Taphonomic effects and preserved overgrowth relationships among encrusting marine organisms

Overgrowth relationships in the fossil record of encrusting organisms on marine hard substrata have been used to infer success in competitive interactions, particularly for modular organisms such as colonial invertebrates and coralline algae. However, this interpretation has been questioned to varying extent--even by those who have used the procedure--because of the possibility that any individual observation may represent growth over a senescent organism or dead skeletal remains. Where sufficient numbers of overgrowth relationships are available to demonstrate that the proportions of overgrowths between two modular taxa are not essentially equal, the competitive superiority of the more frequently overgrowing taxon should be accepted. The degree of success of the more frequently overgrowing taxon was at least as great as seen in the fossil record and was probably substantially greater, depending upon the percent of bare surface on the substratum.