Conodont biostratigraphy

Conodonts are an extinct class of animals whose feeding apparatuses called teeth or elements are common microfossils found in strata dating from the Stage 10 of the Furongian, the fourth and final series of the Cambrian, to the Rhaetian stage of the Late Triassic. These elements can be used alternatively to or in correlation with other types of fossils (graptolites, trilobites, ammonites, ...) in the subfield of the stratigraphy named biostratigraphy.

It is suggested that Eoconodontus notchpeakensis can be a marker of the Stage 10 of the Furongian, the fourth and final series of the Cambrian.

In 2006, a working group proposed the first appearance of Cordylodus andresi. Currently the first appearance of E. notchpeakensis is favored by many authors because it is globally widespread and is independent of facies (known from continental rise to peritidal environments).

The Eoconodontus notchpeakensis proposal would also incorporate a non-biostratigraphic marker to correlate the beginning of Stage 10 globally. A carbon isotope excursion (the HERB-event) occurs in the lower part of the E. notchpeakensis range.

The base of the Tremadocian, the lowest stage of Ordovician, is defined as the first appearance of Iapetognathus fluctivagus at the GSSP section in Newfoundland.

No conodont species is associated with the Floian, the second stage of the Ordovician.

The base of the Dapingian, the third stage of the Ordovician, is defined as the first appearance of Baltoniodus triangularis.

The base of the Darriwilian, the fourth stage of the Ordovician, lies just above the North Atlantic Microzarkodina parva conodont zone. The base also lies in the upper part of the North American Histiodella altifrons conodont zone.

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