Acta Zoologica Cracoviensia, 39(1) 1996
Issue:
VOL 39(1) 1996
Keywords:
Hutchinsonian ratios, body mass, competition, Quaternary mammals, guild, community evolution, biodiversity
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Tracking mammal body size distributions in the fossil record: a preliminary test of the ‘rule of limiting similarity’
Abstract:
Ecologists have puzzled for years over the distributions of body sizes in organismal communities. G. E. Hutchinson (1959) suggested the spacing of body sizes among guild members might serve to reduce competition for resources. He proposed that a ratio of at least 1.3 between average linear dimensions of trophic parts or some other measure in potential competitors would indicate appropriate distance. This ratio would translate to 2.0, or a doubling, when body mass is used as a proxy. These “Hutchinsonian ratios” have been explained by other investigators as statistical anomalies. This study proposes methods, based on the accurate estimation of body mass in extinct species, to track the evolution of body size distributions in mammalian communities. Preliminary data and resulting size ratios from the Fox Canyon local fauna of the Meade Basin in Kansas do not conform to expectations under the rule of limiting similarity.
