Olenekian


Olenekian
System Series Stage Age (Ma)
Jurassic Lower Hettangian younger
Triassic Upper Rhaetian 199.6–203.6
Norian 203.6–216.5
Carnian 216.5–228.0
Middle Ladinian 228.0–237.0
Anisian 237.0–245.0
Lower Olenekian 245.0–249.7
Induan 249.7–251.0
Permian Lopingian Changhsingian older
Subdivision of the Triassic system according to the IUGS, as of July 2009.

In the geologic timescale, the Olenekian is an age in the Early Triassic epoch or a stage in the Lower Triassic series. It spans the time between 249.7 ± 0.7 Ma and 245 ± 0.7 Ma (million years ago).[1] The Olenekian follows the Induan and is followed by the Anisian.[2]

The Olenekian saw the deposition of a large part of the Buntsandstein in Europe. Archosaurs - a group encompassing crocodiles, pterosaurs, dinosaurs, and ultimately birds - are diapsid reptiles that first evolved from Archosauriform ancestors during the Olenekian.

The Olenekian is roughly coeval with the regional Yongningzhenian stage used in China.

Contents

Stratigraphic definitions

The Olenekian stage was introduced into scientific literature by Russian stratigraphers in 1956.[3] The stage is named after Olenëk in Siberia. Before the subdivision in Olenekian and Induan became commongood, both stages formed the Skythian stage, which has since disappeared from the official timescale.

The base of the Olenekian is at the lowest occurrence of the ammonites Hedenstroemia or Meekoceras gracilitatis, and of the conodont Neospathodus waageni. It is defined as ending near the lowest occurrences of genera Japonites, Paradanubites, and Paracrochordiceras; and of the conodont Chiosella timorensis. A GSSP (global reference profile for the base) has in 2009 not yet been established.

The Olenekian is sometimes divided into the Smithian and the Spathian subages or substages.

Palaeontology

†Archosauromorphs (non-archosaurian)

Non-archosaurian Archosauromorphs of the Olenekian
Taxa Presence Location Description Images
Madygen, Kyrgyzstan

†Ichthyosaurs

†Ichthyosauria of the Olenekian
Taxa Presence Location Description Images
Japan, Canada

†Therapsids (non-mammalian)

Non-mammalian Therapsids of the Olenekian
Taxa Presence Location Description Images

See also

References

Notes

  1. ^ According to Gradstein (2004). Brack et al. (2005) give 251 to 248 Ma
  2. ^ See for a detailed geologic timescale Gradstein et al. (2004)
  3. ^ Kiparisova & Popov (1956)

Literature

  • Brack, P.; Rieber, H.; Nicora, A. & Mundil, R.; 2005: The Global boundary Stratotype Section and Point (GSSP) of the Ladinian Stage (Middle Triassic) at Bagolino (Southern Alps, Northern Italy) and its implications for the Triassic time scale, Episodes 28(4), pp. 233-244.
  • Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
  • Kiparisova, L.D. & Popov, J.N.; 1956: Расчленение нижнего отдела триасовой системы на ярусы (Subdivision of the lower series of the Triassic System into stages), Doklady Akademii Nauk SSSR 109(4), pp 842–845 (Russian).

External links

Triassic Period
Lower/Early Triassic Middle Triassic Upper/Late Triassic
Induan | Olenekian Anisian | Ladinian Carnian | Norian
Rhaetian