Blue Whales, Giants of the Deep, Were Not Always so Giant

A new study has examined the Baleen fossil record and discovered that whales were small for most of their evolutionary existence. In fact, whales have only become giants of the past three million years. Nick Pyenson of Smithsonian's National Museum of Natural History, Graham Slater from the University of Chicago and Jeremy Goldbogen from Stanford's Hopkins Marine Station have published their recent findings in the Proceedings of the Royal Society B.

Their analyses are based upon the Smithsonian’s collection of whale skulls, which are a good overall indicator of body size in whales. Fitting phylogenetic models with the estimated lengths of 63 extinct species and that of extant modern whales, they discovered gigantism was a more recent phenomenon during the Plio-pleistocene and it arose separately within different whale lineages.

With the appearance of the giants, came the loss/extinction of smaller whale species and the evidence appeared to be temporally linked to environmental changes, including seasonally intensified upwelling in coastal ecosystems. Upwelling of nutrient rich water, stimulates algal production, providing and abundance of food for krill to feed and form really dense aggregations.

Large whales were able to take advantage of feeding in these patchy, moving more efficiently than smaller whales from feeding zone to feeding zone. What happens with our oceans with climate change will continue to cause major changes. How the whales respond to these changes is yet to be seen.

Please follow the link to the original research http://rspb.royalsocietypublishing.org/content/284/1855/20170546

Slater GJ, Goldbogen JA, Pyenson ND. 2017 Independent evolution of baleen whale gigantism linked to Plio- Pleistocene ocean dynamics. Proc. R. Soc. B 284: 20170546. http://dx.doi.org/10.1098/rspb.2017.0546