LIFE × EVOLUTION

The Largest Animal Ever

~4.5 million years ago

Phanerozoic · Cenozoic · Neogene · Pliocene

Filter feeding is old, but whales the size of a blue whale are recent. For most of their history baleen whales stayed moderate; then, in the last few million years, several lineages independently began trending towards enormous size. What changed was not how much food the ocean held but how it was arranged: glacial cycles concentrated it into seasonal upwellings along the coasts.

Why it matters

A filter feeder does not care about the total amount of prey, it cares about how densely it is packed, because it has to swim through it. Dense, seasonal, predictable patches reward an animal big enough to travel between them and to fast in between. The largest animal that ever lived is alive now, and it owes its size to the ice ages.

Dating & uncertainty

Baleen whales stayed moderate in size for most of their history and became giants only in the last few million years. The link to ice-age upwelling rests on the timing and on body-size modelling, not on any direct measure of ancient food supply, and the threshold date moves with the dataset.

Sources

1. Slater, Goldbogen & Pyenson (2017), Proceedings of the Royal Society B · Independent evolution of baleen whale gigantism linked to Plio-Pleistocene ocean dynamics
2. Lisiecki & Raymo (2005), Paleoceanography · A Pliocene-Pleistocene stack of 57 globally distributed benthic oxygen isotope records

Earth history as one day

23:58:341 min 26 s before midnight

if Earth’s 4.54 billion years were compressed into a single day