Date a rock from its fossils

Tick the fossils found in a rock and this brackets its likely age — the way relative dating works, by intersecting the geological ranges of the fossils present. The narrowest overlap is the answer.

How it works & what it is (and isn’t)

A rock can be no older than its youngest fossil’s first appearance and no younger than its oldest fossil’s last appearance. Intersecting every fossil’s range leaves the window the rock must fall in; the fossils that set each edge are its tightest constraints.

This is a teaching tool. Ages here are the established worldwide ranges of each taxon at period/epoch resolution — general reference values, not sourced first/last-appearance datums. Real biostratigraphy uses finer, calibrated zonations (stages, biozones) with cited datums and stated uncertainty. Only fossils with a numeric range are offered — group notes and undated fossils are omitted.

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Arthropods

Ostracods Ordovician – Recent Trilobite trails (trace fossils) Cambrian – Permian Trilobites (rare) Cambrian – Permian Trilobites (Redlichia noetlingi) Cambrian – Permian

Brachiopods

Brachiopods Cambrian – Recent Brachiopods (Lingulella fuchsia, Botsfordia granulata) Cambrian – Recent Brachiopods (Neobolus warthi, Lingulella) Cambrian – Recent Brachiopods (productids) Cambrian – Recent Brachiopods (Productus) Cambrian – Recent Chonetes Devonian – Permian Chonetes sp Devonian – Permian Last Paleozoic brachiopods Cambrian – Recent Neochonetes Carboniferous – Permian Productid brachiopods Devonian – Permian Productids Devonian – Permian Spirelytha petaliformis Permian

Corals

Corals Ordovician – Recent Corals (in limestone interbeds) Ordovician – Recent Rugose corals Ordovician – Permian Stromatoporoids Ordovician – Devonian

Echinoderms

Crinoids Ordovician – Recent Echinoids Ordovician – Recent Echinolampas nummulitica Eocene – Recent

Foraminifera

Alveolina Paleocene – Eocene Alveolina elliptica Paleocene – Eocene Alveolina oblonga Paleocene – Eocene Alveolina vredenburgi Paleocene – Eocene Assilina dandotica Paleocene – Eocene Assilina daviesi Paleocene – Eocene Assilina elliptica Paleocene – Eocene Assilina exponens Paleocene – Eocene Assilina granulosa Paleocene – Eocene Assilina laminosa Paleocene – Eocene Assilina mamilla Paleocene – Eocene Assilina pustulosa Paleocene – Eocene Assilina spinosa Paleocene – Eocene Benthic foraminifera Cambrian – Recent Daviesina longhami Paleocene – Eocene Deep water foraminifera Cambrian – Recent Dictyoconoides cooki Eocene Discocyclina Paleocene – Eocene Discocyclina ranikotensis Paleocene – Eocene Discocyclina undulata Paleocene – Eocene Fasciolites borealis Paleocene – Eocene Fasciolites oblonga Paleocene – Eocene Flosculina globosa Eocene Foraminifera Cambrian – Recent Fusulinid foraminifera Carboniferous – Permian Fusulinids Carboniferous – Permian Globogerina pseudobulloides Paleocene – Recent Globorotalia aequa Paleocene – Recent Globorotalia quadrata Paleocene – Recent Larger foraminifera Carboniferous – Recent Larger foraminifera (Nummulites, Assilina) Carboniferous – Recent Lepidocyclina blanfordi Eocene – Miocene Lepidocyclina dilatata Eocene – Miocene Lepidocyclina punjabensis Eocene – Miocene Lepidorbitoides socialis Late Cretaceous Linderina brugesi Eocene Lockhartia conditi Paleocene – Eocene Lockhartia haimei Paleocene – Eocene Lockhartia newboldi Paleocene – Eocene Lockhartia tipperi Paleocene – Eocene Miliolids Carboniferous – Recent Miscellanea miscella Paleocene Miscellanea stampi Paleocene Neoschwagerina sp. Permian Nummulites Paleocene – Oligocene Nummulites atacicus Paleocene – Oligocene Nummulites beaumonti Paleocene – Oligocene Nummulites fichteli Paleocene – Oligocene Nummulites intermedius Paleocene – Oligocene Nummulites mamillatus Paleocene – Oligocene Nummulites sp. Paleocene – Oligocene Nummulites subbeaumonti Paleocene – Oligocene Nummulites vascus Paleocene – Oligocene Omphalocyclus sp. Late Cretaceous Omphaocyclus sp Late Cretaceous Operculina Paleocene – Recent Operculina canalifera Paleocene – Recent Operculina subsalsa Paleocene – Recent Opertorbitolites douvillei Eocene Orbitoides sp. Late Cretaceous Orbitolina Cretaceous Orbitolites complanatus Paleocene – Eocene Other larger foraminifera Carboniferous – Recent Parafusulina sp. Permian Paraschwagerina sp. Permian Planktic foraminifera Jurassic – Recent Planktonic foraminifera Jurassic – Recent Planktonic foraminifera (Globotruncana spp.) Jurassic – Recent Rotalia crookshankiana Cretaceous – Recent Spiroclypeus sp. Eocene – Miocene

