RE: Haha, even more questions

[Josh Smith <smithjb@sas.upenn.edu>]

Quoting "Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>:

> 
> 7) Is a vulcanic eruption the cause of the major faunal death
> in the Lianoning basin or are there other theories as well?
> 
>   A serious taphonomic study of these beds have yet to be
> attempted.  I will point out that although the sediment is believed
> by many to be volcanoclastic, that doesn't mean that the faunal
> assemblage therein must necessarily be victims of the various
> blasts.  They may simply be accumulating into these bodies of waters
> by ordinary attrition, but the bottom mud happens to be
> volcanoclastic. (That being said, there is preliminary evidence that
> at least some horizons in there might be mass kills: Confusciusornis
> bone beds, for example).
> 
Some of the silts from the basal Yixian are certainly volcanoclastic 
and there are ash falls in the sequences which are by definition 
volcanic in origin and fall, according to many, into that gray area 
between igneous and sedimentary rocks.  However, there is ZERO 
scientific evidence that these "Confusciusornis horizons" are the 
result of volcanic activity.  This isn't a theory in the scientific 
sense...far from it.  It is a hypothesis.  That these horizons are the 
result of volcanic activity has been speculated on in several places, 
but no data have yet been generated. Moreover, as Tom stated, even in a 
volcanically active basin setting such as Liaoning in the Barremian (I 
am ignoring the Jurassic speculations for this post on the basis of the 
available data), volcanic activity doesn't kill everything.  No 
detailed petrographic analysis currently exists in print of the Yixian 
sediments and given the collection and excavation practices that are in 
place regarding this biota, it is, in my opinion, very unlikely that 
the taphonomic study that Tom and I both want to see happen will ever 
get done.  Indeed, enough data has been lost that at this point the 
results of such a study would be open to significant ranges in 
interpretation.  

-josh

----
Josh Smith
Department of Anthropology
Harvard University
18 Traymore Street
Cambridge, MA 02140
Office: 617.495.1966
Director, Bahariya Dinosaur Project http://egyptdinos.org

After 1 August:
Josh Smith
Assistant Professor of Geology
Department of Earth & Planetary Sciences
Washington University
Campus Box 1169
1 Brookings Drive
108 Wilson Hall
St. Louis, MO 63130-4899
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Phone: 314-935-4258  FAX: 314-935-7361
smithjb@levee.wustl.edu
http://epsc.wustl.edu