Re: The Biggest Dinosaurs

[John Bois <jbois@umd5.umd.edu>]

On Wed, 20 Aug 1997, Thomas R. Holtz, Jr. wrote:

> In fact, during the last eleven million years or so of the Cretaceous of
> western North America, there seems to be a net size increase in most of the
> dinosaur groups.  The latest Maastrichtian tyrannosaurids, ceratopsians,
> pachycephalosaurians, "hypsilophodontians", ankylosaurids, and nodosaurids
> are the biggest known for each of those lineages.  Furthermore, the average
> hadrosaurids of the latest Maastricthian are pretty big, too, but the
> largest known are from either the early Campanian of Baja California or the
> early Maastrichtian of China.

Are there any best-guesses as to why this mean size increase
occurred?  Was there a similar size increase among smaller dinosaurs of
the same time?
Thanks in advance.
John Bois.