Olenekian

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).[2] The Olenekian is sometimes divided into the Smithian and the Spathian subages or substages.[3] The Olenekian follows the Induan and is followed by the Anisian (Middle Triassic).[4]

System/
Period		 Series/
Epoch		 Stage/
Age		 Age (Ma)
Jurassic Lower/
Early		 Hettangian younger
Triassic Upper/
Late		 Rhaetian 201.3 ~208.5
Norian ~208.5 ~227
Carnian ~227 ~237
Middle Ladinian ~237 ~242
Anisian ~242 247.2
Lower/
Early		 Olenekian 247.2 251.2
Induan 251.2 251.902
Permian Lopingian Changhsingian older
Subdivision of the Triassic system
according to the ICS, as of 2020.[1]

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.

Buntsandstein in Heligoland

Stratigraphic definitions

The Olenekian stage was introduced into scientific literature by Russian stratigraphers in 1956.[5] 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 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.

Olenekian life
The gymnosperm plant Voltzia heterophylla
Marine reptile Chaohusaurus

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.[6][7] 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.[8] However, transient metazoan reefs reoccurred during the Olenekian wherever permitted by environmental conditions.[9] Ammonoids and conodonts diversified, but both suffered losses during the Smithian-Spathian boundary extinction[10] at the end of the Smithian subage.

Ray-finned fishes largely remained unaffected by the Permian-Triassic extinction event.[11][12] 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 Sakamena Formation (Madagascar), Candelaria Formation (Nevada, United States), and Mikin Formation (Himachal Pradesh, India), and the Smithian aged assemblages of the Vikinghøgda Formation (Spitsbergen, Norway), Thaynes Formation (western United States), and Helongshan Formation (Anhui, China).

Marine temnospondyl amphibians, such as Aphaneramma or Wantzosaurus show wide geographic ranges during the Induan and Olenekian ages. Their fossils are found in Greenland, Spitsbergen, Pakistan and Madagascar.[13] The first marine reptiles appeared during the Olenekian.[13] 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.[14] This event was probably caused by late eruptions of the Siberian Traps and led to extinctions among several groups, especially nektonic and pelagic taxa such as ammonoids and conodonts. One of several exceptionally diverse Early Triassic assemblages, the Paris Biota[15] (from near Paris, southeast Idaho), was deposited in the wake of the Smithian-Spathian boundary extinction. 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.[16]

The Olenekian ammonoid Hedenstroemia

Cartilaginous fishes
Chondrichthyes of the Olenekian
Taxa Presence Location Description Images
Lopingian to Late Cretaceous Svalbard A hybodont elasmobranch
Hybodus
Listracanthus
Carboniferous to Early Triassic Canada A chondrichthyan with uncertain affinities, known primarily from their feather-like denticles.
Lopingian to Late Triassic United States A synechodontiform elasmobranch
Triassic Svalbard A hybodont elasmobranch
  • Pyknotylacanthus
 Early Triassic United States

Ray-finned fishes
Actinopterygii of the Olenekian
Taxa Presence Location Description Images
Triassic United States, Svalbard A non-neopterygian
Birgeria
Bobasatrania
Saurichthys
Lopingian to Middle Triassic Svalbard A non-neopterygian
Early Triassic Greenland, Madagascar A non-neopterygian
Early Triassic Svalbard A platysiagid
Early Triassic to Middle Triassic Svalbard A non-neopterygian
Triassic United States, Svalbard, China A non-neopterygian

Coelacanths
Actinistia of the Olenekian
Taxa Presence Location Description Images
Early Triassic Svalbard A coelacanth
Rebellatrix
Early Triassic Svalbard A coelacanth
Early Triassic Canada A fork-tailed coelacanth
Early Triassic Svalbard A coelacanth
Early Triassic Svalbard A coelacanth
Early Triassic Svalbard A coelacanth

Lungfishes
Dipnoi of the Olenekian
Taxa Presence Location Description Images
Early Triassic to Eocene Poland, Russia, Antarctica, Germany A ceratodontid dipnoan, a close relative of the extant Australian lungfish Neoceratodus.
Ceratodus
Gnathorhiza
Permian to Early Triassic Poland, Russia A gnathorhizid dipnoan
Early Triassic Australia
Early Triassic Russia

