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In the geologic timescale, the Callovian is an age or stage in the Middle Jurassic, lasting between 166.1 ± 4.0 Ma (million years ago) and 163.5 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the Oxfordian.[2]

Stratigraphic definitions

The Callovian stage was first described by French palaeontologist Alcide d'Orbigny in 1852. Its name derives from the latinized name for Kellaways Bridge, a small hamlet 3 km north-east of Chippenham, Wiltshire, England.

The base of the Callovian is defined as the place in the stratigraphic column where the ammonite genus Kepplerites first appears, which is the base of the biozone of Macrocephalites herveyi. A global reference profile (a GSSP) for the base had in 2009 not yet been assigned.

The top of the Callovian (the base of the Oxfordian) is at the first appearance of ammonite species Brightia thuouxensis.

Subdivision

Matmor Formation (Callovian, Peltoceras athleta Zone) in Makhtesh Gadol, Israel.

The Callovian is often subdivided into three substages (or subages): Lower/Early, Middle and Upper/Late Callovian. In the Tethys domain, the Callovian encompasses six ammonite biozones:

Palaeogeography

During the Callovian, Europe was an Archipelago of a dozen or so large islands. Between them were extensive areas of continental shelf. Consequently, there are shallow marine Callovian deposits in Russia and from Belarus, through Poland and Germany, into France and eastern Spain and much of England. Around the former island coasts are frequently, land-derived sediments. These are to be found, for example, in western Scotland.[3]

The Louann Salt and the southern Campeche Salt of the Gulf of Mexico are thought to have formed by an embayment of the Pacific Ocean across modern-day Mexico.[4]

Palaeontology

Ankylosaurians

Ankylosauria of the Callovian
Taxa Presence Location Description Images

Sarcolestes

Oxford Clay Formation

a basal ankylosaurian known from a partial mandible


Crocodylomorphs

Crocodylomorphs of the Callovian
Taxa Presence Location Description Images
Junggarsuchus The sphenosuchian Junggarsuchus was a small, ~1 meter long, Chinese predator.
A life restoration of a Metriorhynchus species.
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 ft), although some individuals may have reached lengths rivaling those of large nile crocodiles.
Steneosaurus

†Marginocephalians and †Ornithopods

Marginocephalia and Ornithopoda of the Callovian
Taxa Presence Location Description Images
Agilisaurus Dashanpu Formation, Sichuan, China A 4-foot-long (1.2 m) bipedal herbivore that was built for speed. It was discovered in one of China's many Callovian deposits.
Callovosaurus England A dryosaurid iguanodont, estimated to have been 3.5 meters long
Ferganocephale Kyrgyzstan Possibly an early pachycephalosaurid
Hexinlusaurus Bathonian to Callovian Lower Shaximiao Formation, Sichuan, China A basal neornithischian
Xiaosaurus Bajocian-Callovian Shaximiao Formation, Sichuan, China A basal neornithischian

†Plesiosaurs

Plesiosaurs of the Callovian
Taxa Presence Location Description Images
Liopleurodon
Simolestes vorax
Pachycostasaurus
Peloneustes
Simolestes

†Sauropods

Sauropods of the Callovian
Taxa Presence Location Description Images
Abrosaurus Abrosaurus was a small (30 foot adult length) sauropod from China with an unusual skull.
Atlasaurus
"Bothriospondylus" madagascariensis
Cetiosauriscus
Ferganasaurus Kyrgyzstan
Jobaria Bathonian-Oxfordian Originally thought to have lived form the Hauterivian to Barremian
?Ornithopsis leedsi Originally placed with Ornithopsis hulkei, it is a species that requires its own genus.
Patagosaurus
Zigongosaurus Shaximiao Formation, Sichuan, China

†Stegosauria

Stegosaurs of the Callovian
Taxa Presence Location Description Images
Huayangosaurus Bathonian to Callovian Lower Shaximiao Formation, Sichuan, China A 4.5 meters in length quadrupedal herbivore with a small skull and a spiked tail. Bore the distinctive double row of plates, rising vertically along its arched back, of all the stegosaurians and two pairs of long spikes extending horizontally near the end of its tail
Lexovisaurus England Traditionally, Lexovisaurus was depicted as having either large spines over the hips or shoulders, with a selection of flat plates and round pointed spines that ran along the back and tail. It was probably about 5 m long.
Loricatosaurus France; England Known from remains previously assigned to Lexovisaurus.

Theropods

Theropods of the Callovian
Taxa Presence Location Description Images
Afrovenator Bathonian-Oxfordian Originally thought to have lived form the Hauterivian to Barremian
Eustreptospondylus A moderately large (17–23 feet long) predatory dinosaur that was closely related to Megalosaurus.
Gasosaurus An 11–13 foot predator from China whose discovery was assisted by the petroleum industry.
Pedopenna
Piatnitzkysaurus Cañadón Asfalto Formation, Argentina
Piveteausaurus Marnes de Dives Formation
Yangchuanosaurus A Chinese theropod. One specimen was at one time informally called "Szechuanoraptor".

†Ammonitida

Members of the Order Ammonitida are known as ammonitic ammonites. They are distinguished primarily by their suture lines. In ammonitic suture patterns, the lobes and saddles are much subdivided (fluted) and subdivisions are usually rounded instead of saw-toothed. Ammonoids of this type are the most important species from a biostratigraphical point of view. This suture type is characteristic of Jurassic and Cretaceous ammonoids but extends back all the way to the Permian.

Ammonites of the Callovian
Taxa Presence Location Description Images
Cadomites
Peltoceras solidum ammonite from the Matmor Formation (Jurassic, Callovian) in Makhtesh Gadol, Israel.
Oecoptychius
Oecotraustes
Oxycerites
Peltoceras

†Belemnites

Belemnites of the Callovian
Taxa Presence Location Description Images
Produvalia
Callovian belemnite from the Zohar Formation, northern Israel

Nautiloids

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

Neocoleoids

Neocoleoidea of the Callovian
Taxa Presence Location Description Images
Proteroctopus
Proteroctopus ribeti
Pyritized fossil ofRhomboteuthis lehmanifrom Voulte-sur-Rhône, France.
Pyritized fossil of Vampyronassa rhodanica from Voulte-sur-Rhône, France.
Rhomboteuthis
Rhomboteuthis lehmani
Vampyronassa
Vampyronassa rhodanica

References

  1. ^ http://www.stratigraphy.org/index.php/ics-chart-timescale
  2. ^ See for a detailed geologic timescale Gradstein et al. (2004)
  3. ^ Elmi & Babin fig.55.
  4. ^ Salvador, Amos (1987). "Late Triassic‐Jurassic Paleogeography and Origin of Gulf of Mexico Basin" (PDF). AAPG Bulletin. 71 (4). pp. 419‐451. Retrieved 2011-03-09. [permanent dead link]

Literature

  • Elmi, S. & Babin, C.; 2002: Histoire de la Terre, Dunod, Paris (2nd ed.), ISBN 2-10-006631-5. (in French)
  • Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
  • d'Orbigny, A.C.V.M.D.; 1842: Paléontologie française. 1. Terrains oolitiques ou jurassiques. 642 p, Bertrand, Paris. (in French)

External links