microfossile caractéristique

CONT: Les ""microfossiles caractéristiques"" (...) sont surtout ceux de relativement grande taille. Leur extension stratigraphique doit être brève, mais elle est grande en horizontale, conditions excellentes pour l'établissement des raccords et des dates.

OBS: index fossil: A [microfossil] that identifies and dates the strata or succession of strata in which it is found; esp. any fossil taxon (...) that combines morphologic distinctiveness with relatively common occurrence or great abundance and that is characterized by a broad, even worldwide geographic range and by a narrow or restricted stratigraphic range (range zone) that may be demonstrated to approach isochroneity.