†Temnospondyls
Temnospondyli of the Olenekian
Taxa Presence Location Description Images
Early Triassic Svalbard A trematosaurid stereospondyl amphibian
Aphaneramma
Parotosuchus nasutus
Parotosuchus orenburgensis
Sclerothorax
Trematosaurus
Early Spathian Poland; Russia A brachyopid stereospondyl amphibian.
Induan to Smithian Madagascar A capitosaurian stereospondyl closely related to Watsonisuchus.
Early Triassic Germany A capitosaurian stereospondyl amphibian
Spathian Germany A capitosaurian stereospondyl amphibian
Early Triassic Europe; Central Asia A widespread and diverse genus of capitosaurian stereospondyl amphibian.
Late Spathian - Early Anisian Terrigal Formation, Australia A brachyopid stereospondyl amphibian.
Middle Triassic Africa; North America A capitosaurian stereospondyl amphibian
Germany A capitosaurian stereospondyl amphibian
Early Triassic Germany; Russia A trematosaurid stereospondyl amphibian
Late Vetlugian Russia A capitosaurian stereospondyl amphibian

†Chroniosuchians
Chroniosuchia of the Olenekian
Taxa Presence Location Description Images
Russia
Axitectum
Bystrowiana
Lopingian to Early Triassic Russia, China
Early Triassic Russia

Lissamphibia
Lissamphibians of the Induan
Taxa Presence Location Description Images
Poland Czatkobatrachus is an extinct genus of frog-like amphibians. It is, with Triadobatrachus, one of the two oldest known lissamphibians. More precisely, it is a member of Salientia; it is related to, but outside Anura, which includes all extant frogs.

†Procolophonomorphs
Procolophonomorpha of the Olenekian
Taxa Presence Location Description Images
Early Triassic Germany, Switzerland A genus of lizard-shaped parareptile
Sclerosaurus


Archosauromorphs
Archosauromorphs of the Olenekian
TaxaPresenceLocationDescriptionImages
Volgograd Oblast, Russia The oldest known tanystropheid.
Chasmatosuchus
Ctenosauriscus
Erythrosuchus
Garjainia
Prolacerta
Proterosuchus
Kolguyev Island, arctic Russia A basal archosauromorph reptile of controversial classification, various studies have considered it a close relative of Prolacerta, tanystropheids, both, or neither.
Lipovskaya Formation, Russia A ctenosauriscid suchian.
South Africa, China A proterosuchid that is one of the earliest well-known archosauriforms. It was over 2 meters (6 ft) long and is thought to have behaved like a modern crocodile. Its mouth had two distinct features: the top of its jaw hooked downwards to aid in holding prey, and the upper palate was lined with a row of teeth (a primitive feature lost in later archosaurs).
Solling Formation, Germany A ctenosauriscid suchian. Ctenosauriscus is one of the oldest archosaurs known to date.
Early Triassic Poland
250-237.2 Ma, Olenekian to Ladinian Omingonde Formation, Namibia
South Africa		 The largest erythrosuchid. One of its few distinguishing features other than its size is the smoothness of the margin of the squamosal. In other erythrosuchids, the margin of this bone projects backward from the skull, giving it a hook-like appearance. In Erythrosuchus, the margin is convex and lacks a hook.
247.3-245 Ma, Olenekian to Anisian Russia A potentially dubious archosauromorph of uncertain affinities. Initially believed to be a proterosuchid archosauriform, a 2016 analysis found that it also shared features with tanystropheids.
Russia An erythrosuchid approximately 1.50–2 meters (5–6 ft 8 in) long.
~252–247 Ma , Induan to Olenekian Katberg Formation, East Cape, South Africa Initially considered to be ancestral to modern lizards, a later study instead found that it shared more similarities with the lineage that would lead to archosaurs.
252-250 Ma, Induan to Olenekian South Africa
China		 A proterosuchid that was one of the largest land reptiles during the Early Triassic. It looked somewhat similar to a primitive crocodilian, and shared many of their modern features like long jaws, powerful neck muscles, short legs and a lengthy tail, while possessing several features unique to proterosuchids such as its hook-shaped mouth and long rows of simple cone-shaped teeth. This jaw may have been an adaptation for catching prey, such as Lystrosaurus.
Russia, Possibly a rauisuchid. Scythosuchus was between 2 and 3 metres long, and relatively heavily built.
Induan to Olenekian Knocklofty Formation, West Hobart, Tasmania Once believed to be a proterosuchid, this taxon is now believed to have been intermediate between advanced non-archosauriform archosauromorphs such as Prolacerta, and basal archosauriforms such as Proterosuchus. This genus is also notable being one of the most complete Australian Triassic reptiles known.
Induan to Olenekian Southern Urals, Russia Originally classified as a rauisuchid, Tsylmosuchus has more recently been interpreted as an indeterminate archosauriform. Tsylmosuchus occurred throughout the Olenekian age. Some of the strata from which Tsylmosuchus has been found are Induan in age, making it one of the earliest archosaurs.
latest Olenekian Yarenskian Gorizont, Komi Republic, Russia A genus of paracrocodylomorph archosaur, possibly a rauisuchid, and the oldest known archosaur from Russia.
Heshanggou Formation, China A ctenosauriscid suchian. Xilousuchus is one of the oldest archosaurs known to date.

