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. [1]
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 |
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