Calcium Can Tell Us About Ancient Ecosystem Structure – #365papers – 2017 – 147

#365papers for May 27, 2017

Martin, Vincent, Tacail, Khaldoune, Jourani, Bardet, Balter, 2017, Calcium isotopic evidence for vulnerable marine ecosystem structure prior to the K/Pg extinction: Current Biology, v. 27

What’s it about?

The variations of the amounts of stable isotopes (that is non-radioactive) found in rocks and fossils can be used to help us understand patterns of weather, of vegetation, and of who’s eating whom in modern and fossil rocks, bones, teeth, and shells. Most of the time carbon, oxygen, and nitrogen are used for this.

The authors here show that calcium isotopes can be used to understand tropic level (where organisms are on the food chain) in modern and fossil animals. Their work shows that large marine reptiles likely went extinct at the end of the Permian Period because they all lived at the same trophic level. There was some sort of ecological change that eradicated their food supply and the marine reptiles could not recover.

Why does it matter?

Typically isotopes of nitrogen are used to determine the trophic level of organisms, but nitrogen-bearing molecules seldom survive fossilization. Calcium is present in bones, teeth, and shells and is preserved readily, often with no alteration. This provides scientists a tool by which we can look more closely at ancient food webs.

Why did I read this?

The key word is ‘isotopes.’ I enjoy learning about different isotope systems and their utility for studying ancient ecosystems

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