Posted on 07/31/2003 10:26:50 AM PDT by balrog666
By analysing masses of data from fossils throughout the world, a group of palaeontologists hopes to address the big questions about the history of life on Earth. Quirin Schiermeier logs on to the Paleobiology Database.
We've never had it so good — or at least that has been the prevailing view among palaeobiologists who have tried to track the history of our planet's biodiversity. On the long road from the first stirrings of multicellular life to today's shimmering diversity, untold numbers of species have fallen by the wayside. From time to time, legions of creatures have perished together in mysterious mass extinctions. But if you examine the fossil record, the evolution of new species seems generally to have had the upper hand over extinction. Like stock indices in a bull market, plots showing the diversity of life over geological time reveal a rising trend, despite occasional setbacks.
But how can we be sure that this isn't a sampling artefact? Even high-school biology students are taught that the fossil record is far from complete. Given that younger rocks are more likely to be exposed at the surface, it is possible that the apparent rise in biodiversity merely represents the greater scrutiny that has been applied to these strata. Palaeontologists have even coined a term for this source of bias: 'the pull of the recent'. Add in the confusion caused by the varied names used to describe the same organisms, and some researchers argue that attempting to assess the history of Earth's biodiversity is a fool's quest.
(Excerpt) Read more at nature.com ...
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