Re: Endothermy speculation

["Thomas R. Holtz, Jr." <th81@umail.umd.edu>]

At 12:22 PM 7/14/99 PDT, Matt Bonnan wrote:

Matt's summary was an excellent one.  However, one thing that should be
emphasized:

>This is a bit more sticky, since we cannot test dinosaurs directly for ecto- 
>or endothermy.  We do know that the Mesozoic climate tended to be warmer 
>than the present (in fact, we know of no glacial depositis or evidence of 
>ice caps during this time), but we do find dinosaurs distributed worldwide, 
>and some within the Antarctic circle, which at the very least would have 
>been six months of darkness followed by six months of light.

There was no "Mesozoic climate" as such.  The Mesozoic is more than twice as
long as the Cenozoic, and includes periods of both extreme continental
emergence (for example, much of the Triassic) as well as the times of the
most extreme continental flooding post-Pangaea (and among the greatest
continental flooding known in the past 544 million years).  On average it
appears that temperatures were warmer than found in the Holocene, and
probably warmer than found in most of the later Cenozoic.  However, there
were a variety of different climate types and distribution during the long
duration of the Mesozoic.

                        Thomas R. Holtz, Jr.
                        Vertebrate Paleontologist
Deptartment of Geology                  Director, Earth, Life & Time Program
University of Maryland                  College Park Scholars
College Park, MD  20742       
Webpage: http://www.geol.umd.edu        Phone:301-405-4084
Email:tholtz@geol.umd.edu               Fax:  301-314-9661