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Re: A non-Jurassic non-beaver



David Marjanovic (david.marjanovic@gmx.at) wrote:

<...>

  I have been following this closely for some time, when I presented on the
2005 date, and have of late been equating the Daohugou beds with the lowermost
Yixian, perhaps contemporaneous and laterally equivalent with the Lujiatun beds
of the lowermost Yixian, which seem so distinct and faunistically distinct from
the overlying Sihetun member as to permit geological stratigraphic utility of a
Lujiatun fauna. Czerkas argued that *Scansoriopteryx heilmanni* derived from
the Yixian, but only because similar fossils were more popularly from the
Yixian, and were not considered otherwise; the actual *S. heilmanni* holotype's
recovery is unknown, since it was "found" in a trade show in the USA, NOT _in
situ_. By contrast, the similar, if not synonymous *Epidendrosaurus
ningchengensis* is from Daohugou, and may argue that *S. heilmanni* is also
from the Daohugou, or is a horizontally consistent taxon from Liaoning.

  While I typically despise biostrat as anything more than a subjective
interpretation of subjective lumping or splitting, Daohugou to date shows
consistent affinities with basal Yixian beds, which show distinct faunal
compositions to the Sihetun fauna, while at the same time showing little real
apparent overlap with the underlying Tuchengzi, who's only apparent dinosaur is
the ?psittacosaurid *Chaoyangsaurus*.

  Cheers,

Jaime A. Headden
http://bitestuff.blogspot.com/

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

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