Editing Cambrian (section)

==== Cambrian–Ordovician boundary ====
The GSSP for the Cambrian–Ordovician boundary is at [[Green Point, Newfoundland and Labrador|Green Point]], western [[Newfoundland and Labrador|Newfoundland]], Canada, and is dated at 486.85 Ma. It is defined by the appearance of the [[conodont]] ''[[Iapetognathus fluctivagus]]''. Where these conodonts are not found the appearance of [[plankton]]ic [[graptolite]]s or the [[trilobite]] ''Jujuyaspis borealis'' can be used. The boundary also corresponds with the peak of the largest positive variation in the δ<sup>13</sup>C curve during the boundary time interval and with a global marine transgression.<ref>{{Citation |last1=Cooper |first1=R.A. |title=The Ordovician Period |date=2012 |work=The Geologic Time Scale |pages=489–523 |url=https://doi.org/10.1016/B978-0-444-59425-9.00020-2 |access-date=2024-05-12 |publisher=Elsevier |doi=10.1016/b978-0-444-59425-9.00020-2 |isbn=978-0-444-59425-9 |last2=Sadler |first2=P.M. |last3=Hammer |first3=O. |last4=Gradstein |first4=F.M.}}</ref>