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Re: Supernova link to Rancholabrean fauna extinction?



On Fri, Jul 22nd, 2011 at 2:00 PM, "Thomas R. Holtz, Jr." <tholtz@umd.edu> 
wrote:

> The lengths that people will go to in order to say "it was anything but
> humans"...
> 
> This despite the great asynchrony of extinctions around the world, but
> their close association with human arrivals; the fact that unlike all
> other mass extinctions these are exclusively terrestrial macrofauna; etc.

Although it does make you wonder why humans chose to colonise new areas at 
those specific 
times. Could they not have been 'climate refugees' forced to seek out new 
territories? Any sudden 
climatic changes would after all have affected humans as much as any other 
species - and a 
sudden influx of spear-happy hominids at the same time as local species were 
under climate-
induced stress may have been more likely to cause extinctions than either of 
those pressures 
acting alone.

As far as the terrestrial extinctions are concerned; if supernova events were 
reducing O3 
coverage, then living underwater may have helped reduce the effects of an 
increase in UV 
penetration (as would being a nocturnal burrowing creature, for that matter).

> 
> On Thu, July 21, 2011 10:18 pm, bh480@scn.org wrote:
> > From: Ben Creisler
> > bh480@scn.org
> >
> > OK...this is not about dinosaurs, but it may interest people anyway. At
> > least it might inspire some paleoartists...
> >
> >
> > G. Robert Brakenridge (2011)
> > Core-collapse Supernovae and The Younger Dryas/Terminal Rancholabrean
> > Extinctions.
> > Icarus (advance online publication)
> > doi:10.1016/j.icarus.2011.06.043
> > http://www.sciencedirect.com/science/article/pii/S0019103511002612
> >
> > Abstract
> > Early predictions that some supernovae release large quantities of prompt
> > high energy photons are now corroborated by optical identification of
> > core-collapse supernovae associated with extragalactic GRBS (beamed
> > gamma-ray bursts) and XRFS (beamed or unbeamed x-ray flashes). Given the
> > in-galaxy supernova frequency and GRB and XRF recurrence statistics,
> > significant Earth-incident events during the past several million years
> > very likely occurred and nearby events should have affected the Earth and
> > other planetary atmospheres, including terrestrial surface solar UV, the
> > Earth?s climate, and its ecology. The Younger Dryas Stadial (12,900 to
> > 11,550 calendar yr BP) began with sharply cooler temperatures in the
> > Earth?s northern hemisphere, regional drought, paleoecological evidence
> > compatible with increased UV, and abrupt increases in cosmogenic 14C and
> > 10Be in ice and marine cores and tree rings. In North America,
> > stratigraphic and faunal sequences indicate that a major pulse of
> > mammalian
> > extinctions (at least 23-31 genera) began very close to 12,830 calendar yr
> > BP and was sudden: deposits one century younger are devoid of diverse
> > extinct fauna remains. A 10 second beamed GRB within 2 kpc of the Earth
> > delivers 100 kJ m-2 fluence to the Earth?s atmosphere, where it causes
> > spallation and catalytic reactions depleting 35-50% O3, and producing
> > excess NOx species (which favor cooling, drought, and surface fertility),
> > 14C, and 10Be. An un-beamed, 1050 erg hard photon impulse at  250 pc
> > produces similar terrestrial atmospheric effects. A well-characterized
> > massive star supernova, the unusually close Vela event (d = 250 ± 30 pc;
> > total energy of 1-2 x 1051 erg; age constrained from remnant nebula shock
> > velocities considerations at 13,000-16,000 yr and from the pulsar
> > characteristic age at 11,400 yr) may have initiated the Younger Dryas
> > climate change, and caused the extinction of the terminal Rancholabrean
> > fauna.
> >
> >
> >
> > --------------------------------------------------------------------
> > mail2web - Check your email from the web at
> > http://link.mail2web.com/mail2web
> >
> >
> >
> 
> 
> Thomas R. Holtz, Jr.
> Email: tholtz@umd.edu Phone: 301-405-4084
> Office: Centreville 1216
> Senior Lecturer, Vertebrate Paleontology
> Dept. of Geology, University of Maryland
> http://www.geol.umd.edu/~tholtz/
> Fax: 301-314-9661
> 
> Faculty Director, Science & Global Change Program, College Park Scholars
> http://www.geol.umd.edu/sgc
> Fax: 301-314-9843
> 
> Mailing Address:      Thomas R. Holtz, Jr.
>                       Department of Geology
>                       Building 237, Room 1117
>                       University of Maryland
>                       College Park, MD 20742 USA
> 
> 
> 


-- 
_____________________________________________________________

Dann Pigdon
Spatial Data Analyst               Australian Dinosaurs
Melbourne, Australia               http://home.alphalink.com.au/~dannj
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