Olenekian

From Wikipedia, the free encyclopedia
Olenekian
251.2 – 247.2 Ma
↓
Lange Anna, Helgoland.JPG
Olenekian Buntsandstein in Heligoland, Germany
Chronology
Etymology
Name formalityFormal
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitAge
Stratigraphic unitStage
Time span formalityFormal
Lower boundary definitionNot formally defined
Lower boundary definition candidatesFAD of the Conodont Neospathodus waageni
Lower boundary GSSP candidate section(s)Mud (Muth) village, Spiti valley, India[6]
Upper boundary definitionNot formally defined
Upper boundary definition candidates
Upper boundary GSSP candidate section(s)

In the geologic timescale, the Olenekian is an age in the Early Triassic epoch; in chronostratigraphy, it is a stage in the Lower Triassic series. It spans the time between 251.2 Ma and 247.2 Ma (million years ago).[7] The Olenekian is sometimes divided into the Smithian and the Spathian subages or substages.[8] The Olenekian follows the Induan and is followed by the Anisian (Middle Triassic).[9]

The Olenekian saw the deposition of a large part of the Buntsandstein in Europe. The Olenekian is roughly coeval with the regional Yongningzhenian Stage used in China.

Stratigraphic definitions[]

The Olenekian Stage was introduced into scientific literature by Russian stratigraphers in 1956.[10] The stage is named after Olenëk in Siberia. Before the subdivision in Olenekian and Induan became established, both stages formed the Scythian Stage, which has since disappeared from the official timescale.

The base of the Olenekian is at the lowest occurrence of the ammonoids Hedenstroemia or Meekoceras gracilitatis, and of the conodont Neospathodus waageni. It is defined as ending near the lowest occurrences of genera , , and ; and of the conodont Chiosella timorensis. A GSSP (global reference profile for the base) has not been established as of December 2020.

Olenekian life[]

Main page: Category:Olenekian life
The gymnosperm plant Voltzia heterophylla
Skull of the ray-finned fish Birgeria americana
Skull of the temnospondyl amphibian Trematosaurus brauni
Skull of the archosauromorph reptile Erythrosuchus

Life was still recovering from the severe end-Permian mass extinction. During the Olenekian, the flora changed from lycopod dominated (e.g. Pleuromeia) to gymnosperm and pteridophyte dominated.[11][12] These vegetation changes are due to global changes in temperature and precipitation. Conifers (gymnosperms) were the dominant plants during most of the Mesozoic. Among land vertebrates, the archosaurs - a group of diapsid reptiles encompassing crocodiles, pterosaurs, dinosaurs, and ultimately birds - first evolved from archosauriform ancestors during the Olenekian. This group includes ferocious predators like Erythrosuchus.

In the oceans, microbial reefs were common during the Early Triassic, possibly due to lack of competition with metazoan reef builders as a result of the extinction.[13] However, transient metazoan reefs reoccurred during the Olenekian wherever permitted by environmental conditions.[14] Ammonoids and conodonts diversified, but both suffered losses during the Smithian-Spathian boundary extinction[15] at the end of the Smithian subage.

Ray-finned fishes largely remained unaffected by the Permian-Triassic extinction event.[16][17] Many genera show a cosmopolitan (worldwide) distribution during the Induan and Olenekian (e.g. Australosomus, Birgeria, Parasemionotidae, Pteronisculus, Ptycholepidae, Saurichthys). This is well exemplified in the Griesbachian (early Induan) aged fish assemblages of the Wordie Creek Formation (East Greenland), the Dienerian (late Induan) aged assemblages of the (Madagascar), Candelaria Formation (Nevada, United States), and (Himachal Pradesh, India), and the Smithian aged assemblages of the Vikinghøgda Formation (Spitsbergen, Norway), Thaynes Formation (western United States), and (Anhui, China). Ray-finned fishes diversified during the Triassic and reached peak diversity during the Middle Triassic. This diversification is, however, obscured by a taphonomic megabias during the late Olenekian and early middle Anisian.[18]

Marine ichthyosauromorph reptile Chaohusaurus

Marine temnospondyl amphibians, such as the superficially crocodile-shaped trematosaurids Aphaneramma and Wantzosaurus, show wide geographic ranges during the Induan and Olenekian ages. Their fossils are found in Greenland, Spitsbergen, Pakistan and Madagascar.[19] Others, such as Trematosaurus, inhabited freshwater environments and were less widespread.

The first marine reptiles appeared during the Olenekian.[19] Hupehsuchia, Ichthyopterygia and Sauropterygia are among the first marine reptiles to enter the scene (e.g. Cartorhynchus, Chaohusaurus, Utatsusaurus, Hupehsuchus, Grippia, Omphalosaurus, Corosaurus). Sauropterygians and ichthyosaurs ruled the oceans during the Mesozoic Era.

