Size variation of conodonts during the SmithianSpathian (Early Triassic) global warming event
Yanlong Chen et al., Institute of Earth Sciences, University of Graz, Heinrichstrasse 26, 8010 Graz, Austria; and State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Wuhan), Hubei 430074, China. First published on 28 June 2013, http://dx.doi.org/10.1130/G34171.1.
The end-Permian mass extinction is believed to be the most severe biodiversity crisis in the history of life. Immediately after the extinction, many marine taxa suffered a temporary but dramatic size reduction (i.e., the 'Lilliput Effect'). Compiled data show that recovery from the end-Permian mass extinction was not a smooth process but included several episodes of environmental disturbance and three further episodes of extinction. The third one occurs near the Smithian/Spathian boundary (SSB), around 1.8 million years after the end-Permian extinction and was recently associated to an episode of extreme warmth. Ammonoids and Conodonts suffered especially. Conodonts are an extinct group of marine chordates with a feeding apparatus composed of microscopic 'tooth-like' elements. They are one of the fastest evolving fossil groups, sensitive to environment stress, and are thus an ideal organism to test ecological responses to past episodes of climatic change. Detailed size measurements show for the first time that this clade suffered a temporary, but significant, size reduction during the SSB crisis, followed by gradual and steady size increase. Size reduction of conodonts was caused by an episode of global warming, further strengthening the link between morphological and climatic changes recorded in the fossil record.
Magnetostratigraphic determination of the age of ancient La
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