Dinopedia
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System (period) Series (epoch) Stage (age) Lower boundary, Ma
Cretaceous Lower Berriasian ~145
Jurassic Upper (Late) Tithonian 149.2±0.7
Kimmeridgian Golden spike154.8±0.8
Oxfordian 161.5±1.0
Middle Callovian 165.3±1.1
Bathonian Golden spike168.2±1.2
Bajocian Golden spike170.9±0.8
Aalenian Golden spike174.7±0.8
Lower (Early) Toarcian Golden spike184.2±0.3
Pliensbachian Golden spike192.9±0.3
Sinemurian Golden spike199.5±0.3
Hettangian Golden spike201.4±0.2
Triassic Upper Rhaetian older
Subdivisions and "golden spikes" according to IUGS as of September 2023[1]
220px-Péry-Reuchenette Oxfordian

The Oxfordian is a first stage of the Upper Jurassic series, corresponding to the Oxfordian age of the Late Jurassic epoch. It lasted from approximately 161.5 Ma to around 154.8 Ma (million years ago). It is preceded by the Callovian of the Middle Jurassic and is followed by the Kimmeridgian.

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

Definition[]

As of 2024, there is still no GSSP defining the base of the Oxfordian. The candidate is Thuoux Section in France with the First Appearing Datum (FAD) of the ammonite Brightia thuouxensis as the possible marker of the lower boundary of this stage.[2]

Oxfordian life[]

The ocean was inhabited by numerous cephalopods. Belemnites resembled squids, although unlike them they had hard internal rostras that were well preserved in the fossil record. Ammonites had the external and predominantly rounded shells, which protected them from the numerous predators of the time, sharks, ichthyosaurs (like Ophthalmosaurus), thalattosuchians and sauropterygians. In the Oxfordian strata of Oxford Clay Formation in the United Kingdom, belemnites (Belemnites, Belemnopsis), ammonites (Kosmoceras), bony (Lepidotus) and cartilaginous fish (Ischyodus, Orthybodus, Secarodus), metriorhynchids (Dakosaurus) and sauropterygians (Cryptoclidus) were found.

On land, the active evolution of dinosaurs continued. The largest herbivores were sauropods, and the earliest diplodocids likely appeared during the Oxfordian. Primitive diplodocids have been reported from Wyoming ("Amphicoelias brontodiplodocus") and the Republic of Georgia.

References[]

External links[]

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