Sirenian Fossils Tell Tales of Prehistoric Water

Understanding past climate changes is critical for modeling how Earth will respond to anthropogenic global warming, and now experts have just discovered a new way of figuring out what went on millions of years ago. The found out that studying sirenians gives them a clue of Earth's prehistoric waters.

Investigators from the University of Wyoming have found in a new study that these marine animals left behind fossils which still contain a wealth of data, mostly about the waters in which they swam more than 50 million years ago.

Sirenians, distant relatives of dugongs and manatees, are commonly known as sea cows, and they were apparently alive some 15 million years after the dinosaurs died off, during the Cretaceous-Paleogene mass extinction event.

According to UW scientist and study team leader Mark Clementz, the data he and his team found in the fossils could very well change the way scientists think about the Eocene Epoch (which lasted from 56 to 34 million years ago).

In a paper published in this week's issue of the top journal Science, the team explains that the temperature and composition of seawater at the time was considerably different from what other studies have proposed until now.

The reason why the Eocene epoch is so important for science is because it marked the emergence of the first modern mammals, as the world was recovering from the last, planet-wide extinction event.

Together with study coauthor Jacob Sewall, who is based at the Kutztown University in Pennsylvania, Clementz looked at the isotopic composition of sirenian fossils, and then correlated the measurements with climate simulations based on data extracted from other sources.

“his study demonstrates the value of the fossil record, and of examining the deep time record of paleoclimatological events, so we can better understand climate change today,” Lisa Boush explains.

“This novel approach will potentially transform our way of thinking about the hydrologic response to global climate change.” adds the official, who is a program director in the US National Science Foundation (NSF) Division of Earth Sciences,.

“I wasn't looking at it from this direction when we started the project. But once we started accumulating enough samples, we could step back and get a better understanding of the habitat and dietary preferences of these fossil species, and also of the big picture,” Clementz reveals.

“We saw that it could be reflecting climate and environmental change,” he adds. One of the most interesting findings the study revealed is that sites located at low latitudes on the planet were much wetter than past investigations proposed.

“This created a very different distribution in the oxygen isotopic composition of seawater for this time interval, which would, in turn, significantly impact estimates of paleoclimate and paleotemperature in the distant past,” Clementz concludes.