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Re: Some data (was Re: Herbivore protection)
In a message dated 97-05-28 20:51:05 EDT, firstname.lastname@example.org (Thomas R.
Holtz, Jr.) writes:
Thank you for the valuable input.
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. >>