Jeremy and I have given that question some thought in the paper below that may be of interest.

Pdf can be downloaded from link or by writing one of us an email.

best

Jeremy and Peter

jergold@stanford.edu / peter.madsen@bios.au.dk

The evolution of foraging capacity and gigantism in cetaceans

J. A. Goldbogen, P. T. Madsen

Journal of Experimental Biology  2018  221:  jeb166033  doi: 10.1242/jeb.166033  Published 12 June 2018

ABSTRACT

The extant diversity and rich fossil record of cetaceans provides an extraordinary evolutionary context for investigating the relationship between form, function and ecology. The transition from terrestrial to marine ecosystems is associated with a complex suite of morphological and physiological adaptations that were required for a fully aquatic mammalian life history. Two specific functional innovations that characterize the two great clades of cetaceans, echolocation in toothed whales (Odontoceti) and filter feeding in baleen whales (Mysticeti), provide a powerful comparative framework for integrative studies. Both clades exhibit gigantism in multiple species, but we posit that large body size may have evolved for different reasons and in response to different ecosystem conditions. Although these foraging adaptations have been studied using a combination of experimental and tagging studies, the precise functional drivers and consequences of morphological change within and among these lineages remain less understood. Future studies that focus at the interface of physiology, ecology and paleontology will help elucidate how cetaceans became the largest predators in aquatic ecosystems worldwide.

http://jeb.biologists.org/lookup/doi/10.1242/jeb.166033.