early Eocene sirenian skull
August 20, 2014

Understanding How Ancestors Of Today’s Mammals Responded To Climate Change

Marlene Cimons, National Science Foundation

Research provides valuable insights for future environmental challenges

About 10 million years into the current Cenozoic Era, or roughly 56 million years ago, during a climate that was hot and wet, two groups of mammals moved from land to water. These were the cetaceans, which include whales, dolphins and porpoises, and the sirenians, with its sea cows, manatees and dugongs.

Over time, their bodies began to adapt to their new environment. They lost their hind limbs, and their forelimbs began to resemble flippers. Their nostrils moved higher on their skulls. The cetaceans became carnivores, eating fish and squid, while the sirenians became herbivores, living on sea grasses and algae.

"It's an interesting example of evolution, and a natural experiment you don't normally have," says Mark T. Clementz, an associate professor of paleontology in the University of Wyoming's department of geology and geophysics. "The changes are so extreme, you can't really ignore them. By studying these groups, we can tease out the main environmental factors that affect mammalian groups as they move into a new environment, and a new ecosystem."

The National Science Foundation (NSF)-funded scientist believes that understanding how the ancient ancestors of today's mammals responded to climate change will provide valuable insights that will help in dealing with environmental challenges.

"A better understanding of how these mammals responded in the past will give us a more informed idea of how they will respond to climate change in the future," he says. "This could benefit conservation efforts down the road, for example, what to look out for, what things could benefit these groups, and what will hurt them if climate change goes as we project."

Moreover, "these mammals are like data loggers," he adds. "You can infer what the environmental conditions of the past were like, and how they changed over time, and you can say something about how marine ecosystems have changed over time."

The primary goal of his project is to compare the evolutionary ecology of these two orders, the Cetacea and the Sirenia, in the context of Cenozoic climate change.

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