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Extinction Distinctions



There's a few things I'd like bring up. First, a couple of things about 
the recent discussions about extinctions, statistical concerns and the 
man-the-hunter/prehistoric overkill hypothesis. Second is government 
policy towards the collection and sale of fossils from federal land

As for the speed of of extinction events it is just about 
impossible to assertain whether a species went extinct at 
a single catastrophe or whether it diminished over time. This is due to 
sampling error and has been identified as the Signor-Lipps effect. I had 
the chance to talk to Jere Lipps about the effect. He said that one could 
draw a line anywhere in the fossil record and call it a catastrophic mass 
extinction. Even at an arbitrary boundary one would find both gradual and 
sudden disappearances. There's some analysis of the problem in a recent 
article in Science (11 March 1994, Vol. 263 pp.1371-1372 *note inset on 
p. 1372)

Another stastistical concern is about the "periodicity" of mass extinctions 
and the inherent implication of periodic bolide impacts. Jack Sepkoski 
has done much of the work in the area of periodicity. An informal source 
pointed out that the statistical method used by Sepkoski could "find 
periodicity in the phonebook." I don't know enough about statistics yet 
to analyze the claims that are being made. Any thoughts? I have one 
good source for Sepkoski on on periodicity: Sepkoski, J.J. J. 1989 
-Periodicity in extinction 
and the problem of catastrophism in the history of life- Journal of the 
Geological Society of London 146, 7-19.

The Quarternary extinctions are a bit out of the scope of this list but 
they have been brought up by others in a couple of contexts. My gripe is 
with the "prehistoric overkill" hypothesis. The hypothesis has its origin 
in the correlation-as-causation association of human habitation in North 
America and the extinction of terrestrial megafauna. Correlations have 
also been made with extinction/habitation in Australia. 
Problem: the dates for human habitation are consistently being pushed 
back _well_ beyond 11,000 b.p. for North and South America, (see Meltzer, 
David J. 1989, -Why Don't We Know When the First People Came to North 
America- American Antiquity 54, 471-490 and Whitley, David S. 1993, -New 
Perspectives on the Clovis vs. Pre-Clovis Controversy- American Antiquity 
58, 626-647). The same is true for Australia where human contact is now 
placed at 40,000 b.p. One might make the case for a major cultural change 
that led to the over hunting of megafauna, but that requires some special 
pleading. 

That people hunted megafauna is not in doubt. Overkill is a projection of 
the man-the-hunter stereotype into the past. The past is a place, and the 
overkill hypothesis makes a place where it is "natural" for humans to 
drive species into extinction. This projection into prehistory serves as 
a justification for the contemporary human mediated extinctions. 

With regards to the whole Sue thing, and in view of the classified ad for a 
mammoth (perhaps it was a white elephant sale?), I'm surprised that 
nobody has brought up the Baucus bill. This bill is an attempt to make 
governmental policy towards vertebrate fossils on federal land explicit 
and consistant. There was a commentary in Time (or Newsweek) that knocked 
the Baucus bill saying that it would stop boy scouts from collecting 
fossils. That is just one of the untruths currently circulating about the 
bill. I strongly suggest that you read the whole text. I don't have the 
ability (time) to reproduce the whole bill here, but you can check it out 
in the February 1994 (number 160) Society of Vertebrate Paleontology News 
Bulletin. In general, I'm against adding new laws. We've got too damn 
many overlapping and contradictory rules and regulations as it is. In 
this case I support the addition because it clarifies relationships, 
defines terms, and makes policy _explicit_. Beyond the bill, I firmly 
believe that what paleontology really needs is the level of 
volunteer-professional-amateur coordination that bird groups such as the 
Audoban Society. It was Bob Bakker that expressed this sentiment quite 
nicely in "The Dinosaur Heresies." Working together makes more sense than 
legislating paleontology out the wazoo. While the Baucus bill only 
applies to public lands it establishes a frame work and sets a tone.

Have fun this summer,

                        Erik

Erik Pauls, Student
erik@uclink.berkeley.edu