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Re: Jeholornis prima discussion
----- Original Message -----
From: "Mickey Mortimer" <Mickey_Mortimer111@msn.com>
Sent: Saturday, July 27, 2002 4:34 PM
> There are twenty-two caudal vertebrae,
There are 21 preserved caudal vertebrae. At least one (number 14) is
missing, but who knows how many more? (Can't be many, judging from the
relative sizes of the vertebrae, but one or two more should be possible,
> Interestingly, Zhou and Zhang report new Sapeornis material indicates it
has only two reduced phalanges on digit III, like Protopteryx, Longipteryx
Every specimen introduces more convergence among early birds. That makes one
pessimistic. I can see the day when people will introduce weighting into
their analyses because they'd otherwise get one huge polytomy from
*Archaeopteryx* to *Apsaravis*... <shudder>
(Wow, that's the worst I've sounded like in my life. :-) )
> The most important feature may be the ascending process, which very
clearly arises from the astragalus, while ABSRDists claim birds' is
associated with the calcaneum (and is thus a non-homologous feature they
call the pretibial bone).
Not mentioning the separate pretibial bone of *Dilophosaurus*.
> This should quash that theory, if Feduccia et al. are even taken seriously
by anyone anymore.
Martin accepts that it's a bird: http://www.msnbc.com/news/784936.asp.
> What's Jeholornis related to?
> A good question. Zhou and Zhang added it and Rahonavis to Norell and
Clarke's Apsaravis matrix, and deleted hesperornithiformes for some reason.
Doing the latter amusingly made pygostylians primitively toothless, with
Gobipteryx as the most basal enantiornithine because of this.
And that got through peer-review...
> Judging by some quick comparisons, it's more derived than Archaeopteryx
based on the [...] less than eight caudals with transverse processes,
More derived, certainly, but not more birdlike. Like in *Nomingia*, in birds
there are transverse processes even in the pygostyle.
> [...] scapulacoracoid joint mobile,
> [...] It shares the mobile scapulocoracoid joint and fibula that does not
contact the tarsus with Rahonavis, as well as the sickle claw (though that
is probably symplesiomorphic). The elongate proximal caudals and
universally dorsoventrally compressed chevrons are shared with Microraptor.
Compared to Yandangornis, it is more derived in having semi-heterocoelous
cervicals. The two genera share several characters- toothless maxilla,
maxilla reduced in size compared to premaxilla, less than six caudals with
transverse processes, elongation of caudal centra to over three times
centrum height starts at at least fifth vertebrae, fibula does not reach
tarsus. I very provisionally refer Jeholornis to the Yandangornithidae
until my coelurosaur analysis is completed.
Problems for me:
-- It's really hard to argue that the last tail vertebra is a pygostyle. It
looks a lot like the last tail vertebra of *Archaeopteryx*. So either it is
closer to *Rahonavis* than to Avebrevicauda (that term was needed... I thank
HP Gregory Paul for introducing it in DA), or the pygostyles of *Nomingia*
and Avebrevicauda are not homologous. A very big photo of that vertebra, in
absence of the specimen itself plus a binocular, would be needed to clarify
this. (Same for *Caudipteryx*.)
-- On the whole the tail is more like in *Archaeopteryx* than like in
oviraptorosaurs, alvarezsaurs and Avebrevicauda. It looks similar to the
drawing of that of *Yandangornis*, but no photo is published of the latter.
_Might_ argue for allying it with *Rahonavis* but not *Yandangornis*. Hm.
-- If it's closer to Avebrevicauda than to *Rahonavis*, then it represents
the third time a scapulocoracoid joint evolved among theropods -- while
pterosaurs never did it.
-- News to me that Shenzhou means China. I only know Zhongguo ( = middle
country). But that's obviously just me, lacking knowledge of Chinese terms
for Chinese history. :-)
Looks like we have to find a much older site with such good preservation, so
old that not everything has lots and lots of confusing autapomorphies. Can
we expect something from Karatau (LJ), if someone pumps some money in there?
Problems in general:
-- Is the hallux of *Shenzhouraptor* really unreversed? It looks reversed to
me, and this doesn't go away when I enlarge the image to 400 % in Microsoft
Photo Editor (that's the best compromise between the effects of magnifying
the image and magnifying the pixels; it also allows one to tell tail and leg
apart and to see that the tail really starts at the sacrum and is not a
break behind the leg).
-- Is *Shenzhouraptor* validly published? If so, does it have priority over
-- Both names bespeak an utter lack of phantasy. The -raptor part is a
minus. *Jeholornis prima* gets two of those: firstly, -ornis is masculine,
prim_a_ is feminine; IIRC the current ICZN doesn't allow anymore to correct
this?; secondly, the authors chose that name because of "the primitive
nature" of the specimen, not mentioning, and apparently not knowing, that
prima simply means "the first". How did that get through peer-review??? (But
then, *Sinovenator changii* got through... grrr.)