articleScienceJul 24, 2008Closed access

Did Cooling Oceans Trigger Ordovician Biodiversification? Evidence from Conodont Thermometry

Université Claude Bernard Lyon 1 · Australian National University · +3 more institutions

PubMed
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Abstract

The Ordovician Period, long considered a supergreenhouse state, saw one of the greatest radiations of life in Earth's history. Previous temperature estimates of up to approximately 70 degrees C have spawned controversial speculation that the oxygen isotopic composition of seawater must have evolved over geological time. We present a very different global climate record determined by ion microprobe oxygen isotope analyses of Early Ordovician-Silurian conodonts. This record shows a steady cooling trend through the Early Ordovician reaching modern equatorial temperatures that were sustained throughout the Middle and Late Ordovician. This favorable climate regime implies not only that the oxygen isotopic…

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