A major extinction event occurred during the Olenekian: the Smithian-Spathian boundary extinction (SSBM).[15] This event was probably caused by late eruptions of the Siberian Traps, the same large igneous province whose eruptions were responsible for the Permian–Triassic extinction event approximately 2 myr earlier, which led to global warming. The SSBM led to extinctions among several groups, especially nektonic and pelagic taxa, such as ammonoids and conodonts. Prior to the SSBM extinction event, a flat gradient of latitudinal species richness is observed, suggesting that warmer temperatures extended into higher latitudes, allowing extension of geographic ranges of species adapted to warmer temperatures, and displacement or extinctions of species adapted to cooler temperatures.[20] The extinction event itself is associated with a sharp drop in global temperatures (ca. 8°C over a geologically short period).[21]

An example of an exceptionally diverse Early Triassic assemblage is the , fossils of which were discovered near Paris, Idaho[22] and other nearby sites in Idaho and Nevada.[23] The Paris Biota was deposited in the wake of the SSBM and it features at least 7 phyla and 20 distinct metazoan orders, including leptomitid protomonaxonid sponges (previously only known from the Paleozoic), thylacocephalans, crustaceans, nautiloids, ammonoids, coleoids, ophiuroids, crinoids, and vertebrates.[24] Such diverse assemblages show that organisms diversified wherever and whenever climatic an environmental conditions ameliorated.

References[]

Notes[]

