Re: Rugops: some questions

[Mike Taylor <mike@indexdata.com>]

> Date: Tue, 08 Jun 2004 09:14:53 -0400
> From: "Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>
> 
> Several different hypotheses have been put forth with regards to
> which parts of Gondwana divided first.
> [...]
> However, as discussed in a different thread current on the list, our
> temporal and geographic coverage of the Mesozoic terrestrial world
> isn't particularly good. Therefore, the lack of structure may have
> as much to do with out lack of knowledge from large parts of the
> appropriate regions and times than from the near-simultaneous
> breakup of Gondwana.

For anyone who's interested in this and hasn't already read it, I'd
like to recommend

        Upchurch, Paul, Craig A. Hunn and David B. Norman.  2002.  An
        analysis of dinosaurian biogeography: evidence for the
        existence of vicariance and dispersal patterns caused by
        geological events.  Proceedings of the Royal Society of London
        B 269:613-621.  DOI 10.1098/rspb.2001.1921

which, among its other virtues, has this to recommend it: the PDF is
freely available on-line.  Go to
        http://dx.doi.org/
Enter the DOI from the reference above and hit the "Go" button.

Here's the abstract:

        As the supercontinent Pangaea fragmented during the
        Mesozoic era, dinosaur faunas were divided into
        isolated populations living on separate continents. It
        has been predicted, therefore, that dinosaur
        distributions should display a branching
        ('vicariance') pattern that corresponds with the
        sequence and timing of continental break-up. Several
        recent studies, however, minimize the importance of
        plate tectonics and instead suggest that dispersal and
        regional extinction were the main controls on dinosaur
        biogeography. Here, in order to test the vicariance
        hypothesis, we apply a cladistic biogeographical
        method to a large dataset on dinosaur relationships
        and distributions. We also introduce a methodological
        refinement termed 'time-slicing', which is shown to be
        a key step in the detection of ancient biogeographical
        patterns. These analyses reveal biogeographical
        patterns that closely correlate with
        palaeogeography. The results provide the first
        statistically robust evidence that, from Middle
        Jurassic to mid-Cretaceous times, tectonic events had
        a major role in determining where and when particular
        dinosaur groups flourished. The fact that evolutionary
        trees for extinct organisms preserve such distribution
        patterns opens up a new and fruitful direction for
        palaeobiogeographical research.

 _/|_    _______________________________________________________________
/o ) \/  Mike Taylor  <mike@indexdata.com>  http://www.miketaylor.org.uk
)_v__/\  "Never begin a sentence with 'and,' 'or,' or 'but,' and
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