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

Re: Enantiornithines and Iberomesornis



Mickey Mortimer (Mickey_Mortimer111@msn.com) wrote:

<Regardless of the likely paraphyly of enantiornithines as currently
conceived, the characters used by Sanz (1988, 1995) and Chiappe (1995) to
place Iberomesornis below their level have been nicely eliminated by
Sereno (2000).

 - The posterior cervicals of enantiornithines (eg. Eoalulavis, Catalan
nestling) are also amphicoelous.>

  This is true of many birds, as in *Confuciusornis* and more advanced
birds.

<- Prominent hypapophyses are present on the last cervical and the first
three dorsals.>

  This is a synapomorphy of the Oviraptorosauria + bird clade, is it not?
With significant appearance in later birds, suggesting multiple loss to
reduce neck flexibility or length, as in possibly dromaeosaurids, etc..

< - There are eight, not five sacrals.>

  Lü et al. pointed out that nearly all pygostylians have more than seven
sacrals at adulthood.

< - The scapulacoracoid articulation is not preserved.
  - The transverse groove across the humeral head is not definitely
 present, but is variable in enantiornithines anyway.
  - The radial condyle is not preserved, and the ulnar condyle seems to
round on to the anterior side of the humerus.
  - Pelvic fusion is variable in enantiornithines, and partially developed
in Iberomesornis.>

  This data tells us nothing, unfortunately.

<- The proximal tarsals are completely fused to the tibia.
  - There are no free distal tarsals.>
  
  As in most ornithurines, I beleive.

<Thus, the "alternate hypothesis" of placing Iberomesornis basal to
classic enants like Sinornis, Eoalulavis and Concornis is effectively
dead.>

  I beg to differ. And the Enantiornithiformes has been considered the
only stable clade within the group, whereas the others are easily unstable
and may reflect the reason why cladistics has found such weak evidence for
placing them there. Have you looked at the bootstrap values?

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
http://mailplus.yahoo.com