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

Examples of index fossils[1]
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See also
References
- Index Fossils, from the US Geological Survey. Updated July 31, 1997.
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