|Subdivision of the Jurassic system
according to the IUGS, as of July 2012.
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.
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.
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:
- zone of Quenstedtoceras lamberti
- zone of Peltoceras athleta
- zone of Erymnoceras coronatum
- zone of Reineckeia anceps
- zone of Macrocephalites gracilis
- zone of Bullatimorphites bullatus
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.
|Crocodylomorphs of the Callovian|
|Junggarsuchus||The sphenosuchian Junggarsuchus was a small, ~1 meter long, Chinese predator.|
|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.|
|Ornithischia of the Callovian|
|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 primitive camptosaurid iguanodont, estimated to have been 3.5 meters long|
|Ferganocephale||Kyrgyzstan||Possibly an early pachycephalosaurid|
||Bathonian to Callovian||Lower Shaximiao Formation, Sichuan, China||A small ornithischian dinosaur distinguished from all other basal ornithischians by a single autapomorphy, the presence of a marked concavity that extends over the lateral surface of the postorbital.|
|Plesiosaurs of the Callovian|
|Sauropods of the Callovian|
|Abrosaurus||Abrosaurus was a small (30 foot adult length) sauropod from China with an unusual skull.|
||A Kyrgistani sauropod genus that resembled Rhoetosaurus.|
|Stegosaurs of the Callovian|
|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||Lisieux, France; Northern 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 of the Callovian|
|Eustreptospondylus||A moderately large (17–23 feet long) predatory dinosaur that was closely related to Megalosaurus.|
||An 11–13 foot predator from China whose discovery was assisted by the petroleum industry.|
|Yangchuanosaurus||A Chinese theropod. Specimens from this time period were formerly classed as a separate genus, Szechuanoraptor.|
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|
|Belemnites of the Callovian|
|Nautiloids of the Callovian|
|Neocoleoidea of the Callovian|
- See for a detailed geologic timescale Gradstein et al. (2004)
- Elmi & Babin fig.55.
- Salvador, Amos (1987). "Late Triassic‐Jurassic Paleogeography and Origin of Gulf of Mexico Basin". AAPG Bulletin 71 (4). pp. 419‐451. Retrieved 2011-03-09.
- Elmi, S. & Babin, C.; 2002: Histoire de la Terre, Dunod, Paris (2nd ed.), ISBN 2-10-006631-5. (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. (French)
- GeoWhen Database - Callovian
- Jurassic-Cretaceous timescale, at the website of the subcommission for stratigraphic information of the ICS
- Stratigraphic chart of the Upper Jurassic, at the website of Norges Network of offshore records of geology and stratigraphy
|Lower/Early Jurassic||Middle Jurassic||Upper/Late Jurassic|
|Hettangian | Sinemurian
Pliensbachian | Toarcian
|Aalenian | Bajocian
Bathonian | Callovian
|Oxfordian | Kimmeridgian