Carbonate Shells of the Freshwater Gastropod Viviparus lentus (image) University of Connecticut Share Print E-Mail Caption Michael Hren of the University of Connecticut and his coauthors examined these carbonate shells of the freshwater gastropod Viviparus lentus from the Hampshire Basin, United Kingdom. They used a clumped-isotope thermometer technique to determine the concentration of bonded heavy oxygen and carbon isotopes in these shells, which gives a picture of land temperatures during the Eocence-Oligocene transition, about 34 million years ago. Terrestrial temperatures were determined to be closely linked to atmospheric carbon dioxide. Credit Photo courtesy Michael Hren. Usage Restrictions Image and caption embargoed for public release 3 p.m. EDT Monday, April 22, 2013. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.