Kimmeridgian

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.[2]

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
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 ICS, as of 2020.[1]

Stratigraphic definition

The Kimmeridgian stage takes its name from the village of Kimmeridge on the Dorset coast, England. The name was introduced into the literature by French geologist Alcide d'Orbigny in 1842.[3] The Kimmeridge Clay Formation takes 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 Tithonian is the uppermost stage of the Jurassic in the timescale of the ICS.[4]

The base of the Kimmeridgian is at the first appearance of ammonite species Pictonia baylei in the stratigraphic column.[5] 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.[5]

Subdivision

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

Palaeontology

Amphibians
Amphibians of the Kimmeridgian
Taxa Presence Location Description Images
Morrison Formation, Utah An extinct genus of cryptobranchoid salamander.

†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 from Wyoming
    • Mymoorapelta maysi
    		 Morrison Formation, Colorado, USA A poorly known early ankylosaurian.

    Birds
    Birds of the Kimmeridgian
    Taxa Presence Location Description Images
    • Archaeopteryx lithographica
    Life restoration of Archaeopteryx lithographica

    †Ornithopods
    Ornithopoda of the Kimmeridgian
    Taxa Presence Location Description Images
    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.
    Camptosaurus
    Othnielosaurus
    • Drinker

    †Plesiosaurs
    Plesiosaurs of the Kimmeridgian
    Taxa Presence Location Description Images
    Liopleurodon
    Bajocian-Tithonian

    †Sauropods
    †Sauropods of the Kimmeridgian
    Taxa Presence Location Description Images
    Europasaurus holgeri
    • Europasaurus holgeri
    Kimmeridge Clay Formation, England
    Morrison Formation, Colorado
    • "Ischyrosaurus" manseli
    		 Kimmeridge Clay Formation, Dorset, England The genus is preoccupied by a name Edward Drinker Cope coined in 1869.

    †Stegosaurs
    Stegosaurs of the Kimmeridgian
    Taxa Presence Location Description Images
    England and France 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.
    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
    Thalattosuchians of the Kimmeridgian
    Taxa Presence Location Description Images
    C. suevicus
    		 Germany A relatively small metriorhynchid genus.
    Dakosaurus, a marine crocodilian.
    Metriorhynchus, a marine crocodilian.
    D. maximus
    		 Germany A large metriorhynchid. The type species of the genus, Dakosaurus maximus, is known from Western Europe (England, France, Switzerland and Germany) of the Late Jurassic (Late Kimmeridgian-Early Tithonian).
    1. M. hugii
    2. M. mosae
    3. M. nowackianus
    4. M. buffetauti
    • M. hugii: Western Europe
    • M. mosae: France
    • M. nowackianus: Harrar, Ethiopia
    • M. buffetauti: Germany
    		 Machimosaurus hugii was the largest named teleosaurid and thalattosuchian up to its time, with an estimated length of approximately 7.2 metres
    1. M. nuyivijanan
    		 Sabinal Formation, Tlaxiaco Basin, Oaxaca, Mexico A metriorhynchid. It is the most basal genus of the Rhacheosaurini Tribe.
    1. M. geoffroyii
    2. M. hastifer
    		 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).
    1. T. carpenteri
    2. T. coryphaeus
    3. T. mexicanus
    		 Kimmeridge Clay Formation, Wiltshire, England; Oaxaca, Mexico

    †Theropods (non-avian)
    †Non-avian theropods of the Kimmeridgian
    Taxa Presence Location Description Images
    Allosaurus
    Ceratosaurus
    Coelurus
    Elaphrosaurus
    Lourinhanosaurus
    Marshosaurus
    Ornitholestes
    Tanycolagreus
    Torvosaurus
    • Aviatyrannis jurassica
    		 Guimarota Mine, Portugal Small 5 kg tyrannosauroid. Aviatyrannis along with Stokesosaurus represents the oldest known tyrannosauroids.
    • Coelurus fragilis
    		 Morrison Formation, Wyoming Small theropod about 2 metres in length
    • Elaphrosaurus bambergi
    		 Tendaguru Beds, Tanzania Probably a ceratosaur about 6 meters long
    • Fosterovenator churei
    		 Morrison Formation, Wyoming Probably a ceratosaur.
    Lourinhã Formation, Portugal A genus of medium sized carnivorous theropod dinosaurs. A basal tetanuran, might be an allosauroid, megalosauroid or a coelurosaur.
    • Marshosaurus bicentesimus
    		 Cleveland-Lloyd Quarry, Brushy Basin Member, Morrison Formation, Utah and possibly Colorado
    • Ornitholestes hermanni
    		 Bone Cabin Quarry, Morrison Formation, Wyoming Ornitholestes hermanni is a species of basal coelurosaurian theropod.
    • Saurophaganax maximus
    		 Morrison Formation, Oklahoma Possibly a species of Allosaurus but larger and much rarer than Allosaurus' type species. Estimated from 10.5 to 13 meters in length and from 3 to 4.5 metric tons in weight it's potentially the largest terrestrial predator of the Jurassic.
    • Tanycolagreus topwilsoni
    		 Morrison Formation, Wyoming Tanycolagreus is a genus of basal coelurosaurian theropod.
    • Torvosaurus tanneri
    • Torvosaurus gurneyi
    		 Torvosaurus was a very large megalosaurid predator, with an estimated maximum body length of 10 m (33 ft) and mass of 3.6–4.5 tonnes (4–5 short tons) for both its species, making Torvosaurus among the largest land carnivores of the Jurassic. Thomas Holtz estimated it at 12 meters (39 feet). Claims have been made indicating even larger sizes.

    Nautiloids
    Nautiloids of the Kimmeridgian
    Taxa Presence Location Description Images
    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
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    gollark: This is back in the heavy machinery architectures era.

    References

    Notes
    1. http://www.stratigraphy.org/index.php/ics-chart-timescale
    2. For a detailed version of the ICS' timescale, see Gradstein et al. (2004)
    3. Gradstein, F.M.; Ogg, J.G.; Schmitz, M.D.; Ogg, G.M. (editors) (2012). The Geologic Timescale 2012 (volume 1). Elsevier. p. 745. ISBN 978-0-44-459390-0.CS1 maint: uses authors parameter (link)
    4. INTERNATIONAL SUBCOMMISSION ON JURASSIC STRATIGRAPHY, Newsletter 31, Edited by Nicol Morton and Paul Bown, August 2004
    5. "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.
    6. 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. PMID 24598585.

    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.(in French)
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