Lepidosauromorphs
Lepidosauromorpha of the Olenekian
Taxa Presence Location Description Images
Early Triassic Poland


†Sauropterygia
Sauropterygians of the Olenekian
Taxa Presence Location Description Images
Late Olenekian United States, Wyoming A pistosaur.
Corosaurus
Olenekian China A possible pachypleurosaur.
Olenekian China A possible pachypleurosaur.

†Ichthyosauromorphs

†Hupehsuchians
†Hupehsuchia of the Olenekian
Taxa Presence Location Description Images
Early Triassic China An ichthyosauromorph
Hupehsuchus
Unnamed polydactylous hupehsuchian
Early Triassic China An ichthyosauromorph
Early Triassic China An ichthyosauromorph
Early Triassic China An ichthyosauromorph
Early Triassic China An ichthyosauromorph

†Ichthyosauriforms
†Ichthyosauriformes of the Olenekian
Taxa Presence Location Description Images
Early Triassic China An early ichthyosauriform
Cartorhynchus
Sclerocormus
Early Triassic China An early ichthyosauriform
†Ichthyopterygians
†Ichthyopterygia of the Olenekian
Taxa Presence Location Description Images
Early Triassic China
Chaohusaurus
Grippia
Omphalosaurus
Utatsusaurus
Early Triassic Canada, Japan, Greenland, China
Early Triassic to Middle Triassic Svalbard An early ichthyosauriform with button-like teeth
Early Triassic Svalbard
Early Triassic Miyagi Prefecture, Japan; British Columbia, Canada An early ichthyosauriform

Therapsids
Therapsids of the Olenekian
Taxa Presence Location Description Images
Kannemeyeria Burgersdorp Formation, South Africa
Ntawere Formation, Zambia
Omingonde Formation, Namibia
Manda Formation, Tanzania		 A kannemeyeriid that was one of the first representatives of the family, and hence one of the first large herbivores of the Triassic. Although it had a large head, it was lightweight due to the size of the eye sockets and nasal cavity. It also had limb girdles which formed massive plates of bone that helped support its heavily built body.
Lystrosaurus Fremouw Formation, Antarctica
Trirachodon Driekoppen Formation, Free State, South Africa
Omingonde Formation, Namibia
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References

Notes
  1. "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. 2020.
  2. According to Gradstein (2004). Brack et al. (2005) give 251 to 248 Ma
  3. Tozer E. T. (1965): Lower Triassic stages and ammonoid zones of Arctic Canada: Paper of the Geological Survey of Canada 65:1–14.
  4. See for a detailed geologic timescale Gradstein et al. (2004)
  5. Kiparisova & Popov (1956)
  6. 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.
  7. 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.
  8. 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.
  9. 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.
  10. 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.
  11. 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.
  12. 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. PMID 29315531.
  13. 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.
  14. 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.
  15. 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. PMID 28246643.
  16. Special issue on Paris Biota: https://www.sciencedirect.com/journal/geobios/vol/54

Literature

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