Re: extinction in China

["Rob Gay" <rob_redwing@hotmail.com>]

Zhao's principal motivation was to strengthen the case for continuous 
deposition during the K-T interval in the Nanxiong basin.  Most researchers, 
e.g. Russell, maintain
that the Nanxiong (or Pingling) - Shanghu contact is disconformable, an 
opinion apparently based at least partly on the lack of an iridium anomaly 
there.<
Lack of iridium across the boundary can be explained by reworking of the 
iridium, if you are indeed getting constant deposition. Similar situations 
are not common, but do occur across the KT Boundary.

> Does it support a specific alternative?  It is interesting that Mikhailov 
> suggested the Macroolithus egg type was laid by T. bataar, inasmuch as it 
> is the largest of the elongatoolithid eggs of presumed theropod
affinities, and abundant, like T. bataar, in the Nemegt svita e.g. at Tsagan 
Khushu.<
Or a therizinosaur, which has also been suggested. Unless you have an 
embryo, or a parent on the nest, you can't say for certain what laid those 
eggs. And, as for disappearance, as HP Irmis brought up onlist a week or two 
ago, disappearance from the fossil record is not entirely equivelent to the 
extinction of an organism.

> The Nanxiong record may be relevant to global extinction in that it 
> demonstrates Tyrannosaurus radiated into paleoenvironments where it did not 
> belong c. 65 Ma, with devastating results.<
Until you can prove that the eggs were laid by a tyrannosaur, and that there 
was overpredation in the fossil record, then this hypothesis is untestable.
Peace,
Rob


Student of Geology
Northern Arizona University
Biological Science Tech
Manti-La Sal National Forest
AIM: TarryAGoat
http://www.geocities.com/elvisimposter/dinopics.html
http://www.cafepress.com/RobsDinos
"A _Coelophysis_ with feathers?"

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