The Pragian is one of three faunal stages in the Early Devonian Epoch. It lasted from 410.8 ± 2.8 million years ago to 407.6 ± 2.8 million years ago. It was preceded by the Lochkovian Stage and followed by the Emsian Stage. The most important Lagerstätte of the Pragian is Rhynie chert in Scotland. It is named after the city of Prague.[7] The GSSP is located within the Prague Formation at Velká Chuchle, Prague.
| Pragian | |||||||||||||||||
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| Chronology | |||||||||||||||||
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| Etymology | |||||||||||||||||
| Name formality | Formal | ||||||||||||||||
| Name ratified | 1985[5] | ||||||||||||||||
| Usage information | |||||||||||||||||
| Celestial body | Earth | ||||||||||||||||
| Regional usage | Global (ICS) | ||||||||||||||||
| Time scale(s) used | ICS Time Scale | ||||||||||||||||
| Definition | |||||||||||||||||
| Chronological unit | Age | ||||||||||||||||
| Stratigraphic unit | Stage | ||||||||||||||||
| Time span formality | Formal | ||||||||||||||||
| Lower boundary definition | FAD of the conodonts Eognathodus sulcatus and Latericriodus steinachensis Morph beta | ||||||||||||||||
| Lower boundary GSSP | Velká Chuchle quarry, Prague, Czech Republic 50°00′53″N 14°22′21″E / 50.0147°N 14.3726°E | ||||||||||||||||
| Lower GSSP ratified | 1989[5] | ||||||||||||||||
| Upper boundary definition | FAD of the conodont Polygnathus kitabicus | ||||||||||||||||
| Upper boundary GSSP | Zinzil'ban Gorge, Uzbekistan 39°12′00″N 67°18′20″E / 39.2000°N 67.3056°E | ||||||||||||||||
| Upper GSSP ratified | 1995[6] | ||||||||||||||||
In North America the Pragian Stage is represented by Siegenian or Deerparkian time.
Pragian life
editThe first ammonoids (order Agoniatitida) appeared in later parts of this stage (at the lower boundary of the Zlichovian stage as it was known in Siberian representations). They were descended from bactritoid nautiloid ancestors, which also appeared in this stage before experiencing evolutionary radiations in the next stage.[8]
References
edit- ^ Kaufmann, B.; Trapp, E.; Mezger, K. (2004). "The numerical age of the Upper Frasnian (Upper Devonian) Kellwasser horizons: A new U-Pb zircon date from Steinbruch Schmidt(Kellerwald, Germany)". The Journal of Geology. 112 (4): 495–501. Bibcode:2004JG....112..495K. doi:10.1086/421077.
- ^ Algeo, T. J. (1998). "Terrestrial-marine teleconnections in the Devonian: links between the evolution of land plants, weathering processes, and marine anoxic events". Philosophical Transactions of the Royal Society B: Biological Sciences. 353 (1365): 113–130. doi:10.1098/rstb.1998.0195.
- ^ Parry, S. F.; Noble, S. R.; Crowley, Q. G.; Wellman, C. H. (2011). "A high-precision U–Pb age constraint on the Rhynie Chert Konservat-Lagerstätte: time scale and other implications". Journal of the Geological Society. 168 (4). London: Geological Society: 863–872. doi:10.1144/0016-76492010-043.
- ^ "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. September 2023. Retrieved December 16, 2024.
- ^ a b Chlupac, Ivo; Oliver, William (June 1989). "Decision on the Lochkovian-Pragian Boundary Stratotype (Lower Devonian)" (PDF). Episodes. 12 (2): 109–114. doi:10.18814/epiiugs/1989/v12i2/014. Retrieved 18 December 2020.
- ^ Yolkin, E.; Kim, A.; Weddige, K.; Talent, J.; House, M. (December 1997). "Definition of the Pragian/Emsian Stage boundary". Episodes. 20 (4): 235–240. doi:10.18814/epiiugs/1997/v20i4/005. Retrieved 18 December 2020.
- ^ "Pragian stage". Encyclopedia Britannica. Retrieved 2 October 2019.
- ^ Kröger, Björn (2009). "Nautiloids before and during the origin of ammonoids in a Siluro-Devonian section in the Tafilalt, Anti-Atlas, Morocco". Special Papers in Palaeontology. 79. ISBN 978-1-405-18770-1.
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