Remember all the media hype last year about Ida, the “missing link” that bridged the gap between humans and lemurs? Only it didn’t. A new paper from the palaeobiology department at the University of Bristol provides a useful corrective to the sensationalistic and overblown claims about fossils that “rewrite evolutionary history”:
Is evolutionary history repeatedly rewritten in light of new fossil discoveries?
Mass media and popular science journals commonly report that new fossil discoveries have ‘rewritten evolutionary history’. Is this merely journalistic hyperbole or is our sampling of systematic diversity so limited that attempts to derive evolutionary history from these datasets are premature? We use two exemplars—catarrhine primates (Old World monkeys and apes) and non-avian dinosaurs—to investigate how the maturity of datasets can be assessed. Both groups have been intensively studied over the past 200 years and so should represent pinnacles in our knowledge of vertebrate systematic diversity. We test the maturity of these datasets by assessing the completeness of their fossil records, their susceptibility to changes in macroevolutionary hypotheses and the balance of their phylogenies through study time. Catarrhines have shown prolonged stability, with discoveries of new species being evenly distributed across the phylogeny, and thus have had little impact on our understanding of their fossil record, diversification and evolution. The reverse is true for dinosaurs, where the addition of new species has been non-random and, consequentially, their fossil record, tree shape and our understanding of their diversification is rapidly changing. The conclusions derived from these analyses are relevant more generally: the maturity of systematic datasets can and should be assessed before they are exploited to derive grand macroevolutionary hypotheses.
So what a surprise: the actual situation is much more complex than the headlines suggest. It’s worth taking a look at the full text of the paper, which, for the time being, can be downloaded free at the journal website:
Tarver J. E., Donoghue P. C. J., Benton M. J. 2010. Is evolutionary history repeatedly rewritten in light of new fossil discoveries? Proceedings of the Royal Society B, Published online before print September 1, 2010, doi: 10.1098/rspb.2010.0663