Dinosaur Diversity and the Rock Record

Barrett, P.M., McGowan, A.J., and V. Page. 2009. Dinosaur diversity and the rock record. Procedings of the Royal Society B published online 29 April 2009. doi: 10.1098/rspb.2009.0352

Abstract - Palaeobiodiversity analysis underpins macroevolutionary investigations, allowing identification of mass extinctions and adaptive radiations. However, recent large-scale studies on marine invertebrates indicate that geological factors play a central role in moulding the shape of diversity curves and imply that many features of such curves represent sampling artefacts, rather than genuine evolutionary events. In order to test whether similar biases affect diversity estimates for terrestrial taxa, we compiled genus-richness estimates for three Mesozoic dinosaur clades (Ornithischia, Sauropodomorpha and Theropoda). Linear models of expected genus richness were constructed for each clade, using the number of dinosaur-bearing formations available through time as a proxy for the amount of fossiliferous rock outcrop. Modelled diversity estimates were then compared with observed patterns. Strong statistically robust correlations demonstrate that almost all aspects of ornithischian and theropod diversity curves can be explained by geological megabiases, whereas the sauropodomorph record diverges from modelled predictions and may be a stronger contender for identifying evolutionary signals. In contrast to other recent studies, we identify a marked decline in dinosaur genus richness during the closing stages of the Cretaceous Period, indicating that the clade decreased in diversity for several million years prior to the final extinction of non-avian dinosaurs at the Cretaceous-Palaeocene boundary.


  1. *hand shoots up*

    If they blame sampling bias on the lack of theropod and ornithischian material, why don't they attribute sampling bias to the close of the Cretaceous in terms of dinosaurian diversity? Is it because sauropods were still going strong? Isn't that, in itself, a sampling bias?

    Or am I totally misunderstanding the point here?

  2. Neeeeeeeeeeeeeed Paper.

    Neeeeeeeeeeeeeeeeed Paper!

  3. The cae for a decline in diversity has been made for many years. Colbert argued for it, and Bakker believed it. Some researchers have challenged it but only on the basis of Hell Creek sampling, whereas most of the decline is thought to have already occurred by then.


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