Callovian

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.[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 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:

• zone of Quenstedtoceras lamberti
• zone of Peltoceras athleta
• zone of Erymnoceras coronatum
• zone of Reineckeia anceps
• zone of Macrocephalites gracilis
• zone of Bullatimorphites bullatus

Palaeogeography

Callovian rocks of the Osgodby Formation[3] at Cayton Bay in North Yorkshire, England

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.[4]

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.[5]

Palaeontology

Amphibians

Amphibians of the Oxfordian
Taxa	Presence	Location	Description	Images
Gobiops		China; Mongolia; Russia	Gobiops desertus was a brachyopid temnospondyl.

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 Junggarsuchus sloani			The sphenosuchian Junggarsuchus was a small, ~1 meter long, Chinese predator.	A life restoration of a Metriorhynchus species. Suchodus durobrivensis
Metriorhynchus Metriorhynchus geoffroyii Metriorhynchus superciliosus			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 Steneosaurus rostromajor			A dubious taxon of teleosaurid thalattosuchian. The genus has been used as a wastebasket taxon for thalattosuchian fossils for over two centuries, and almost all known historical species of teleosauroid have been included within it at one point.
Suchodus Suchodus durobrivensis Suchodus brachyrhynchus			A metriorhynchid thalattosuchian. Formerly thought as a species of Metriorhynchus, it's now recognised as the most basal member of the subfamily Geosaurinae.
Tyrannoneustes Tyrannoneustes lythrodectikos			A large metriorhynchid thalattosuchian in the subfamily Geosaurinae.

†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.	Agilisaurus
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
Borealonectes		Canada	A rhomaleosaurid.	Cryptoclidus Muraenosaurus Liopleurodon Peloneustes Simolestes vorax
Cryptoclidus		England	A long-necked plesiosauroid plesiosaur.
Marmornectes		England	A longirostrine pliosaurid.
Muraenosaurus		England	A long-necked plesiosauroid plesiosaur that reached over 5 meters in lentgh.
Liopleurodon		England	A large pliosaurid.
Pachycostasaurus		England	A pliosaurid. It was most likely a benthic predator.
Peloneustes		England	A small fast pliosaurid adapted to hunting fast swimming and hard prey like ammonites.
Picrocleidus		England	A long-necked plesiosauroid plesiosaur.
"Pliosaurus" andrewsi		England	Originally described as a species of the later living Pliosaurus, it is now considered a more basal pliosaurid.
Simolestes Simolestes vorax		England	A cephalopod hunting pliosaurid measuring around 4.5 m in length.
Tricleidus		England	A long-necked plesiosauroid plesiosaur.

†Sauropods

Sauropods of the Callovian
Taxa	Presence	Location	Description	Images
Abrosaurus	Bathonian or Callovian	Shaximiao Formation,  China	An 11 m (36 ft) macronarian with enlarged nostrils. Known from only a skull.[6]
Bellusaurus	late Callovian	Shishugou Formation,  China	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.[6]
"Bothriospondylus" madagascariensis
Cetiosauriscus	Callovian	Oxford Clay Formation,  England	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.[6]
Chebsaurus	Callovian	unnamed formation,  Algeria	A juvenile sauropod known from two incomplete partial skeletons.[6]
Datousaurus	Bathonian or Callovian	Shaximiao Formation,  China	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.[6]
Dystrophaeus	Callovian or Oxfordian	Summerville Formation,  Utah	A 13 m (43 ft) incompletely known sauropod of uncertain relationships.[6]
Ferganasaurus	Callovian	Balabansai Formation,  Kyrgyzstan	An 18 m (59 ft) incompletely known sauropod claimed to have two hand claws.[6]
Jobaria	Callovian or Oxfordian	Tiouraren Formation,  Niger	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.[6]
Omeisaurus	Bathonian or Callovian to Oxfordian	Shaximiao Formation,  China	A 14 to 18 m (46 to 59 ft) mamenchisaurid known from multiple species of differing sizes and ages. All have very long necks.[6]
?Ornithopsis leedsi			Originally placed with Ornithopsis hulkei, it is a species that requires its own genus.
Patagosaurus	Middle Jurassic	Canadon Asfalto Formation,  Argentina	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.[6]
Shunosaurus	Bathonian or Callovian	Shaximiao Formation,  China	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.[6]
Zigongosaurus		Shaximiao Formation,  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	Huayangosaurus Lexovisaurus
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	Tiourarén Formation, Niger	A large megalosaurid theropod 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	Afrovenator. Chuandongocoelurus. Eustreptospondylus. Gasosaurus Kaijiangosaurus. Monolophosaurus Piatnitzkysaurus. Spinostropheus. Xuanhanosaurus. Yangchuanosaurus
Chuandongocoelurus	Bathonian- Callovian	Lower Shaximiao Formation, Sichuan, China	A predatory 4 meters long basal tetanuran theropod.
Eustreptospondylus			A medium-sized (20 feet long) predatory dinosaur that was closely related to Megalosaurus.
Gasosaurus	Bathonian- Callovian	Lower Shaximiao Formation, Sichuan, China	An 11–13 foot predator from China whose discovery was assisted by the petroleum industry. It may be the most basal coelurosaurian yet known, a carnosaur or may even be close to the common ancestor of the two groups.
Kaijiangosaurus	Bathonian- Callovian	Lower Shaximiao Formation, Sichuan, China	A predatory basal tetanuran theropod about 5 meters long. Might be the same as Gasosaurus.
Monolophosaurus		Wucaiwan Member, Shishugou Formation, Xinjiang, China	Monolophosaurus was a medium-sized predator that grew to at least 5 meters (16 feet) long. It had an odd, unique crest on its head which ran most of the length of the skull.
Pedopenna		Daohugou Beds, Tiaojishan Formation, China	A small, feathered, maniraptoran dinosaur from China.
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	A very large megalosaurid with a possible length of 11 meters.
Spinostropheus	Bathonian-Oxfordian	Tiourarén Formation, Niger	A medium sized ceratosaurian.
Streptospondylus	Late Callovian	Normandy, France	It was a medium-sized tetanuran theropod, possibly a megalosauroid, with an estimated length of 6 meters.
Wiehenvenator		Pott quarry, Wiehen Hills, Westphalia	A very large, derived megalosaurid closely related to Torvosaurus. Though during its original discovery it was speculated to be among the largest theropods to ever live, later estimations concluded more moderate sizes.
Xuanhanosaurus		Lower Shaximiao Formation, Sichuan, China	A predatory basal tetanuran theropod about 5 meters long. Might be a primitive megalosaur or the most primitive metriacanthosaurid.
Yangchuanosaurus shangyouensis	Bathonian- Callovian	Upper Shaximiao Formation, Sichuan, China	A large allosauroid theropod from China, that could grow over 10 meters long and 3 tonnes of weight . Specimens once assigned to Yangchuanosaurus magnus and the specimen informally called "Szechuanoraptor" most likely belong in this species.

†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. http://www.bgs.ac.uk/lexicon/lexicon.cfm?pub=OSBY
4. Elmi & Babin fig.55.
5. 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.
6. Paul, G.S. (2016). The Princeton Field Guide to Dinosaurs (2nd ed.). Princeton University Press. pp. 1–360. ISBN 978-0-691-16766-4.

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

• 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