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On Jan 9, Greg Paul wrote:

>The constantly moving reptiles mentioned above move VERY SLOWLY, at well
>under 1 km/h. This is because their typically pathetic aerobic exercise
>metabolism cannot sustain higher walking speeds.

        This is generally true, but there are exceptions.  Some varanid,
teiid, agamid and helodermatid lizards can sustain aerobic speeds of 
1 km/h or more.  The elite endurance champion of lizards to date is the 
teiid _Cnemidophorus tigris_.  Garland (1993) reports a mean maximal 
aerobic speed ([MAS] the speed at which Vo2 max is reached) of 1.46 km/h,
and some particularly athletic specimens could sustain a MAS of 2.3 km/h,
not bad for a 20 gram lizard!  In fact, the latter speed overlaps 
published MAS for some similarly sized mammals (Garland, Geiser &
Baudinette, 1988).

        Garland, T. Jr. (1993).  Locomotor performance and activity 
metabolism of _Cnemidophorus tigris_ in relation to natural behaviors.
_in_ Biology of Whiptail lizards (Genus _Cnemidophorus_), J. W. Wright &
L. J. Vitt, (Eds).  Oklahoma Museum of Natural History, Norman.
        Garland, T. Jr., Geiser, F., & Baudinette, R.V. (1988).  
Comparative locomotor performance of marsupial and placental mammals.
Journal of Zoology, 215, 505-522.

Guy Leahy
Dept. of PEHR
Western  Washington University
Bellingham, WA 98225