Chance News 21

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The next two Forsooths are from the October RRS NEWS.


16 March 2006

Times on line

20 March 2006

Estimating the diversity of dinosaurs

Proceedings of the National Academy of Sciences (, Published online before print September 5, 2006 Steve C. Wang, and Peter Dodson

Fossil hunters told: Dig deeper ( Philadelphia Inquirer, September 5, 2006 Tom Avril

Steve Wang is a statistician at Swarthmore College and Peter Dodson is a Penn paleontologist at the University of Pennsylvania. This study was widely reported in the media.

In their paper the authors provided the following description of their results. Here are a few definitions that might be helpful: genera: a collective term used to incorporate like-species into one group,nonavian: not derived from birds, fossiliferous: containing a fossil, rock outcrop: the part of a rock formation that appears above the surface of the surrounding land

Despite current interest in estimating the diversity of fossil and extant groups, little effort has been devoted to estimating the diversity of dinosaurs. Here we estimate the diversity of nonavian dinosaurs at 1,850 genera, including those that remain to be discovered. With 527 genera currently described, at least 71% of dinosaur genera thus remain unknown. Although known diversity declined in the last stage of the Cretaceous, estimated diversity was steady, suggesting that dinosaurs as a whole were not in decline in the 10 million years before their ultimate extinction. We also show that known diversity is biased by the availability of .. Finally, by using a logistic model, we predict that 75% of discoverable genera will be known within 60-100 years and 90% within 100-140 years. Because of nonrandom factors affecting the process of fossil discovery (which preclude the possibility of computing realistic confidence bounds), our estimate of diversity is likely to be a lower bound.

To be continued