Emsian

From Wikipedia
https://en.wikipedia.org/wiki/Emsian
Emsian
407.6 ± 2.6 – 393.3 ± 1.2 Ma
Geology of Asia 400Ma.jpg
Paleogeography of the Emsian, 400 Ma
Chronology
Etymology
Name formalityFormal
Name ratified1985
Usage information
Celestial body Earth
Regional usageGlobal ( ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unit Age
Stratigraphic unit Stage
Time span formalityFormal
Lower boundary definitionFAD of the conodont Polygnathus kitabicus
Lower boundary GSSP Zinzil'ban Gorge, Uzbekistan
39°12′00″N 67°18′20″E / 39.2000°N 67.3056°E / 39.2000; 67.3056
GSSP ratified1995 [5]
Upper boundary definition FAD of the conodont Polygnathus costatus partitus
Upper boundary GSSP Wetteldorf Richtschnitt section, Wetteldorf, Eifel, Germany
50°08′59″N 6°28′18″E / 50.1496°N 6.4716°E / 50.1496; 6.4716
GSSP ratified1985 [6]

The Emsian is one of three faunal stages in the Early Devonian epoch. It lasted from 407.6 ± 2.6 million years ago to 393.3 ± 1.2 million years ago. It was preceded by the Pragian stage and followed by the Eifelian stage. It is named after the Ems river in Germany. [7] The GSSP is located in the Zinzil'ban Gorge in the Kitab State Geological Reserve of Uzbekistan, 35 centimetres (14 in) above the contact with the Madmon Formation.

Description

During this period, earliest known agoniatitid ammonoid fossils began appearing within this stage after first appearing in previous stage and began to evolutionarily radiate within this stage, in which a new ammonoid order Goniatitida rises in the end of Zlichovian stage (Siberian representation; corresponds to early Eifelian and after the end of Early Devonian, before 391.9 mya). [8] [9] Later agoniatitid ammonoids would die out in the Taghanic event in the upper middle Givetian. Goniatite ammonoids would give rise to further ammonoid orders, thus starting ammonoid dominance of marine fossils in further periods until their end at the Cretaceous-Paleogene mass extinction event.

In North America the Emsian Stage is represented by Sawkill or Sawkillian time.

Emsian geology

Emsian life

Agnathans

Agnathans of the Emsian
Taxa Presence Location Description Images
Drepanaspis Lochkovian-Emsian Hunsrück Slate, Germany, among others in Europe
Drepanaspis Fossil.jpg
Errivaspis Lochkovian-Emsian Wayne Hereford Quarry, England & Babin Sandstone, Podolia, Ukraine
Protaspis late Emsian Beartooth Butte Formation, Wyoming & Idaho, USA
Pteraspis Lochkovian- Eifelian Eifelian Maecuru Formation, Brazil; Lochkovian Ditton Group, Britain; Lochkovian Ivane Suite and Pragian Babin Sandstone, Ukraine
Estonian Museum of Natural History - Pteraspis.png

Placoderms

Placoderms of the Emsian
Taxa Presence Location Description Images
Gemuendina Hunsrück Slate, Germany
Gemuendina stuertzi.JPG

Osteichthyes

Bony fish of the Emsian
Taxa Presence Location Description Images
Amadeodipterus Mereenie Sandstone, Orange Peel Knob, Mount Winter, Australia An extinct genus of dipterid lungfish
Kenichthys Chuandong Formation, Yunnan province, China One of the most basal tetrapodomorph fish known. The genus is important to the study of the evolution of tetrapods due to the unique nature of its nostrils, which provide vital evidence regarding the evolutionary transition of fish-like nostrils to the vertebrate choanae
Luckeus Mereenie Sandstone, Orange Peel Knob, Mount Winter, Australia A genus of onychodontid lobe-finned fish
Muranjilepis Mereenie Sandstone, Orange Peel Knob, Mount Winter, Australia A basal tetrapodomorph fish in the family Osteolepidae

Arthropods

Arthropods of the Emsian
Taxa Presence Location Description Images
Jaekelopterus Pragian-early Emsian Klerf Formation, Rhineland, Germany
Wyoming[ citation needed]
Jaekelopterus rhenaniae reconstruction.jpg

References

  1. ^ 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. London: Geological Society. 168 (4): 863–872. doi: 10.1144/0016-76492010-043.
  2. ^ 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.
  3. ^ 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.
  4. ^ "Chart/Time Scale". www.stratigraphy.org. International Commission on Stratigraphy.
  5. ^ 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.
  6. ^ Ziegler, W.; Klapper, G. (June 1985). "Stages of the Devonian System" (PDF). Episodes. 8 (2): 104–109. doi: 10.18814/epiiugs/1985/v8i2/006. Retrieved 18 December 2020.
  7. ^ "Emsian stage". Encyclopedia Britannica. Retrieved 2 October 2019.
  8. ^ Klug, Christian (July 30, 1999). "Early Emsian ammonoids from the eastern Anti-Atlas (Morocco) and their succession". Paläontologische Zeitschrift. 74 (4): 479–515. doi: 10.1007/BF02988158.
  9. ^ Chlupac, I.; Lukes, P. (January 1999). "Pragian/Zlichovian and Zlichovian/Dalejan boundary sections in the Lower Devonian of the Barrandian Area, Czech Republic". ResearchGate. Retrieved June 26, 2018.