24 Facts About Devonian

Devonian is a geologic period and system of the Paleozoic, spanning 60.

Devonian palaeogeography was dominated by the supercontinent of Gondwana to the south, the small continent of Siberia to the north, and the medium-sized continent of Laurussia to the east.

The Devonian experienced several major mountain-building events as Laurussia and Gondwana approached; these include the Acadian Orogeny in North America and the beginning of the Variscan Orogeny in Europe.

The Great Devonian Controversy was a long period of vigorous argument and counter-argument between the main protagonists of Roderick Murchison with Adam Sedgwick against Henry De la Beche supported by George Bellas Greenough.

In nineteenth-century texts the Devonian has been called the "Old Red Age", after the red and brown terrestrial deposits known in the United Kingdom as the Old Red Sandstone in which early fossil discoveries were found.

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Devonian has erroneously been characterised as a "greenhouse age", due to sampling bias: most of the early Devonian-age discoveries came from the strata of western Europe and eastern North America, which at the time straddled the Equator as part of the supercontinent of Euramerica where fossil signatures of widespread reefs indicate tropical climates that were warm and moderately humid.

In fact the climate in the Devonian differed greatly during its epochs and between geographic regions.

Devonian Period is formally broken into Early, Middle and Late subdivisions.

Middle Devonian comprised two subdivisions: first the Eifelian, which then gave way to the Givetian.

Devonian was a relatively warm period, and probably lacked any glaciers for much of the period.

Devonian world involved many continents and ocean basins of various sizes.

The Devonian Period was a time of great tectonic activity, as the major continents of Laurussia and Gondwana drew closer together.

The tectonic effects of this collision continued into the Devonian, producing a string of mountain ranges along the southeastern coast of the continent.

Devonian reefs extended along the southeast edge of Laurussia, a coastline now corresponding to southern England, Belgium, and other mid-latitude areas of Europe.

The northwestern edge of Gondwana was an active margin for much of the Devonian, and saw the accretion of many smaller land masses and island arcs.

Nevertheless, they remained close enough to Gondwana that their Devonian fossils were more closely related to Australian species than to north Asian species.

At the beginning of the Devonian, Siberia was inverted relative to its modern orientation, but later in the period it moved northwards and began to twist clockwise, though it was still nowhere near its modern location.

Siberia approached the eastern edge of Laurussia as the Devonian progressed, but it was still separated by a seaway, the Ural Ocean.

Rheic Ocean, which separated Laurussia from Gondwana, was wide at the start of the Devonian, having formed after the drift of Avalonia away from Gondwana.

The great diversity of fish around at the time has led to the Devonian being given the name "The Age of Fish" in popular culture.

Devonian saw significant expansion in diversity of nektonic marine life driven by the abundance of planktonic microorganisms in the free water column as well as high ecological competition in benthic habitats, which were extremely saturated; this diversification has been labelled the Devonian Nekton Revolution by many researchers.

Many Early Devonian plants did not have true roots or leaves like extant plants although vascular tissue is observed in many of those plants.

Late Devonian extinction is not a single event, but rather is a series of pulsed extinctions at the Givetian-Frasnian boundary, the Frasnian-Famennian boundary, and the Devonian-Carboniferous boundary.

Reasons for the Late Devonian extinctions are still unknown, and all explanations remain speculative.