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Despite all the hype, the link between a bolide impact and the extinction
of the dinosaurs is not proven. As Cretaceous-Tertiary Mass Extinctions edited
by Norman McLeod and Gerta Keller (W. W. Norton, £40, ISBN 0 393 96657 7)
shows, even 16 years of extensive research has failed to prove a causal link
between the undoubted impact event and undoubted contemporaneous mass
extinctions of certain organisms.