Ocean Temperatures in the Late Ordovician: A Clumped Isotope Study of Brachiopods and Cements

Abstract

Throughout the Phanerozoic, δ 18 O of carbonate fossils displays an increasing trend of -8‰ VPDB in the Cambrian to approximately -1‰ VPDB in the modern. This trend has led to three different hypotheses: 1) sea surface temperatures decreased through the Phanerozoic; 2) δ 18 O of seawater rose through the Phanerozoic, or 3) diagenesis has altered older samples more than younger samples. To test these Cincinnati Natural History Museum & Science for allowing access to their fossil collections. Also, thanks to Dr. Brenda Hunda from the Cincinnati Museum of Natural History & Science and Don Bissett from the Cincinnati Dry Dredgers for their help with fossil collection in the field.