car park.
E. Alroy has also used the database to reassess the accuracy of species names. His findings
suggest that irregularities in classification inflate the overall number of species in the fossil
record by between 32 and 44 per cent. Single species often end up with several names, he
says, due to misidentification or poor communication between taxonomists in different
countries. Repetition like this can distort diversity curves. “If you have really bad taxonomy in
one short interval, it will look like a diversity spike—a big diversification followed by a big
extinction-when all that has happened is a change in the quality of names,” says Alroy. For
example, his statistical analysis indicates that of the 4861 North American fossil mammal
species catalogued in the database, between 24 and 31 per cent will eventually prove to be
duplicates.
F. Of course, the fossil record is undeniably patchy. Some places and times have left behind
more fossil-filled rocks than others. Some have been sampled more thoroughly. And certain
kinds of creatures—those with hard parts that lived in oceans, for example–are more likely to
leave a record behind, while others, like jellyfish, will always remain a mystery. Alroy has also
tried to account for this. He estimates, for example, that only 41 per cent of North American
mammals that have ever lived are known from fossils, and he suspects that a similar proportion
of fossils are missing from other groups, such as fungi and insects.
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