concept

Pull of the Recent

A systematic bias described by David Raup: diversity in the fossil record appears to rise toward the present partly because older rock is progressively destroyed - subducted, metamorphosed, eroded - so the volume and exposed area of young rock is always greater. On top of that, modern biotas can be counted directly while ancient ones must wait on fossils. The result is that any diversity comparison through time tilts toward the recent unless corrected by subsampling methods.