Kimmeridgian

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System/
Period		 Series/
Epoch		 Stage/
Age		 Age (Ma)
Cretaceous Lower/
Early		 Berriasian younger
Jurassic Upper/
Late		 Tithonian 145.0–152.1
Kimmeridgian 152.1–157.3
Oxfordian 157.3–163.5
Mid/
Middle		 Callovian 163.5–166.1
Bathonian 166.1–168.3
Bajocian 168.3–170.3
Aalenian 170.3–174.1
Lower/
Early		 Toarcian 174.1–182.7
Pliensbachian 182.7–190.8
Sinemurian 190.8–199.3
Hettangian 199.3–201.3
Triassic Upper/
Late		 Rhaetian older
Subdivision of the Jurassic system
according to the IUGS, as of July 2012.

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

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, but Tithonian is now seen as the uppermost stage of the Jurassic in the timescale of the ICS.[2]

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.

Subdivision

The Kimmeridgian is sometimes subdivided into Upper and Lower substages. In the Tethys domain, the Kimmeridgian contains seven ammonite biozones:

Palaeontology

†Ankylosaurs

Ankylosaurs of the Kimmeridgian
Taxa Presence Location Description Images
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.
Gargoyleosaurus skeleton
  • Mymoorapelta maysi
 Morrison Formation, Colorado, USA A poorly known early ankylosaurian.

Birds

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

†Ornithopods

Ornithopoda of the Kimmeridgian
Taxa Presence Location Description Images
Kimmeridgian to ?Berriasian Wyoming, USA; England; France Camptosaurus could be more than 7.9 meters long (26 ft), and 2.0 meters tall (6.7 ft) 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.
Othnielosaurus

†Plesiosaurs

Plesiosaurs of the Kimmeridgian
Taxa Presence Location Description Images
Liopleurodon

†Sauropods

†Sauropods of the Kimmeridgian
Taxa Presence Location Description Images
  • Amphicoelias
Europasaurus holgeri
  • Europasaurus holgeri

†Stegosaurs

Stegosaurs of the Kimmeridgian
Taxa Presence Location Description Images
England, France, Spain, Portugal A large stegosaurid
Dacentrurus
Stegosaurus
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.
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 ft) long and 4 metres (14 ft) 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

Thalattosuchians of the Kimmeridgian
Taxa Presence Location Description Images
D. maximus
 Germany type species of the genus, is known from Western Europe (England, France, Switzerland and Germany) of the Late Jurassic (Late Kimmeridgian-Early Tithonian).
Dakosaurus, a marine crocodilian.
G. suevicus
 Germany A relatively small metriorhynchid genus. No known species of Geosaurus attained lengths in excess of 3 meters (10 feet).
Geosaurus, a marine crocodilian.
  1. M. acutus
  2. M. geoffroyii
  3. M. hastifer
  4. M. palpebrosus
 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 (9.6 feet).
Metriorhynchus, a marine crocodilian.

†Theropods (non-avian)

†Non-avian theropods of the Kimmeridgian
Taxa Presence Location Description Images
  • Aviatyrannis jurassica
 Guimarota Mine, Portugal Small 5 kg tyrannosauroid. Avityrannis along with Stokesosaurus represents the oldest known tyrannosauroids.
Ceratosaurus
Elaphrosaurus
Torvosaurus
  • Coelurus fragilis
 Morrison Formation, Wyoming Small theropod about 2 metres in length
  • Elaphrosaurus bambergi
 Tendaguru Beds, Tanzania Probably a ceratosaur about 6 meters long
  • Stokesosaurus clevelandi
  • Torvosaurus tanneri
  • Torvosaurus gurneyi

Nautiloids

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

†Ammonites

Ammonites of the Kimmeridgian
Taxa Presence Location Description Images
  • Lithacosphinctes
Lithacosphinctes achilles.

†Belemnites

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

Palaeontological sites

References

Notes

  1. ↑ For a detailed version of the ICS' timescale, see Gradstein et al. (2004)
  2. ↑ INTERNATIONAL SUBCOMMISSION ON JURASSIC STRATIGRAPHY, Newsletter 31, Edited by Nicol Morton and Paul Bown, August 2004

Literature

  • 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.(French)

External links

Jurassic Period
Lower/Early Jurassic Middle Jurassic Upper/Late Jurassic
Hettangian | Sinemurian
Pliensbachian | Toarcian		 Aalenian | Bajocian
Bathonian | Callovian		 Oxfordian | Kimmeridgian
Tithonian
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