The Šilalė Event was an
extinction event
An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp fall in the diversity and abundance of multicellular organisms. It occ ...
affecting
conodonts
Conodonts, are an extinct group of marine jawless vertebrates belonging to the Class (biology), class Conodonta (from Ancient Greek κῶνος (''kōnos''), meaning "cone", and ὀδούς (''odoús''), meaning "tooth"). They are primarily known ...
during the
Přídolí
Přídolí () is a market town in Český Krumlov District in the South Bohemian Region of the Czech Republic. It has about 700 inhabitants.
Administrative division
Přídolí consists of eight municipal parts (in brackets population according to ...
, the final
stage
Stage, stages, or staging may refer to:
Arts and media Acting
* Stage (theatre), a space for the performance of theatrical productions
* Theatre, a branch of the performing arts, often referred to as "the stage"
* ''The Stage'', a weekly Brit ...
of the
Silurian
The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...
period.
Timing
The Šilalė Event, first identified in the
Milaičiai-103 core in southwestern
Lithuania
Lithuania, officially the Republic of Lithuania, is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea, bordered by Latvia to the north, Belarus to the east and south, P ...
, is marked by a negative carbon isotope excursion in carbonate rocks known as the Šilalė Negative Carbon Isotope Event.
This isotopic excursion is also known from the
Jočionys-299 borehole in eastern Lithuania, as well as in coeval deposits in the
Appalachian Basin
The geology of the Appalachians dates back more than 1.2 billion years to the Mesoproterozoic era when two continental cratons collided to form the supercontinent Rodinia, 500 million years prior to the development of the range during the form ...
of
North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
and has also been termed the Šilalė Low. The amplitudes of the ~405 Ka long eccentricity cycle were at their lowest point of the entire Přídolí during the Šilalė Event. The end of the Šilalė Event corresponds to the beginning of the ''Delotaxis detorta'' conodont biozone,
a conodont biozone once erroneously thought to have corresponded to the latest Přídolí.
Effects
The Šilalė Event resulted in a decline in conodont diversity and a corresponding increase not just in the diversity of
brachiopods
Brachiopods (), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the fron ...
but in their absolute abundance as well. After the event, conodont abundance surged during the interval of biotic recovery from the Šilalė mass rarity.
See also
*
Ireviken Event
The Ireviken event was the first of three relatively minor extinction events (the Ireviken, Mulde, and Lau events) during the Silurian period. It occurred at the Llandovery/ Wenlock boundary (mid Silurian, ). The event is best recorded at Irevik ...
*
Lundgreni Event
The Lundgreni Event, also known as the Mid-Homerian Biotic Crisis, was an extinction event during the middle Homerian age of the Silurian period. Evidence for the event has been observed in Silurian marine deposits in the Iberian Peninsula, Bohemia ...
*
Mulde Event
The Mulde event was an anoxic event, and marked the second of three relatively minor mass extinctions (the Ireviken, Mulde, and Lau events) during the Silurian period. It coincided with a global drop in sea level, and is closely followed by an ...
*
Lau Event
*
Kellwasser Event
The Late Devonian mass extinction, also known as the Kellwasser event, was a mass extinction event which occurred around 372 million years ago, at the boundary between the Frasnian and Famennian ages of the Late Devonian period.Racki, 2005McGhee, ...
*
Dasberg Event
*
Hangenberg Event
The Hangenberg event, also known as the Hangenberg crisis or end-Devonian extinction, is a mass extinction that occurred at the end of the Famennian stage, the last Stage (stratigraphy), stage in the Devonian Period (roughly 358.9 ± 0.4 million y ...
References
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Extinction events
Silurian