Oxfordian (stage)

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 2017.[1]

The Oxfordian is, in the ICS' geologic timescale, the earliest age of the Late Jurassic epoch, or the lowest stage of the Upper Jurassic series. It spans the time between 163.5 ± 4 Ma and 157.3 ± 4 Ma (million years ago). The Oxfordian is preceded by the Callovian and is followed by the Kimmeridgian.[2]

Stratigraphic definitions

Cyclically alternating limestone (light, more competent) and marl/clay layers of Oxfordian age at Péry-Reuchenette, near Tavannes, Jura Mountains, Switzerland.

The Oxfordian stage was called "Clunch Clay and Shale" by William Smith (1815–1816); in 1818 W. Buckland described them under the unwieldy title "Oxford, Forest or Fen Clay". The term Oxfordian was introduced by Alcide d'Orbigny in 1844. The name is derived from the English county of Oxford,[3] where the beds are well developed, but they crop out almost continuously from Dorsetshire to the coast of Yorkshire, generally forming low, broad valleys. They are well exposed at Weymouth, Oxford, Bedford, Peterborough, and in the cliffs at Scarborough, Red Cliff and Gristhorpe Bay. Rocks of this age are found also in Uig and Skye.[4]

The base of the Oxfordian stage is defined as the point in the stratigraphic record where the ammonite species Brightia thuouxensis first appears. A global reference profile for the base (a GSSP) had in 2009 not yet been assigned. The top of the Oxfordian stage (the base of the Kimmeridgian) is at the first appearance of ammonite species Pictonia baylei.

In the Tethys domain, the Oxfordian contains six ammonite biozones:

Palaeontology

†Sauropods

Sauropods of the Oxfordian
Taxa Presence Location Description Images
Bathonian-Oxfordian Originally thought to have lived form the Hauterivian to Barremian.

†Ornithischians

Ornithischians of the Oxfordian
Taxa Presence Location Description Images
Oxfordian? Tithonian? Chaoyang, Liaoning, China A marginocephalian dinosaur from the Late Jurassic of China, belonged to the Ceratopsia, a group of primarily herbivorous dinosaurs with parrot-like beaks
Chaoyangsaurus
Chialingosaurus
Chungkingosaurus
Dacentrurus
Tuojiangosaurus
Yinlong
Upper Shaximiao Formation, Sichuan, China A genus of stegosaur similar to Kentrosaurus
Upper Shaximiao Formation, Sichuan, China One of the smallest of the stegosaurids at 3–4 metres (9.8–13.1 ft) long, Chungkingosaurus had at least five spikes on its thagomizer. It had a rather high and narrow skull and large, thick bony plates.
England, France, Spain, Portugal A large stegosaurid
Dashanpu Formation, Sichuan, China By extrapolation from the remains of possible species and other basal ornithopods, it was a herbivorous bipedal animal around 1.3 to 1.5 meters (4.3 to 4.9 ft) long. It would have been a strong runner
Junggar Basin, Xinjiang, China A genus of stegosaurid
Upper Shaximiao Formation, Sichuan, China The best understood of the Chinese stegosaurs. It was around 7.0 meters (23.0 feet) long and 2 meters (6.6 feet) high, with a postulated weight of around 4 metric tons (4.4 short tons).
Shishugou Formation, Xinjiang, China A small, primarily bipedal herbivore, approximately 1.2 meters (3.9 feet) long, the oldest and most primitive ceratopsian known to science.

†Plesiosaurians

Plesiosaurians of the Oxfordian
Taxa Presence Location Description Images
Bajocian-Tithonian

†Thalattosuchians

Thalattosuchians of the Oxfordian
Taxa Presence Location Description Images
Metriorhynchus, a marine crocodilian.
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), although some individuals may have reached lengths rivaling those of large nile crocodiles.

Theropods

Theropoda of the Oxfordian
Taxa Presence Location Description Images
Bathonian-Oxfordian Originally thought to have lived form the Hauterivian to Barremian.
Yangchuanosaurus
Upper Shaximiao Formation, 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.
France one of the first dinosaurs collected and was the first described, though not named.
Upper Shaximiao Formation, Sichuan, China Yangchuanosaurus shangyouensis reached about 7 meters (23 feet) long with a skull around 80 cm (31 in) long. Its relative Y. magnus grew larger still: up to 10 meters (33 feet) long with a skull up to 1 metre (3.3 feet) in length. There was a bony knob on its nose and multiple hornlets and ridges, similar to Ceratosaurus. It had a massive tail that was about half its length.

Cephalopods

Cephalopods of the Oxfordian
Taxa Presence Location Description Images
Belemnite fossils
An illustration of a variety of fossil nautiloids.

References

Notes

  1. ↑ http://www.stratigraphy.org/index.php/ics-chart-timescale
  2. ↑ For a detailed geologic timescale see Gradstein et al. (2004)
  3. ↑ Oxfordian is a word meaning "from Oxford" (see wiktionary:Oxfordian).
  4. ↑  One or more of the preceding sentences incorporates text from a publication now in the public domain: Howe, John Allen (1911). "Oxfordian". In Chisholm, Hugh. Encyclopædia Britannica. 20 (11th ed.). Cambridge University Press. p. 415.

Literature

  • Brongniart, A.; 1829: Tableau théorique de la succession et de la disposition la plus générale on Europa, des terrains et roches, qui composent l'écorce de la terre, Paris.(in French)
  • Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
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