Large body size in movie monsters has inspired a new generation of scientists to explore the fact that real animals, both extinct and extant, have attained almost comparable sizes throughout geologic time. In this study I look at gigantism as preserved in the fossil record and at biologic problems arising from attaining a large size. Cope’s Rule states that there is a trend through geologic time for organisms in a lineage to attain larger body sizes. Many researchers debate whether this is, in fact, a “rule” or merely an observable trend based upon other factors. It is true that the largest organisms have become larger over time, but the smallest organisms have also remained just as small. Additionally, the effect of mass extinctions on weeding out the largest organisms allows the smaller surviving organisms to fill vacant ecological niches. This, in turn, allows the smaller organisms to attain larger body sizes to fill these niches which, in effect, increases their average body size. My study is predominately a review of the literature on large body size; however, I also conducted independent research in which I took raw data from the Paleobiology Database on recorded specimen sizes and determined that large body size is a visible trend throughout geologic time; smallest in the Cambrian and largest in the Holocene. I conclude that large organisms, though perhaps smaller than their movie monster counterparts, have existed throughout geologic time and have attained truly massive body sizes.
William Rood, ’12
Sponsor: Benjamin Greenstein