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RE: mosasaur babies/no marine dinos
At 09:13 PM 02/01/02 -0500, John Bois wrote:
This falsifies the equatorial barrier hypothesis.
Not at all, as has been pointed out - the equator is not an actual barrier,
of course! More to the point might be the observation that the equatorial
range of the Galapagos Penguin is still separated by a vast gap from the
most southerly of the Pacific Auks, Craveri's Murrelet of the Gulf of
California. Apparently the waters in between are not ideal habitat for
either group. In the Atlantic, the gap between the southernmost alcid and
the northernmost penguin is far greater; even non-breeding penguins rarely
get farther north than southern Brazil.
But not a polar continental land mass free of mammals. A relationship
exists between the area of a land mass and the diversity of its
species. Penguins are diverse, auks not--was this the case always? Are
you suggesting that auks were as specialized/derived as penguins?
Actually, I would disagree about the diversity comment. Considering living
(or, in the case of the Great Auk, historically extinct) species only,
there are 17 species of penguins in six genera and 24 species of auks in 12
genera, so auks are actually more diverse than penguins.
Secondly, only three of the 17 species of penguins nest on "a polar
continental land mass free of mammals", and of these one, the Chinstrap, is
only a local breeder on the Palmer Peninsula. This is actually fewer than
the four species that nest on continental land masses with land-based
mammalian predators - the Magellanic and Humboldt in South America, the
Black-footed in Africa and the Blue in Australia (not to mention introduced
predators on new Zealand, where three species nest on the main islands, and
the species nesting on the Falklands, which had an endemic species of canid
until it was exterminated in the 19th century).
Ronald I. Orenstein Phone: (905) 820-7886
International Wildlife Coalition Fax/Modem: (905) 569-0116
1825 Shady Creek Court
Mississauga, Ontario, Canada L5L 3W2 mailto:firstname.lastname@example.org