List of index fossils

Index fossils (also known as guide fossils or indicator fossils) are fossils used to define and identify geologic periods (or faunal stages). Index fossils must have a short vertical range, wide geographic distribution and rapid evolutionary trends. Another term, Zone fossil is used when the fossil have all the characters stated above except wide geographical distribution, they are limited to a zone and can't be used for correlations of strata.

Examples of index fossils[1]
Fossil Scientific Name Geological time interval Million Years Ago
Calico scallop 02.jpg
Calico scallop

Argopecten gibbus
Quaternary 1.8 million years ago
Neptunea tabulata Quaternary 1.8 million years ago
Viviparus glacialis - Rosmalen - Late Tiglian.jpg Viviparus glacialis Tiglian (Early Pleistocene) 0.5 million years ago
Calyptraphorus velatus Tertiary
Venericardia planicosta Eocene
Scaphites hippocrepis Cretaceous 145 to 66 million years ago
Inoceramus labiatus Cretaceous
Ammonit - Wüstenhaus.jpg
Perisphinctes tiziani Jurassic 201.3 to 145 million years ago
Nerinea trinodosa Jurassic
Tropites subbullatus Triassic
Monotis fossil shells - Kiritehere beach.jpg Monotis subcircularis Triassic
Leptodus americanus Permian
Parafusulina Parafusulina bosei Permian
Dictyoclostus americanus Pennsylvanian
Lophophyllidium proliferum Pennsylvanian
Cactocrinus multibrachiatus Mississippian
Prolecanites gurleyi Mississippian
Mucrospirifer mucronatus Silica Shale.JPG
Mucrospirifer mucronatus Devonian 416 to 359 million years ago
Palmatolepis unicornis Devonian
Tetragraptus fructicosus Ordovician
BLW Trilobite (Paradoxides sp.).jpg Paradoxides Cambrian 509 to 500 million years ago
Billingsella corrugata Cambrian
Archeocyathids.JPG Archaocyathids Cambrian 529 to 509 million years ago

See alsoEdit


  1. ^ Index Fossils, from the US Geological Survey. Updated July 31, 1997.