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Re: Some data (was Re: Herbivore protection)



In a message dated 97-05-28 20:51:05 EDT, th81@umail.umd.edu (Thomas R.
Holtz, Jr.) writes:

Thank you for the valuable input.
Carolyn

<< 
 Depending on the method used, the ratio of tyrannosaurids to all
 ornithischians (hadrosaurids and ceratopsids, predominantly) range from 1:5
 (well within the ectothermic predator:prey ratios) to 1:511 (which would be
 very low even for an endothermic predator:prey ratio).  Here are some the
 results (taken from Farlow, J.O. 1993.  On the rareness of big, fierce
 animals: speculations about the body sizes, population densities, and
 geographic ranges of predatory mammals and large carnivorous dinosaurs.
 American Journal of Science 293-A:167-199).
 
 (the orignial papers for the data can be found in the text of the article).
 
 1:10-1:13  Judith River Group, based on articulated specimens.
 1:5-1:6  Judith River Group, based on surface collected isolated scrap.
 1:23  Hell Creek Formation, based on surface collected isolated scrap.
 1:22-1:511 (mean 1:115) Judith River Group, based on screen washed samples.
 
 Thus, there does not seem to be a "disproportionately low fossil
 representation" of tyrannosaurids at all. >>