The biology of fossil abundance

Abstract

Many patterns of fossil abundance are very similar to abundance patterns of living species. Examples include: body size abundance, geographic range distributions, community abundance, paleoenvironmental patterns and abundance, greater temporal and spatial abundance variation in rare species than in common species, correlation of abundance density and geographic range, and species-area curves as seen in "species-time" curves. These patterns are apparently preserved despite many known taphonomic biases because there must be some correlation between relative living and fossil abundance. Suggested reasons for this correlation include time-averaging, which accumulates even rare species through time, and the fact that most abundance patterns compare groups with relatively constant phylogenetic influences on depositional processes. The importance of abundance and rarity has been greatly overlooked in paleontology. The described fossil record is based mainly on the 6-7% most abundant and widespread species. Most of the widely discussed interpretations of past events, such as paleocommunity persistence and biosphere extinctions, are thus based on exceptionally abundant, broadly adapted species. Better understanding of the biological origins of fossil abundance can greatly improve the accuracy of our interpretations of past events.