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Re: Extinction credit due
Numerous contributors have recently credited Alvarez, et al., 1980 as the
first to propose dinosaur extinction by impact of a large bolide.
In 1956 M. W. De Laubenfels proposed that the extinction of dinosaurs was
caused by heat and incandescent material from the impact of a large meteorite
or planetesimal (Journal of Paleontology, Vol. 30, p. 207-212). He calculated
that a large object would completely vaporize on impact. His evidence for such
an impacting object was simple and more conclusive than the presence of
iridium. He simply noted the presence of impact craters on the earth and
discussed the effects of the 1908 Tunguska event. De Laubenfels was not aware
of any crater that might closely compare in age to the K/T extinction, but then
again neither did Alvarez, el al. in 1980.
Why do Alvarez, et al. receive the credit for being the "first" to propose
bolide extinction and, to my knowledge, why has De Laubenfels never received
any mention? I suspect that Alvarez, et al. ran samples through a machine that
spewed forth "hard" results. We tend to believe machines and numbers derived
through calculations, sometimes perhaps too quickly. At any rate, De
Laubenfels had evidence for impact that today should be considered as
convincing for impact as did Alvarez, et al., even if he could not associate an
impact crater directly with the timing of extinction.