Ocean Life Sizes Increased 150 Fold Over 542 Million Years, Courtesy Evolution

By Peter R - 20 Feb '15 10:00AM

A new study claims that evolution has been driving increase in average sizes of life forms in the ocean, since the Cambrian.

To arrive at their conclusions, researchers compiled body size data on some 17,000 groups of species only to find that lineages with large animals tend to branch out frequently and diversify, indicating the size increase. While fossil records show that most day modern-day life forms are larger than their ancestors, the study sets out to prove the increase is driven by evolution and not randomness, reported BBC.

"We've known for some time now that the largest organisms alive today are larger than the largest organisms that were alive when life originated or even when animals first evolved," said Jonathan Payne, one of the study's authors at Stanford University, in a news release.

Researchers ran computer simulations with their size data to see how a family tree may evolve. In some instances, simulations were not tinkered with, allowing for random drift while in some others researchers interfered with the simulation to favor large animals. The result: simulations favoring larger animals matched fossil record.

The study concluded that over the last 542 million years, average body sizes in oceans increased 150 fold, Daily Mail reported. Most notable increase was at a time when mammals and land reptiles had entered oceans.

"That's the size difference between a sea urchin about 2 inches long and one that is nearly a foot long. This may not seem like a lot, but it represents a big jump," said another researcher Noel Heim.

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