  1. ^ Widmann, Philipp; Bucher, Hugo; Leu, Marc; et al. (2020). "Dynamics of the Largest Carbon Isotope Excursion During the Early Triassic Biotic Recovery". Frontiers in Earth Science. 8 (196): 1–16. doi:10.3389/feart.2020.00196.
  2. ^ McElwain, J. C.; Punyasena, S. W. (2007). "Mass extinction events and the plant fossil record". Trends in Ecology & Evolution. 22 (10): 548–557. doi:10.1016/j.tree.2007.09.003. PMID 17919771.
  3. ^ Retallack, G. J.; Veevers, J.; Morante, R. (1996). "Global coal gap between Permian–Triassic extinctions and middle Triassic recovery of peat forming plants". GSA Bulletin. 108 (2): 195–207. doi:10.1130/0016-7606(1996)108<0195:GCGBPT>2.3.CO;2. Retrieved 2007-09-29.
  4. ^ Payne, J. L.; Lehrmann, D. J.; Wei, J.; Orchard, M. J.; Schrag, D. P.; Knoll, A. H. (2004). "Large Perturbations of the Carbon Cycle During Recovery from the End-Permian Extinction". Science. 305 (5683): 506–9. doi:10.1126/science.1097023. PMID 15273391.
  5. ^ Ogg, James G.; Ogg, Gabi M.; Gradstein, Felix M. (2016). "Triassic". A Concise Geologic Time Scale: 2016. Elsevier. pp. 133–149. ISBN 978-0-444-63771-0.
  6. ^ "Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Retrieved 23 December 2020.
  7. ^ According to Gradstein (2004). Brack et al. (2005) give 251 to 248 Ma
  8. ^ Tozer E. T. (1965): Lower Triassic stages and ammonoid zones of Arctic Canada: Paper of the Geological Survey of Canada 65:1–14.
  9. ^ See for a detailed geologic timescale Gradstein et al. (2004)
  10. ^ Kiparisova & Popov (1956)
  11. ^ Schneebeli-Hermann, Elke; Kürschner, Wolfram M.; Kerp, Hans; Bomfleur, Benjamin; Hochuli, Peter A.; Bucher, Hugo; Ware, David; Roohi, Ghazala (April 2015). "Vegetation history across the Permian–Triassic boundary in Pakistan (Amb section, Salt Range)". Gondwana Research. 27 (3): 911–924. Bibcode:2015GondR..27..911S. doi:10.1016/j.gr.2013.11.007.
  12. ^ Goudemand, Nicolas; Romano, Carlo; Leu, Marc; Bucher, Hugo; Trotter, Julie A.; Williams, Ian S. (August 2019). "Dynamic interplay between climate and marine biodiversity upheavals during the early Triassic Smithian -Spathian biotic crisis". Earth-Science Reviews. 195: 169–178. Bibcode:2019ESRv..195..169G. doi:10.1016/j.earscirev.2019.01.013.
  13. ^ Foster, William J.; Heindel, Katrin; Richoz, Sylvain; Gliwa, Jana; Lehrmann, Daniel J.; Baud, Aymon; Kolar‐Jurkovšek, Tea; Aljinović, Dunja; Jurkovšek, Bogdan; Korn, Dieter; Martindale, Rowan C.; Peckmann, Jörn (20 November 2019). "Suppressed competitive exclusion enabled the proliferation of Permian/Triassic boundary microbialites". The Depositional Record. 6 (1): 62–74. doi:10.1002/dep2.97. PMC 7043383. PMID 32140241.
  14. ^ Brayard, Arnaud; Vennin, Emmanuelle; Olivier, Nicolas; Bylund, Kevin G.; Jenks, Jim; Stephen, Daniel A.; Bucher, Hugo; Hofmann, Richard; Goudemand, Nicolas; Escarguel, Gilles (18 September 2011). "Transient metazoan reefs in the aftermath of the end-Permian mass extinction". Nature Geoscience. 4 (10): 693–697. Bibcode:2011NatGe...4..693B. doi:10.1038/ngeo1264.
  15. ^ a b Galfetti, Thomas; Hochuli, Peter A.; Brayard, Arnaud; Bucher, Hugo; Weissert, Helmut; Vigran, Jorunn Os (2007). "Smithian-Spathian boundary event: Evidence for global climatic change in the wake of the end-Permian biotic crisis". Geology. 35 (4): 291. Bibcode:2007Geo....35..291G. doi:10.1130/G23117A.1.
  16. ^ Romano, Carlo; Koot, Martha B.; Kogan, Ilja; Brayard, Arnaud; Minikh, Alla V.; Brinkmann, Winand; Bucher, Hugo; Kriwet, Jürgen (February 2016). "Permian-Triassic Osteichthyes (bony fishes): diversity dynamics and body size evolution". Biological Reviews. 91 (1): 106–147. doi:10.1111/brv.12161. PMID 25431138. S2CID 5332637.
  17. ^ Smithwick, Fiann M.; Stubbs, Thomas L. (2 February 2018). "Phanerozoic survivors: Actinopterygian evolution through the Permo‐Triassic and Triassic‐Jurassic mass extinction events". Evolution. 72 (2): 348–362. doi:10.1111/evo.13421. PMC 5817399. PMID 29315531.
  18. ^ Romano, Carlo (January 2021). "A Hiatus Obscures the Early Evolution of Modern Lineages of Bony Fishes". Frontiers in Earth Science. 8: 618853. doi:10.3389/feart.2020.618853.
  19. ^ a b Scheyer, Torsten M.; Romano, Carlo; Jenks, Jim; Bucher, Hugo; Farke, Andrew A. (19 March 2014). "Early Triassic Marine Biotic Recovery: The Predators' Perspective". PLOS ONE. 9 (3): e88987. Bibcode:2014PLoSO...988987S. doi:10.1371/journal.pone.0088987. PMC 3960099. PMID 24647136.
  20. ^ Brayard, Arnaud; Bucher, Hugo; Escarguel, Gilles; Fluteau, Frédéric; Bourquin, Sylvie; Galfetti, Thomas (September 2006). "The Early Triassic ammonoid recovery: paleoclimatic significance of diversity gradients". Palaeogeography, Palaeoclimatology, Palaeoecology. 239 (3–4): 374–395. Bibcode:2006PPP...239..374B. doi:10.1016/j.palaeo.2006.02.003.
  21. ^ Goudemand, Nicolas; Romano, Carlo; Leu, Marc; Bucher, Hugo; Trotter, Julie A.; Williams, Ian S. (August 2019). "Dynamic interplay between climate and marine biodiversity upheavals during the early Triassic Smithian -Spathian biotic crisis". Earth-Science Reviews. 195: 169–178. Bibcode:2019ESRv..195..169G. doi:10.1016/j.earscirev.2019.01.013.
  22. ^ Brayard, Arnaud; Krumenacker, L. J.; Botting, Joseph P.; Jenks, James F.; Bylund, Kevin G.; Fara, Emmanuel; Vennin, Emmanuelle; Olivier, Nicolas; Goudemand, Nicolas; Saucède, Thomas; Charbonnier, Sylvain; Romano, Carlo; Doguzhaeva, Larisa; Thuy, Ben; Hautmann, Michael; Stephen, Daniel A.; Thomazo, Christophe; Escarguel, Gilles (15 February 2017). "Unexpected Early Triassic marine ecosystem and the rise of the Modern evolutionary fauna". Science Advances. 3 (2): e1602159. Bibcode:2017SciA....3E2159B. doi:10.1126/sciadv.1602159. PMC 5310825. PMID 28246643.
  23. ^ Smith, Christopher P.A.; Laville, Thomas; Fara, Emmauel; Escarguel, Gilles; Olivier, Nicolas; Vennin, Emmanuelle; Goudemand, Nicolas; Bylund, Kevin G.; Jenks, James F.; Stephen, Daniel A.; Hautmann, Michael; Charbonnier, Sylvain; Krumenacker, L. J.; Brayard, Arnaud (4 October 2021). "Exceptional fossil assemblages confirm the existence of complex Early Triassic ecosystems during the early Spathian". Scientific Reports. 11: 19657. doi:10.1038/s41598-021-99056-8. PMID 34608207.
  24. ^ Special issue on Paris Biota: https://www.sciencedirect.com/journal/geobios/vol/54

Literature[]

External links[]

Coordinates: 31°57′55″N 78°01′29″E / 31.9653°N 78.0247°E / 31.9653; 78.0247

Retrieved from ""