Some of the biggest representatives of some phyla lived in the geological past, which are only barely touched upon here. We (Klug et al. 2014) recently tried to summarize the largest marine cephalopods and arthropods living in the Paleozoic: http://onlinelibrary.wiley.com/doi/10.1111/let.12104/full We pointed out the problems of verifying the largest specimens as well as taking into account geographic and intraspecic variation. Would your method also work to size oceanic giants in the geological past ? It would be great to integrating such data in a new study. More importantly, what do you think is the most important environmental factor driving body size in ocean giants ?