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The Late Devonian extinction consisted of several extinction events in the Late Devonian Epoch, which collectively represent one of five largest mass extinction events in the history of life on Earth. The term primarily refers to a major extinction, the Kellwasser event, which occurred around 372 million years ago, at the boundary between the Frasnian stage and the Famennian stage, the last stage in the Devonian Period. Overall, 19% of all families and 50% of all genera became extinct. A second mass extinction, the Hangenberg event, occurred 359 million years ago, bringing an end to the Famennian and Devonian, as the world transitioned into the Carboniferous Period.
The Eifelian is the first of two faunal stages in the Middle Devonian Epoch. It lasted from 393.3 ± 1.2 million years ago to 387.7 ± 0.8 million years ago. It was preceded by the Emsian Stage and followed by the Givetian Stage. The GSSP
Trimerocephalus is a genus of eyeless trilobites from the order Phacopida, family Phacopidae. It lived during the final stage of the Devonian, the Famennian, and became extinct at the end of this stage, together with all other trilobites with the exception of some Proetida. It can be found in Australia, the Czech Republic, France, Germany, Iran, Kazakhstan, Morocco, Poland, the Russian Federation (Urals), Spain, and the United Kingdom (England).
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 in the Devonian. It is usually considered the second-largest extinction in the Devonian Period, having occurred approximately 13 million years after the Late Devonian mass extinction at the Frasnian-Famennian boundary. The Hangenberg event was an anoxic event marked by a layer of black shale, and it has been proposed to have been related to a rapid sea-level fall from the last phase of the Devonian Southern Hemisphere glaciation. It has also been suggested to have been linked to an increase in terrestrial plant cover. That would have led to increased nutrient supply in rivers and may have led to eutrophication of semi-restricted epicontinental seas and could have stimulated algal blooms. However, support for a rapid increase in plant cover at the end of the Famennian is lacking. The event is named after the Hangenberg Shale, which is part of a sequence that straddles the Devonian-Carboniferous boundary in the Rhenish Massif of Germany.
The Late Silurian to Early Devonian Keyser Formation is a mapped limestone bedrock unit in Pennsylvania, Maryland, Virginia, and West Virginia.
Laccognathus embryi is an extinct species of porolepiform lobe-finned fish recovered from Ellesmere Island, Canada. It existed during the Frasnian age of the Late Devonian epoch.
Phoenixites is an early genus of the Falcitornoceratinae, a subfamily of the goniatitid Tornoceratidae family. This genus was named by Becker in 1995. The type species is "Tornoceras" frechi.
Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 2013.
The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull and the vertebral column, leading to the first craniates and vertebrates. The first fish lineages belong to the Agnatha, or jawless fish. Early examples include Haikouichthys. During the late Cambrian, eel-like jawless fish called the conodonts, and small mostly armoured fish known as ostracoderms, first appeared. Most jawless fish are now extinct; but the extant lampreys may approximate ancient pre-jawed fish. Lampreys belong to the Cyclostomata, which includes the extant hagfish, and this group may have split early on from other agnathans.
Cyrtospirifer is an extinct genus of brachiopods. The fossils are present in the Middle and Upper Devonian.
The Alexo Formation a stratigraphic unit of Late Devonian age. It is present on the western edge of the Western Canada Sedimentary Basin in the central Rocky Mountains and foothills of Alberta. The formation consists primarily of dolomite. It is locally fossiliferous and includes remains of marine animals such as brachiopods and conodonts.
Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 2016.
Polygnathus is an extinct genus of conodonts.
Icriodus is an extinct conodont genus in the family Gnathodontidae.
Alternognathus is an extinct conodont genus in the family Elictognathidae. An extensive study on its population dynamics and lifespan has recently been published.
Conodonts are an extinct class of animals whose feeding apparatuses called teeth or elements are common microfossils found in strata dating from the Stage 10 of the Furongian, the fourth and final series of the Cambrian, to the Rhaetian stage of the Late Triassic. These elements can be used alternatively to or in correlation with other types of fossils in the subfield of the stratigraphy named biostratigraphy.
Ancyrodella is an extinct genus of conodonts from the Late Devonian.
Siphonodella is an extinct genus of conodonts.
Cryptotaxis is an extinct genus of conodonts in the family Cryptotaxidae from the Famennian.
Diplacanthus is an extinct genus of Mid to Late Devonian fish in the class Acanthodii, known as spiny sharks.
References
- ↑ Zur Kenntnis der Conodonten-Fauna des europäischen Devons. 1. Die Gattung Palmatolepis. KJ Müller, 1956
- ↑ Disparity Changes in 370 Ma Devonian Fossils: The Signature of Ecological Dynamics? Girard C and Renaud S (2012), PLoS ONE, 7(4): e36230, doi : 10.1371/journal.pone.0036230
- ↑ Locality and horizon: Upper part of the Grey Member, Ferques Formation, La Parisienne quarry (now flooded), Pas-de-Calais, France. Specimen from lowermost Ag. triangularis Conodont Zone, equivalent to late Palmatolepis hassi Zone (ca. 373 Ma, Frasnian).
- Morphological variation of Palmatolepis Devonian conodonts: species versus genus. Catherine Girard, Sabrina Renaud and Aurélie Sérayet, Comptes Rendus Palevol, Volume 3, Issue 1, January 2004, Pages 1–8, doi : 10.1016/j.crpv.2003.09.008 (article in French)
- Shape Analysis of Frasnian Species of the Late Devonian Conodont Genus Palmatolepis. Gilbert Klapper and C. T. Foster, Jr., Memoir (The Paleontological Society), Vol. 32, Supplement to Vol. 67, no. 4 of the Journal of Paleontology (Jul., 1993), pages 1–35 (Stable URL, retrieved 2 May 2016)
