>Is extinction a scientific concept? I thought, at least under
Punk Eek, that a species just sort of fade until they are
resurrected into new forms, such as dinosaurs --> birds.<
No, punctuated equilibrium claims that species change
little for long periods of time and then rapidly either go
extinct or evolve into new species. Whether or not the
resulting for is a new species depends on the definition.
You are probably thinking of a slightly different issue.
Some advocates of a phylogentic species concept might
claim that either a species goes extinct entirely or else it
gives rise to two descendant species and the original
species becomes extinct. The fact that a descendant form
may be very different from the ancestor is ignored if no
other branches have arisen. For example, if you lump all
early Homo as Homo habilis, all intermediate Homo as H.
erectus, and all modern-looking ones as H. sapiens,
believing the course of evolution to have been roughly
linear through these, then the advocate of this view would
claim that you should call them all Homo sapiens because
no branches have arisen, despite the many differences in
morphology.
The polar bear arose from the brown bear in the past few
hundred thousand years or so. Modern brown bears seem
unchanged from the fossil brown bears before the split, yet
extreme advocates of this view would claim that either the
modern brown bears are a separate species from the
ancestral brown bears or else that the polar bear should
not be considered a separate species, even though it is so
morphologically specialized that it once was given its own
genus.
Dr. David Campbell
Old Seashells
46860 Hilton Dr #1113
Lexington Park MD 20653 USA
bivalve@mail.davidson.alumlink.com
That is Uncle Joe, taken in the masonic regalia of a Grand
Exalted Periwinkle of the Mystic Order of Whelks-P.G.
Wodehouse, Romance at Droigate Spa
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