>On Sun, 15 Feb 2004 09:24:10 -0500 [log in to unmask] writes:
>>  Dear Andrew and Ross;-
>>     Common in Florida fossil beds is a sinistral cone. Could that
>>  extinction have had anything to do with the glacial ages? If so,
>>  would global warming (or cooling) be an endangerment to other living
>>  species?
>>      Art
>
>Art,
>Periods of cooling (ice-ages) have definitely disrupted the environment
>enough to cause extinctions as the sea water (locked  up as ice)
>retreated, dropping the sea level and exposed large areas of what was
>shallow water.  Warming generally expands the coastal areas and creates
>new environments that can support new species.  Species adapted to cooler
>waters must retreat toward the poles to stay alive.  When southern
>Florida is totally flooded again, new species will start to evolve there.
>Will civilization survive well enough for our species to care?

Climatic swings are always going on, as the fossil record shows us...
so any apparent present warming should be no surprise.

Generally relatively mild warmings cause species distributions to
expand (tropicl/subtropical) and contract (boreal/temperate). Mild
coolings do the opposite. Local fossil records will record
accordingly LOCAL extinctions... these species generally live on
elsewhere.

Extreme coolings of course often cause extinctions... sometimes bad
ones; a notable cooling caused large-scale extinctions at the close
of the warm Eocene, about 37my ago, and is prominent in the fossil
record; the followinf Oligocene remained cool until the late part of
the period, when warm temperatures returned.

Conus adversarius seems to have become terminally extinct (that's not
hyperbole) in the early Pleistocene. This could well coincide with
the Pleistocene cooling, though I am not sure that Florida was cool
enough at any stage to cause extinction of warmwater taxa;
extinctions go on all the time, often without obvious causes.
--
Andrew Grebneff
Dunedin, New Zealand
64 (3) 473-8863
<[log in to unmask]>
Fossil preparator
Seashell, Macintosh & VW/Toyota van nut
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I want your sinistral gastropods!
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Opinions in this e-mail are my own, not those of my institution
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A: Because it reverses the logical flow of conversation.
Q: Why is top posting frowned upon?