Oxfordian (stage)


Oxfordian (stage)
System Series Stage Age (Ma)
Cretaceous Lower Berriasian younger
Jurassic Upper Tithonian 145.5–150.8
Kimmeridgian 150.8–155.7
Oxfordian 155.7–161.2
Middle Callovian 161.2–164.7
Bathonian 164.7–167.7
Bajocian 167.7–171.6
Aalenian 171.6–175.6
Lower Toarcian 175.6–183.0
Pliensbachian 183.0–189.6
Sinemurian 189.6–196.5
Hettangian 196.5–199.6
Triassic Upper Rhaetian older
Subdivision of the Jurassic system according to the IUGS, as of July 2009.

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 161.2 ± 4 Ma and 155.7 ± 4 Ma (million years ago). The Oxfordian is preceded by the Callovian and is followed by the Kimmeridgian.[1]

Contents

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 introduced into scientific writing by Alexandre Brongniart in 1827. The stage takes its name from the city of Oxford in England.

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:

  • zone of Epipeltoceras bimammatum
  • zone of Perishinctes bifurcatus
  • zone of Gregoryceras transversarium
  • zone of Perisphinctes plicatilis
  • zone of Cardioceras cordatum
  • zone of Quenstedtoceras mariae

Palaeontology

†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 long (10-13 ft), 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
Shishugou Formation, Xinjiang, China Either a hypsilophodont, or a less-derived ornithischian
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 long (4.3 to 4.9 ft). 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 ft) long and 2 meters (7 ft) 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 (4 ft) long, the oldest and most primitive ceratopsian known to science.

†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 (9.6 feet), although some individuals may have reached lengths rivaling those of large nile crocodiles.

Theropods

Theropoda of the Oxfordian
Taxa Presence Location Description Images
Upper Shaximiao Formation, Sichuan, China Yangchuanosaurus shangyouensis reached about 7 meters long (23 ft) with a skull around 80 cm long (32 in). Its relative Y. magnus grew larger still: up to 10 meters long (33 ft) with a skull up to 1 metre (3 ft) 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.
Upper Shaximiao Formation, China Monolophosaurus was a medium sized predator that grew to at least 5.7 meters (19 ft) long. It had an odd, unique crest on its head which ran most of the length of the skull.
Yangchuanosaurus

Nautiloids

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

†Belemnites

Belemnites of the Oxfordian
Taxa Presence Location Description Images
  • Produvalia
Belemnite fossils

References

Notes

  1. ^ For a detailed geologic timescale see Gradstein et al. (2004)

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.(French)
  • Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.

External links

Jurassic Period
Lower/Early Jurassic Middle Jurassic Upper/Late Jurassic
Hettangian | Sinemurian
Pliensbachian | Toarcian
Aalenian | Bajocian
Bathonian | Callovian
Oxfordian | Kimmeridgian
Tithonian

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