|Subdivision of the Jurassic system|
according to the ICS, as of 2017.
In the geologic timescale, the Callovian is an age and 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:
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.
|Ankylosauria of the Callovian|
a basal ankylosaurian known from a partial mandible
|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.|
†Marginocephalians and †OrnithopodsEdit
|Marginocephalia and Ornithopoda 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 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 of the Callovian|
|Sauropods of the Callovian|
|Abrosaurus||Bathonian or Callovian||Shaximiao Formation,
|An 11 m (36 ft) macronarian with enlarged nostrils. Known from only a skull.|
|Bellusaurus||late Callovian||Shishugou Formation,
|A 13 m (43 ft) titanosauriform with a long neck, shoulders higher than hips and a short tail. Klamelisaurus has been thought to be the adult of the genus.|
|Cetiosauriscus||Callovian||Oxford Clay Formation,
|A 15 m (49 ft) "cetiosaur" sauropod with long arms and a moderately long tail. Known from a partial skeleton once thought to be a diplodocoid.|
|A juvenile sauropod known from two incomplete partial skeletons.|
|Datousaurus||Bathonian or Callovian||Shaximiao Formation,
|A 10 m (33 ft) "cetiosaur" sauropod with a moderately long neck and an shoulder higher than hip. Known from a partial skull and skeletons, a high browser.|
|Dystrophaeus||Callovian or Oxfordian||Summerville Formation,
|A 13 m (43 ft) incompletely known sauropod of uncertain relationships.|
|An 18 m (59 ft) incompletely known sauropod claimed to have two hand claws.|
|Jobaria||Callovian or Oxfordian||Tiouraren Formation,
|A 16 m (52 ft) macronarian with a narrow head, short neck, moderately long tail and long hand and arm. Originally thought to be from the Early Cretaceous, relationships of Jobaria are uncertain.|
|Omeisaurus||Bathonian or Callovian to Oxfordian||Shaximiao Formation,
|A 14 to 18 m (46 to 59 ft) mamenchisaurid known from multiple species of differing sizes and ages. All have very long necks.|
|?Ornithopsis leedsi||Originally placed with Ornithopsis hulkei, it is a species that requires its own genus.|
|Patagosaurus||Middle Jurassic||Canadon Asfalto Formation,
|A 16.5 m (54 ft) "cetiosaur" sauropod with a short, rounded skull, moderately long neck, long tail, and long arms. Known from multiple skeletons and parts of the skull, with a tail allowing rearing for high browsing.|
|Shunosaurus||Bathonian or Callovian||Shaximiao Formation,
|A 9.5 m (31 ft) "cetiosaur" sauropod with a short neck, long legs and a tail with spikes on the end. Known from many skeletons and skulls, a medium-height browser with a defensive tail club.|
|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||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|
|Afrovenator||Bathonian-Oxfordian||reaching 8 meters (26 feet) long, Afrovenator was discovered in what is now Niger. It was also thought to have lived from the Hauterivian to Barremian of the Early Cretaceous|
|Eustreptospondylus||A medium-sized (20 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.|
|Piatnitzkysaurus||Cañadón Asfalto Formation, Argentina||Piatnitzkysaurus was 11-13 feet long and was the first megalosaur to live in South America.|
|Piveteausaurus||Marnes de Dives Formation|
|Yangchuanosaurus||A Chinese theropod. One specimen was at one time informally called "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" (PDF). AAPG Bulletin. 71 (4). pp. 419‐451. Retrieved 2011-03-09.[permanent dead link]
- Paul, G.S. (2016). The Princeton Field Guide to Dinosaurs (2nd ed.). Princeton University Press. pp. 1–360. ISBN 978-0-691-16766-4.
- 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)