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|Subdivision of the Jurassic system|
according to the ICS, as of 2017.
In the geologic timescale, the Kimmeridgian is an age or stage in the Late or Upper Jurassic epoch or series. It spans the time between 157.3 ± 1.0 Ma and 152.1 ± 0.9 Ma (million years ago). The Kimmeridgian follows the Oxfordian and precedes the Tithonian.
- 1 Stratigraphic definition
- 2 Palaeontology
- 3 References
- 4 External links
The Kimmeridgian stage takes its name from the village of Kimmeridge on the Dorset coast, England. The name was introduced in literature by Swiss geologist Jules Thurmann in 1832. The Kimmeridge Clay Formation has its name from the same type location. It is the source for about 95% of the petroleum in the North Sea.
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 (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; As of 2004[update] Tithonian is the uppermost stage of the Jurassic in the timescale of the ICS.
The base of the Kimmeridgian is at the first appearance of ammonite species Pictonia baylei in the stratigraphic column. A global reference profile for the base (the GSSP of the Kimmeridgian stage) had in 2009 not yet been assigned. The top of the Kimmeridgian (the base of the Tithonian) is at the first appearance of ammonite species Hybonoticeras hybonotum. It also coincides with the top of magnetic anomaly M22An.
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|Ankylosaurs of the Kimmeridgian|
||Morrison Formation, Wyoming, USA||The smallest and the earliest well-known ankylosaur. Its skull measures only 29 cm in length, and its total body length is an estimated three to four meters.|
||Morrison Formation, Colorado, USA||A poorly known early ankylosaurian.|
|Birds of the Kimmeridgian|
|Ornithopoda of the Kimmeridgian|
|Kimmeridgian to Tithonian||Wyoming, USA||Camptosaurus could be more than 7.9 meters (26 feet) long, and 2.0 meters (6.6 feet) tall at the hips. It had heavy bodies but, as well as walking on four legs (quadrupedal), they could rear up to walk on two legs (bipedal). This genus is probably closely related to the ancestor of the later iguanodontid and hadrosaurid dinosaurs. It probably ate cycads with its parrot-like beak.|
|Plesiosaurs of the Kimmeridgian|
|†Sauropods of the Kimmeridgian|
|Kimmeridge Clay Formation, England|
|Morrison Formation, Colorado|
|Kimmeridge Clay Formation, Dorset, England||The genus is preoccupied by a name Edward Drinker Cope coined in 1869.|
|Stegosaurs of the Kimmeridgian|
|England and France||A large stegosaurid|
|Upper Shaximiao Formation, Sichuan, China||Had relatively small dorsal plates and greatly enlarged shoulder spines, twice the length of the shoulder blades. Estimated to have been about 4 metres long.|
|Lourinhã Formation, Portugal||Closer to Dacentrurus than Stegosaurus.|
|*Hesperosaurus||Morrison Formation, Wyoming, USA||Had alternating plates on its back and four spikes on its tail. Appears more closely related to Dacentrurus than Stegosaurus.|
|Tanzania||A 4 meter long stegosaurian with spikes on its flanks. The length of the thigh bone compared with the rest of the leg indicates that Kentrosaurus was a slow and inactive dinosaur.|
|Loe-ein Formation, Tibet, China||The fragmentary condition of the only known skeleton places doubt on the validity of this genus|
|Kimmeridgian to Early Tithonian||Morrison Formation, Colorado, Utah, Wyoming, USA||Averaging around 9 metres (30 feet) long and 4 metres (13 feet) tall, the quadrupedal Stegosaurus is one of the most easily identifiable dinosaurs, due to the distinctive double row of kite-shaped plates rising vertically along its arched back and the two pairs of long spikes extending horizontally near the end of its tail.|
|Thalattosuchians of the Kimmeridgian|
||Germany||A relatively small metriorhynchid genus.|
||Germany||type species of the genus, is known from Western Europe (England, France, Switzerland and Germany) of the Late Jurassic (Late Kimmeridgian-Early Tithonian).|
||England, France and Switzerland||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 (9.8 feet).|
||Kimmeridge Clay Formation, Wiltshire, England; Oaxaca, Mexico|
|†Non-avian theropods of the Kimmeridgian|
||Guimarota Mine, Portugal||Small 5 kg tyrannosauroid. Avityrannis along with Stokesosaurus represents the oldest known tyrannosauroids.|
||Morrison Formation, Wyoming||Small theropod about 2 metres in length|
||Tendaguru Beds, Tanzania||Probably a ceratosaur about 6 meters long|
||Cleveland-Lloyd Quarry, Brushy Basin Member, Morrison Formation, Utah and possibly Colorado|
||Morrison Formation, Wyoming|
|Nautiloids of the Kimmeridgian|
|Ammonites of the Kimmeridgian|
|Belemnites of the Kimmeridgian|
- For a detailed version of the ICS' timescale, see Gradstein et al. (2004)
- INTERNATIONAL SUBCOMMISSION ON JURASSIC STRATIGRAPHY, Newsletter 31, Edited by Nicol Morton and Paul Bown, August 2004
- "Global Boundary Stratotype Section and Point (GSSP) of the International Commission on Stratigraphy". GSSP Table - All Periods. International Commission on Stratigraphy. Retrieved 5 January 2018.
- Mateus, Octávio; Hendrickx, Christophe (5 March 2014). "Torvosaurus gurneyi n. sp., the Largest Terrestrial Predator from Europe, and a Proposed Terminology of the Maxilla Anatomy in Nonavian Theropods". PLOS ONE. 9 (3): e88905. doi:10.1371/journal.pone.0088905. ISSN 1932-6203. PMC 3943790.
- Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
- Thurmann, J.; 1832: Sur Les Soulèvemens Jurassiques Du Porrentruy: Description Géognostique de la Série Jurassique et Théorie Orographique du Soulèvement, Mémoires de la Société d'histoire naturelle de Strasbourg 1: pp 1–84, F. G. Levrault, Paris.(in French)