List of index fossils

(Redirected from Zone fossil)

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.

Examples of index fossils[1]
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

See also

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References

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