Extinction of Cloudina and Namacalathus at the Precambrian-Cambrian boundary in Oman

@article{Amthor2003ExtinctionOC,
  title={Extinction of Cloudina and Namacalathus at the Precambrian-Cambrian boundary in Oman},
  author={Joachim E. Amthor and John P. Grotzinger and Stefan Schr{\"o}der and Samuel A. Bowring and Jahandar Ramezani and Mark W. Martin and Albert Matter},
  journal={Geology},
  year={2003},
  volume={31},
  pages={431-434}
}
Biostratigraphic, carbon isotope, and U-Pb zircon geochronological data from the Ara Group of Oman indicate an abrupt last appearance of Cloudina and Namacalathus coincident with a large-magnitude, but short-lived negative excursion in the carbon isotope composition of seawater that is globally coincident with the Precambrian-Cambrian boundary. U-Pb zircon age data from an intercalated ash bed directly define this negative excursion to be at 542.0 ± 0.3 Ma, consistent with previous age… Expand
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