Epidendrosaurus, Systematic Observations pt. 1

["Jaime A. Headden" <qilongia@yahoo.com>]

Okay,

  The "Part 1" refers to this post being a preliminary observation. The
part two will have me running the analysis in someone else's trees, but
for now this is essentially just a first step: analyzing what's been
published.

  http://qilong.8m.com/Epidendro.html

  includes the re-run analysis (Forster_Rahonavis Epidendrosaurus.nex,
.tre, and epidendro.txt for the output results -- there may be problems
with the .nex files on the page, I can email it to you) as published by
Zhang et al., 2002, in _Naturwissenschaften_ (published online, and much
thanks to Ben Creisler for getting this for me). Zhang et al. used Forster
et al.'s *Rahonavis* analysis, and coded *Epidendrosaurus* for 34 of the
113 characters, 30% of the matrix. Problematically, I could verify only 12
of these, whereas I noted almost the entirety of the rest of their codings
were wrong, or based on questionable interpretations. Where is could
_sorta_ see the condition, I recoded with variable, bipolar states (01),
(1?) in order to provide the matrix with more data. After recoding, I had
only 29 characters of 113, and this accounts for a low percentage (26%) of
the matrix.

  Nonethless, the analysis provides three MPT's of 239 steps each, and
*Epidendrosaurus* is placed in three positions: the sister group to the
ornithomimid clade, the sister group to the troodontid+bird clade
(exclusive of dromaeosaurids), and the sister group to the
Archaeopteryx+bird clade (exclusive of both troodontids and
dromeosaurids). Synapomorphies for these are listed below, with position
one as characters A, position two as B, and so on.

  Characters:

A:
  2(2): teeth lack denticles.
  7(1): frontals triangular from above and narrow rostrally.
  9(1): frontals at least nearly as long as twice that of the parietals.

B:
  7(1): frontals triangular from above and narrow rostrally.
  9(1): frontals at least nearly as long as twice that of the parietals.
  59(1): radius thinner than ulna, diameter less than 0.7.
  66(1): manus longer than ulna by 20%.

C:
  3(1): teeth slightly compressed and nearly conical.

  The concensus tree collapses at Maniraptoriformes, but Aves remains
resolved. Both bootstrap and jackknife analyses refuse to resolve the
position, and no support is given to *Epidendrosaurus* other than
Maniraptoriformes, despite the authors placing this taxon between
Troodontidae and Aves, as in tree #2.

  Hopefully, adding *Epidendrosaurus* to the Holtz and Xu et al./Hwang et
al. matrices may resolve this slightly, but the data is hampered by poorly
preserved vertebrae, no pelvic material, poorly preserved femora, the
tibia exposed in posterolateral view, and probably an hourglass-shaped
element on the left tibia that may be part of the astragalus, and not much
of the skull. The authors coded several features of the tail and sacrum
that are plainly just not there.

  I have attempted a restoration of the skeleton that (hopefully) improves
on that provided by the authors, and it is at:

  http://qilong.8m.com/Epidendrosaurus_ningchengensis_skeleton.jpg.

  And I guess with the latter, I suspect some on this list think of me as
just an educated artist ... I wonder why....

  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.

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