[Aztlan] 13,800 year-old Megafauna die off in North America

[Sid Hollander]

I look forward to reading the details of the full article, but I am left
with several questions in the meantime.  Can the sediments of one relatively
small lake in the center of the Midwest be considered representative of all
lakes across the North American continent?   Can the sediments of one
relatively small lake that is located in a very unique geological
environment be considered representative of all lakes across the North
American continent?     Can the sediments of one small lake that lies just
north of the edges of a band of the major North American glacial moraines of
that period, exactly in the path of where the southern edge of the
Laurentide Ice Sheet oscillated back and forth for several thousand years
immediately following the proposed dating of this study's fungus presence be
considered representative of lakes across an entire continent, particularly
when glacial activity at this moraine ceased prior to 12,000 14C yr B.P.
(13,950 cal [calendar] yr)? (
http://geology.geoscienceworld.org/cgi/content/abstract/35/7/667 and
http://cbe.wisc.edu/assets/docs/pdf/srp-bio/LucasSrevised.pdf)?


Can the sediments of a any single lake be considered representative of all
lakes across the North American continent?

Can the presence or absence of a fungus spores in a single lake's 14,000 yr
old sediments be solely attributable to a diverse group of fauna, ranging
from slow moving sloths, large runimant herbivores, large non-ruminant
herbivores, large predators, and smaller cousins of all of the
aforementioned families of animals?
Can a single study on a single lake be expected to control all of the
limnologic variables, geological variables, and microbial variables that
affect depth and survivability of fungus spores, particularly when that lake
had been scraped (multiple times?) and filled by glacial activity after the
deposition of the lake sediments?   Question: What if the megafauna died
only in that singular region?  Are there reliable studies that show that
lakes of this type and temperature consistently have no key fungal spores,
only when there were no corresponding populations of mega fauna of the
period?  Does the absence of fungal spores always spell the extermination of
megafauna (i.e in the NY public Library)?

Should data that are constrained by the issues listed above be considered as
useful in drawing conclusions about timing, let alone the cause(s) of
proposed disappearances of mega fauna from all major populations from the
entire range of Central America to Northern Canada?

This is a nice first study that takes a snapshot of one intersting locale
that is a small part of a very divese whole.
-- 
Sid Hollander
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