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Re: "No Bolides!"
No one is saying that the comet/meteor itself killed off the dinosaurs and
~75% of thier contemporaries. There is a confirmed crater in the Yucatan that
is nearly 300Km in diameter. There was probably no Singular mechanism but a
chain of events. But an ecologcal disaster that may have resulted in the
collapse of the food web seems to have been the trigger for the mass
extinctions. When the impact occured 65Ma the area was a warm , shallow
(<300 m) carbonate platform and tremendous volumes of CO2 were released,
billions of gallons of sea water vaporized, flash fires ignited thousands of
miles away form ballistic emplacement of fallout and global ranging tsunamis
than may have been as high as 2Km all would have had immediate effect on the
biota! Longer term climatic phenomena may have ranged from a super Greenhouse
, to a so called "nuclear winter" scenario, acid rains, etc. Massive off-the
scale earthquakes would probaly continue for centuries (meg-aftershocks).
Ecosystems would be hard pressed to withstand this stress and it would be
inevitable that die offs would ensue. Along with the dinosaurs, I believe it
was Raup who stated that no land animal over 25Kg survived the event.
Placental mammals were very hard hit, so were numerous marine ceatures, i.e.
Ammonites, rudists clams, tropical reefs corals, mosasaurs, pterosaurs all
became extinct. Zooplankton was hard hit as well , and land plants were
Besides, many of the above taxa such as the dinosaurs and ammonites were
doing well beforet the catastrophe and then suddenly disappeared. In all
likelyhood, _yes_ it was a bolide that started it all!
Thomas R. Lipka