Microflora & algae

Algae Precambrian – Recent Algal mats Archean – Recent Calcareous algae Cambrian – Recent Calcareous nannofossils Triassic – Recent Coccoliths Triassic – Recent Conodonts Cambrian – Triassic Dinoflagellates Triassic – Recent Nannofossils Triassic – Recent Neospathodus dieneri Early Triassic Stromatolites Archean – Recent Stromatolites (rare) Archean – Recent

Molluscs

Ambites Early Triassic Ammonites Jurassic – Cretaceous Ammonites (Bouleiceras) Jurassic – Cretaceous Ammonites, brachiopods, bivalves, crinoids, corals Jurassic – Cretaceous Ammonoids Devonian – Cretaceous Ammonoids (Ceratites) Devonian – Cretaceous Ammonoids (rare) Devonian – Cretaceous Barbatia drougensis Cretaceous – Recent Belemnites Triassic – Cretaceous Bivalves Cambrian – Recent Bivalves (lamellibranchs) Cambrian – Recent Bullatimorphites bullatus Middle Jurassic Cephalopods Cambrian – Recent Choffatia Middle Jurassic Claraia bivalves Early Triassic Clydoniceras Middle Jurassic Conularia Cambrian – Triassic Daonella Triassic Eurydesma Permian Eurydesma sp. Permian Freshwater bivalves Cambrian – Recent Freshwater molluscs Cambrian – Recent Gastropods Cambrian – Recent Gyronites Early Triassic Hippurites loftusi Late Cretaceous Hyolithes wynnei Cambrian – Permian Hyolithids Cambrian – Permian Inoceramid fragments Jurassic – Cretaceous Kingites Early Triassic Koninckites Early Triassic Lower Toarcian ammonites (Bouleiceras, Protogrammoceras); brachiopods, corals Jurassic – Cretaceous Megalodon Triassic – Jurassic Megalodont bivalves Triassic – Jurassic Megalodontidae (bivalves) Triassic – Jurassic Molluscs Cambrian – Recent Mollusks Cambrian – Recent Nautiloids Cambrian – Recent Ophiceras ammonoids Early Triassic Ostreids Triassic – Recent Oysters Triassic – Recent Pelecypods Cambrian – Recent Proptychites Early Triassic Rudists (Hippurites) Jurassic – Cretaceous Trigonia-type bivalves Cambrian – Recent Vavilovites Early Triassic Velates perversus Cretaceous – Eocene

Other

Bryozoa Ordovician – Recent Bryozoans Ordovician – Recent Fenestella Ordovician – Permian Sponges Cambrian – Recent

Plants

Gangamopteris Permian Glossopteris Permian

Vertebrates

Amphicyon cf. shahbazi Oligocene – Miocene Anthracotherium sp. Eocene – Miocene Basilosaurids Eocene Conohyus cf. sindiensis Miocene Dinotherium indicum Miocene – Pleistocene Gandakasia Early Eocene Giraffokeryx Miocene Hemimeryx blanfordi Oligocene – Miocene Hipparionine (three-toed) horses Miocene – Pleistocene Hyaenaelurus lahirii Miocene Ichthyolestes Early Eocene Listriodon cf. guptai Miocene Listriodon pentapotomiae Miocene Middle Siwalik mammals (incl. hipparionine horses) Miocene – Pleistocene Pakicetus Early Eocene Pterosaurs Triassic – Cretaceous Shark teeth Devonian – Recent Sivapithecus Miocene Stegodon Miocene – Pleistocene Theropod dinosaurs Triassic – Cretaceous Titanosaurian sauropods Cretaceous Trilophodon cf. angustidens Miocene – Pliocene Walking whales (Ambulocetus) Eocene

No fossils match.

Select the fossils found in your rock to estimate its age.

Two or more index fossils give the tightest bracket.

Estimated age of the rock

These fossils don’t overlap in time

Each fossil’s range, and the overlap that dates the rock:

Pakistan Stratigraphy

A free field reference to the geology of Pakistan — every formation, province and era of the rock record, in one place.

Compiled from the published geological literature on Pakistan and curated by Lareb Qudsi.

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