
Multiple jaws were available on Qilong, but this has since moved to another
website (BTW HP Jaime, when will Qilong be completely up?). A shorter
sumphysis agrees with a more basal position for Jeholornis, otherwise, the
long symphysis would not be much of a derived character compared to J.
prima.  Agreed on the latter argument though, as well as with your
conclusion. Untill an in-dept monograph about the osteology for Jeholornis
will be presented, or about the Maniraptorans from Liaoning in general, we
all must have to rely on the short descriptions found in publications like
Nature, Science and JVP. :(
>
> > Second, a slender dentary is in line with the dentary observed in
> > Archaeopteryx, impying it's connecting position between Archie and
Ovi's.
>
> In that case it's a plesiomorphy...
>
No derived characters without plesiomorphies ;)
>
> Just trying to weight characters. :-) Devil's advocate is a well-paid job.
>
But unfortunately for Keanu Reeves, things just didn't work out for him...
=)
>
> Which might one day turn out as a synapomorphy of "enigmosaurs" +
> Avebrevicauda... I have to get some numbers sometime.
>
Thanks to HP Mickey Mortimer I received this small list of genera which show
this characteristic (thanks BTW):

"I'd say oviraptorosaurs (Incisivosaurus, Caudipteryx, Caudipteryx? sp.
nov., Chirostenotes, Oviraptor, "Rinchenia", Citipati, Conchoraptor, Khaan,
many unnamed oviraptorid specimens), probably Avimimus, Jeholornis,
Confuciusornis, Changchengornis, Gobipteryx and ornithuromorphs at least.''

With Confuciusornithes as Ovi's, things should work out OK ;) But it would
not unite the ''enigmosaurs'' as a whole with the Abrevicauda, since
Therizinosaurs don't have this feature preserved when skull material is
available (which isn't that much I must say...), but it should just be a
characteristic uniting the Ovi's with the Abrevicaudans. Therefore, giving a
possibility that Jeholornis is indeed an Ovi as originally said and
advocated and not an abrevicaudan (big hint: no pylogostyle) as the other
Avian genera do have a pylogostyl present in the material or in life.
>
> > Meaning?
>
> --+----+--*Archaeopteryx*
>   |    `--+--*Rahonavis*
>   |       `--*Jeholornis*
>   |
>   `--Avebrevicauda (and who knows what else)
>
Possible... Have to look into the supplementary material in the
Jeholornis-paper for additional comments and comparisons to Rahonavis.

But than again, using your phylogenetic tree as a guide, you could end up
with this:

--+----+---+--*Archaeopteryx*
   |       |  `--+--*Rahonavis*
   |       |       `--+--+--*Jeholornis*
   |       |           |     |
   |       |           |     `--Oviraptorosaurs
   |       |           `--Therizinosaurs
   |       `--Deinonychosaurs
   `--Abrevicauda

This is not based on running a cladistic experiment in PAUP using the
characters from multiple references, but more a sort of possible consensus
tree between the opinion you have and the opinion I have (with the
additional gut-feelings of course =)). This tree seems to be preserving both
ideas in a way that is a possible phylogenetic outcome. It could also
explain the result Maryanska had with their paper on the Avian Status of the
Ovi's in the more birdlike features that are retained in the skeleton. But
hey, it's just MHO.
>
> > Is this a compliment? ;)
>
> Sure. Because you _got the idea_ of comparing it with oviraptorosaurs (and
> did that in some detail), while the original describers apparently didn't,
> there are none in their cladogram, and the text doesn't mention any.
>
*(blush)* ;) Thanks!