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 stratas.

Fossil	Scientific Name	Time Period	Million Years Ago
Calico Scallop	Pecten gibbus Argopecten gibbus	Quaternary Period	1.8 million years ago
	Neptunea tabulata	Quaternary Period	1.8 million years ago
	Viviparus glacialis	Tiglian (Early Pleistocene)	0.5 million years ago
	Calyptraphorus velatus	Tertiary Period
	Venericardia planicosta	Eocene
Scaphites	Scaphites hippocrepis	Cretaceous Period	145 to 66 million years ago
Inoceramus	Inoceramus labiatus	Cretaceous Period
Perisphinctes	Perisphinctes tiziani	Jurassic Period	201.3 to 145 million years ago
	Nerinea trinodosa	Jurassic Period
	Tropites subbullatus	Triassic Period	145 to xxx million years ago
	Monotis subcircularis	Triassic Period
Leptodus	Leptodus americanus	Permian Period	xxx to xxx million years ago
Parafusulina	Parafusulina bosei	Permian Period
	Dictyoclostus americanus	Pennsylvanian Period	xxx to xxx million years ago
	Lophophyllidium proliferum	Pennsylvanian Period
	Cactocrinus multibrachiatus	Mississippian Period	xxx to 416 million years ago
	Prolecanites gurleyi	Mississippian Period
Mucrospirifer	Mucrospirifer mucronatus	Devonian Period	416 to 359 million years ago
	Palmatolepis unicornis	Devonian Period
		Silurian Period	359 to xxx million years ago
	Tetragraptus fructicosus	Ordovician Period	xxx to 509 million years ago
	Paradoxides	Cambrian Period	509 to 500 million years ago
	Billingselia corrugata	Cambrian Period
	Archaocyathids	Lower Cambrian	529 to 509 million years ago

Examples of index fossilsg