What Extinct Animals Ate: New Technique Reconstructs Ancient Diet

What did extinct animals eat? That's a question that scientists are now studying, thanks to tooth enamel. Researchers have taken a look at the teeth of living mammals in hopes of using the same techniques on fossilized animals.

Reconstructing what extinct organisms once ate can be a huge challenge. Currently, researchers use a variety of methods to do so, including the structure of an animal's bones, analysis of its stomach contents, and patterns of wear left on the surface of its teeth. In addition, geochemical methods are used when remains are well preserved.

Now, researchers have found a new method. They've discovered that magnesium isotopes are particularly well suited to deciphering the diet of living mammals and when used in conjunction with other methods, can open up new perspectives on the study of fossilized animals.

"Most chemical elements exist in distinct forms called isotopes which are characterized by different masses," said Jeremy Martin, one of the researchers, in a news release. "Therefore, all the isotopes of the element will behave differently during a chemical reaction preferentially sorting out heavier ones from lighter ones."

In this case, the researchers examined teeth from various mammals living today as they explored the isotopic variability of magnesium. In the end, they found that the isotope ratios of magnesium 26 mg/24 mg increase from herbivore to higher-level consumers and can serve as a strong basis to infer the diet of mammals.

"Many fossil groups do not have living analogues and inferring their diet is far from clear," said Martin. "Applying a new perspective to palaeoecology by using non-tranditional isotopes (such as magnesium or calcium in conjunction with traditional approaches) holds great promise for our understanding of how such ancient organisms interacted with each other."

The findings are published in the journal Proceedings of the National Academy of Sciences.

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