| 词条 | Emsian | ||||||||||||||||||||||||||||||
| 释义 |
The Emsian is one of three faunal stages in the Early Devonian epoch. It lasted from 407 ± 2.8 million years ago to 397.5 ± 2.7 million years ago. It was preceded by the Pragian stage and followed by the Eifelian stage. 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).[1][2] 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. PalaeontologyAgnathans
Placoderms
References1. ^{{Cite journal|title=Early Emsian ammonoids from the eastern Anti-Atlas (Morocco) and their succession|journal = Paläontologische Zeitschrift|volume = 74|issue = 4|pages = 479–515|last=Klug|first=Christian|date=July 30, 1999|doi=10.1007/BF02988158}} {{Geological history|p|p}}{{geochronology-stub}}2. ^{{Cite web|url=https://www.researchgate.net/publication/297492444|title=Pragian/Zlichovian and Zlichovian/Dalejan boundary sections in the Lower Devonian of the Barrandian Area, Czech Republic|last=Chlupac|first=I.|last2=Lukes|first2=P.|date=January 1999|website=ResearchGate|archive-url=|archive-date=|dead-url=|access-date=June 26, 2018}} 1 : Emsian |
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