Bolides and Paleo. History

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So I see somebody out there isn't on Spring Break. It's about time someone
roused PaleoNet from its annual Spring slumber.

In response to Nathan Edel's comment on size and the K-T mass extinction,
large animals tend to be somewhat more specialized than their smaller
counterparts and so more prone to extinction by all mechanisms. The demise
of large animals (e.g., dinosaurs) is as consistent with the climatic
change model as it is with a bolide impact. I think what Mike Reese is
getting at is that the environmental damage predictions offered as
corollaries to the bolide impact hypothesis would seem to suggest that the
resulting extinctions should have been much more severe (from a taxic point
of view) than the available record seems to indicate. For example, today
local extinctions of fish, amphibians, and lepidosaurs (lizards and snakes)
are used as some our most sensitive ecological indicators of environmental
damage. Yet these groups seem to have suffered no substantial extinctions
through the Maastrichtian-Danian interval. You can argue, of course, that
the record of these groups is not as dense as we would like. It's not. Then
again, uppermost Maastrichtian dinosaurs are known (at best) from only a
handful of localities and (at worst) from only a single area in western
North America which (not coincidentally) is the same area from which our
best data on some of these "lower" vertebrate groups originates.

This recurring reference to extinctions as the hot paleo. topic of the day
is interesting all by itself. It's been more than a dozen years since
extinction studies more-or-less displaced punctuated equilibria-related
topics in many technical and popular articles. [Note: I am convinced that
the two debates are, at many fundamental levels, different faces of the
same philosophical disagreement.]  In reading the pre-1972 paleo.
literature I don't get the impression that paleo. in the '50's and '60's
was dominated by single issues in quite the same way. However, I must admit
that my entire paleo. career has been spent in the shadow of these two
controversies and so I may simply lack an appreciation for the detailed
history and significance of older paleo. controversies.  Did our science
change into somewhat of a "single issue" discipline in the '70's? If so,
why and has this been a good thing? If not, what were the burning questions
of previous times and did they burn as brightly in the technical and
popular literature?


Norm MacLeod



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Norman MacLeod
Senior Scientific Officer
N.MacLeod@nhm.ac.uk (Internet)
N.MacLeod@uk.ac.nhm (Janet)

Address: Dept. of Palaeontology, The Natural History Museum,
         Cromwell Road, London, SW7 5BD

Office Phone: 0171-938-9006
Dept. FAX:  0171-938-9277
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