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 has all the characters stated above except wide geographical distribution; thus, they correlate the surrounding rock to a biozone rather than a specific time period.

List of index fossils in chronological order
ImageScientific NameGeological time intervalPeriod
(million years ago)

Calico scallop
Argopecten gibbus		Quaternary1.8
Neptunea tabulataQuaternary1.8
Viviparus glacialisTiglian (Early Pleistocene)2.3–1.8
Calyptraphorus velatusTertiary
Venericardia planicostaEocene

Scaphites		Scaphites hippocrepisCretaceous143.1–66

Inoceramus		Inoceramus labiatusCretaceous

Perisphinctes		Perisphinctes tizianiJurassic201.3–145
Nerinea trinodosaJurassic
Tropites subbullatusTriassic
Monotis subcircularisTriassic

Leptodus		Leptodus americanusPermian
ParafusulinaParafusulina boseiPermian
Dictyoclostus americanusPennsylvanian
Lophophyllidium proliferumPennsylvanian
Cactocrinus multibrachiatusMississippian
Prolecanites gurleyiMississippian

Mucrospirifer		Mucrospirifer mucronatusDevonian416–359
Palmatolepis unicornisDevonian
Tetragraptus fructicosusOrdovician
ParadoxidesCambrian509–500
Billingsella corrugataCambrian
ArchaocyathidsCambrian529–509
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