Quantifying Seafood Through Time: Counting Calories in the Fossil Record

Abstract

Energy and nutrients are the fundamental currencies of ecology and changes in energy and nutrient availability are thought to have played an important role in the long-term development of marine ecosystems. However, meaningfully quantifying when, where, and how such changes have occurred has been a difficult and longstanding problem. Here, some of the various lines of evidence that have been brought to bear on this issue in the past two decades are reviewed, particularly those based on the fossil record of benthic invertebrates. This paper focuses on abundance, body size, and metabolism, three distinct but closely interrelated aspects of ecosystem structure that control (or are controlled by) energy fluxes. Each of these is subject to biases and inherent uncertainties that present significant challenges for making inferences from the fossil record, but when carefully controlling for environmental, taphonomic, and methodological variations there are robust trends that can be discerned above the noise. Integrating these different types of data in a single quantitative framework presents additional complications, but coherent patterns emerge from some such analyses. Accurate quantification of energetic trends in the fossil record is difficult but is a worthwhile goal because of its potential to illuminate the energetic dimension of major diversifications, extinctions, and secular ecological-evolutionary trends and link them more directly to their Earth Systems context.