The study’s authors write in the abstract of their paper, published in the journal Science, that they looked at 17,208 types of marine animals going back 542 million years to a key evolutionary epoch known as the Cambrian: “Mean biovolume across genera has increased by a factor of 150 since the Cambrian, whereas minimum biovolume has decreased by less than a factor of 10, and maximum biovolume has increased by more than a factor of 100,000.”
In other words, the scientist looked at lots of marine animals over a huge evolutionary time span. Their conclusion: The small creatures got a little smaller and the big ones got a lot bigger.
Think whales. The blue whale is not only the largest creature to currently exist on Earth, but also the largest known ever to have existed.
“It’s easier to eat other animals if you’re large. It’s also easier to avoid being eaten,” Stanford paleobiologist Noel Heim, the lead author on the study
“In water, larger animals can be more active because of the increased mass relative to their surface area. They feel less ‘drag’ than small animals. Larger animals also have a higher metabolic rate, which also contributes to a more active lifestyle,” Heim added.
