Re: [paleo_bio_dinosaur_ontology] dinosaur skeletal anatomy

[Mike Taylor <mike@indexdata.com>]

> Date: Tue, 28 Oct 2003 16:36:52 +0100
> From: "David Marjanovic" <david.marjanovic@gmx.at>
> 
>> Yes, that's ".0001%" and "million"! Most likely these words are
>> from a catalogue editor and not Steve Parker (of NHM in London),
>> but the figures sound to me so astoundingly absurd. Any comments?
> 
> It may well be correct, although it's quite a high estimate.

Quite.

Peter Dodson addresses this a 1990 paper, and reaches the conclusion
that there were probably a total of 900-1200 dinosaur genera
throughout the Mesozoic (though I confess I that don't fully follow
his reasoning).  The paper is

        Dodson, Peter (1990).  Counting Dinosaurs: How many
        kinds were there?  Proc. Natl. Acad. Sci., vol 87,
        pp. 7608-7612; October 1990

and it is freely available for download at
        http://www.pnas.org/cgi/reprint/87/19/7608.pdf

Abstract

        Dinosaurs figure prominently in discussions of mass
        extinctions and evolutionary metrics, but their
        usefulness is hampered by archaic taxonomy, imprecise
        biostratigraphy, and imperfect preservation that bias
        our understanding of dinosaur diversity. A critical
        evaluation shows that of 540 genera and 800 species of
        dinosaurs proposed since 1824, 285 genera and 336
        species are probably valid. Nearly half of all genera
        are based on a single specimen, and complete skulls
        and skeletons are known for only 20% of all
        dinosaurs. Dinosaurs are known from every
        continent. Countries with the greatest known diversity
        of dinosaurs are (in descending order) the United
        States, Mongolia, China, Canada, England, and
        Argentina; the greatest future increases may be
        expected from Argentina and China. Nearly half of all
        dinosaur genera are of latest Cretaceous age
        (Campanian or Maastrichtian). Estimates of the average
        duration of a dinosaur genus range from 5 million to
        10.5 million years, with the most likely value about
        7.7 million years. Dinosaurs evolved as rapidly as
        Cenozoic mammals. Global dinosaur diversity during the
        Campanian and Maastrichtian is estimated at 100 genera
        per stage, using a logistic model to estimate future
        discoveries. A model of increasing diversity and a
        bottleneck model compensate for the biases in the
        preserved fossil record. The number of dinosaurs that
        have ever lived is estimated at 900-1200 genera. The
        fossil record of dinosaurs is presently about 25%
        complete. Dinosaurs disappeared in the Maastrichtian
        near the peak of their historic diversity.

There was a follow-up in 1997 which I've not yet seen:

        Holmes, T. and Dodson, P. (1997) Counting More
        Dinosaurs--How Many Kinds Are There; Dinofest
        International: Proceedings of a Symposium Held at
        Arizona State University (editors D. Wohlberg,
        E. Stump, G. Rosenberg), pp. 125-128

I don't know if he revised the figure upwards in that paper ... but I
am guessing that he didn't go as high as the millions that other
article suggested!

 _/|_    _______________________________________________________________
/o ) \/  Mike Taylor  <mike@indexdata.com>  http://www.miketaylor.org.uk
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