Isotopic evidence for temperate oceans during the Cambrian Explosion

The Cambrian Explosion was a key event in the evolution of life on Earth. This event took place at a time when sea surface temperatures have been proposed to reach about 60 °C. Such high temperatures are clearly above the upper thermal limit of 38 °C for modern marine invertebrates and preclude a ma...

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Bibliographic Details
Published in:Scientific reports 2019-04, Vol.9 (1), p.6330-6330, Article 6330
Main Authors: Wotte, Thomas, Skovsted, Christian B., Whitehouse, Martin J., Kouchinsky, Artem
Format: Article
Language:English
Subjects:
140/125
704/106/2738
704/172/4081
704/829/827
Cambrian
Den föränderliga jorden
Explosions
High temperature
Humanities and Social Sciences
Invertebrates
Lethal limits
Marine invertebrates
Marine organisms
Mass spectrometry
Mass spectroscopy
multidisciplinary
Oceans
Science
Science (multidisciplinary)
Sea surface temperature
The changing Earth
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Summary:The Cambrian Explosion was a key event in the evolution of life on Earth. This event took place at a time when sea surface temperatures have been proposed to reach about 60 °C. Such high temperatures are clearly above the upper thermal limit of 38 °C for modern marine invertebrates and preclude a major biological revolution. To address this dichotomy, we performed in situ δ 18 O analyses of Cambrian phosphatic brachiopods via secondary ion mass spectrometry (SIMS). The δ 18 O phosphate data, which are considered to represent the most primary δ 18 O seawater signature, were identified by evaluating the diagenetic alteration of the analyzed shells. Assuming ice-free conditions for the Cambrian ocean and no change in δ 18 O seawater (-1.4‰ to -1‰; V-SMOW) through time, our temperatures vary between 35 °C ± 12 °C and 41 °C ± 12 °C. They are thus clearly above (1) recent subequatorial sea surface temperatures of 27 °C–35 °C and (2) the upper lethal limit of 38 °C of marine organisms. Our new data can therefore be used to infer a minimal depletion in early Cambrian δ 18 O seawater relative to today of about -3‰. With this presumption, our most pristine δ 18 O phosphate values translate into sea surface temperatures of about 30 °C indicating habitable temperatures for subequatorial oceans during the Cambrian Explosion.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-019-42719-4