Kimmeridgian

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The Kimmeridgian is a stage of the Late Jurassic Epoch. It spans the time between 155.7 ± 4 Ma and 150.8 ± 4 Ma (million years ago). The Kimmeridgian stage follows the Oxfordian stage and precedes the Tithonian stage.

The stage takes its name from the village of Kimmeridge on the Dorset coast, England where the exposure is at its greatest extent. The beach at Kimmeridge Bay is a good place for looking for fossils — there are specimens on the beach washed in by the tide.

The Kimmeridge Clay formation is the source for about 95% of the petroleum in the North Sea.

[edit] Usage of the term

Historically the term Kimmeridgian has been used in two different ways. The base of the interval is the same but the top was defined by British stratigraphers as the base of the Portlandian stage (sensu anglico) whereas in France the top was defined as the base of the Tithonian (sensu gallico). The differences have not yet been fully resolved, although Kimmeridge-Tithonian are now the agreed terms globally^[1]

[edit] Vertebrate Fauna

[edit] Birds

Birds of the Kimmeridgian
Taxa	Presence	Location	Description	Images
Archaeopteryx Archaeopteryx lithographica				A model depicting how Archaeopteryx lithographica is believed to appear in life.

[edit] Plesiosaurs

Plesiosaurs of the Kimmeridgian
Taxa	Presence	Location	Description	Images
Liopleurodon				Liopleurodon Pliosaurus
Pliosaurus

[edit] Sauropods

†Sauropods of the Kimmeridgian
Taxa	Presence	Location	Description	Images
Amphicoelias Amphicoelias fragillimus?				Camarasaurus Diplodocus Europasaurus holgeri
Camarasaurus
Diplodocus
Dystrophaeus
Europasaurus Europasaurus holgeri

[edit] Stegosaurs

[edit] Thalattosuchians

Thalattosuchians of the Kimmeridgian
Taxa	Presence	Location	Description	Images
Dakosaurus Dakosaurus maximus			type species of the genus, is known from Western Europe (England, France, Switzerland and Germany) of the Late Jurassic (Late Kimmeridgian-Early Tithonian).	Metriorhynchus, a marine crocodilian.
Metriorhynchus			An opportunistic carnivore that fed on fish, belemnites and other marine animals and possible carrion. Metriorhynchus grew to an average adult length of 3 meters (9.6 feet), although some individuals may have reached lengths rivaling those of large nile crocodiles.

[edit] Theropods

[edit] Invertebrate Fauna

[edit] Nautiloids

Nautiloids of the Oxfordian
Taxa	Presence	Location	Description	Images
Somalinautilus				An illustration of a variety of fossil nautiloids.

[edit] Belemnites

Belemnites of the Kimmeridgian
Taxa	Presence	Location	Description	Images
Produvalia				Small belemnite fossils

[edit] Environment

Ammonites such as this Jurassic period ammonite were common during the latest environment of the Kimmeridgian stage.

The variation of fauna during the Kimmeridgian stage indicates the existence of two distinct environments, the first being a being a shallow and agitated layer abundant in pebbles and fossils and the second following environment being a calm and deep layer marked by an absence of pebbles and by an abundance of pelagic organisms, such as Ammonites.

[edit] Localities

• Guimarota

[edit] References

1. ^ SUBCOMMISSION ON JURASSIC STRATIGRAPHY, Newsletter 31, Edited by Nicol Morton and Paul Bown, August 2004

• GeoWhen Database - Kimmeridgian