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Re: Re[2]: Swimming mammoths and climate change



In a message dated 96-04-09 14:14:39 EDT, you write:

>Charcharodon charcharis is the great white, C. megalodon is the
>(Cretaceous?)

C. megalodon is a Miocene (23.7 -5.3 Ma according to the DNAG geologic Time
Scale of 1988)  beast that has been found in the famous Calvert Cliffs of
Marylnad, and other places along the east coast of the US. But I do remember
seeing a post on this list by a shark expert who, if I remember correctly,
refuted this for some reason. I'm sure if the shark subject lasts long enough
someone will delurk and set us straight ;-)

>Giant White (see the lovely silhouette at the Smithsonian, it's HUGE).

Don't remember seeing the silhouette (my meory must be fading) but the mount
of just the _jaws_ overhanging the staircase to the giiftshop was impressive.

>I recall reading in a book aimed at young adults (gotta keep the
>reading skills up) an illustration of a herd of elephants crossing a
>river, snorkeling with their trunks.  I think they can swim pretty
>fast too.  The herd (pod?) of swimmers might be less vulnerable to
>attack, although I'm not sure how often great whites attack large
>prey (orcas, on the other hand, will

I have seen shows with elephants crossing rivers with just their trunks above
water but there are no sharks or comparable predators to worry about there
except maybe a large croc. But scale up your body of water to the size of an
ocean strait with its strong currents and very capable large predators and I
think you will see what I mean. To me it just don't add up and 26 miles of
swimming?!

>take on larger animals in packs).  The problem does develop,
>however, when a feeding frenzy starts and the pachyderms are far
>from shore.  Of course, it only takes a few herds to populate an
>island.

Ok. Let's say that one or two individuals from each heard make it to
Catalina. They probably are genetically related and or of the same
sex. The next problem is the _gene_pool_. Very early on interbreeding
will take place leading to often fatal mutations and unviable
offspring.  Sounds like a dead end to me! IMHO

In summary the factors aginst are;
1)To far to swim  (26 miles)
2)Ocean Currents and maritime weather
3)Sharks and Orcas who's feeding frenzies would take out the entire lumbering
lot
4)Very low survival assuming any reached at all
5)Inevitable interbreeding leading to genetic mutation, sterility and
extinction!

I still favor some yet to be discovered land bridge. Maybe some paleotctonic
simulations could be run to see if there were some platform, island chain or
some other feature could have provided the means. Just slide the two plates
backwards about 10,000years and start form there.

Regards,
Thomas R. Lipka
Paleontological/Geological Studies