original |
Late Ordovician |
Early Gothlandian |
Scotland(Ayr) |
Whelan,G.M. Preliminary acritarch and chitinozoan distributions across Ordovician-Silurian boundary stratotype at Dob's Linn, Scotland. (In: A Global Analysis of the Ordovician-Silurian Boundary. L.R.M.Cocks and R.B.Rickards, editors) |
1988 |
original |
Late Caradocian |
Ashgillian |
Canada(Arctic) |
Achab,A. et al. Ordovician chitinozoans from the Arctic Platform and the Franklinian Miogeosyncline in northern Canada |
1995 |
original |
Late Ordovician |
|
Nevada |
Finney,S.C. et al. Late Ordovician mass extinction: A new perspective from stratigraphic sections in Central Nevada. |
1999 |