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[[File:Stadtroda Sandstein.jpg|thumb|230px|right|Sandstone from the Lower Triassic epoch]]
[[File:Stadtroda Sandstein.jpg|thumb|230px|right|Sandstone from the Lower Triassic epoch]]
[[File:Snider-Pellegrini Wegener fossil map.gif|thumb|right|230px|alt=Map showing where in the world fossils of this animal were found. It indicates that the animal's range extended to South Africa, India, and Antarctica. Other animals include a land reptile, swimming reptile, and a plant, and show that the continents were all joined together once.|Geographical distribution of ''Lystrosaurus'' {{colorbox|#a28170}} and contemporary fossils in [[Gondwana]].]]
[[File:Chasmatosaurus.jpg|thumb|230px|right|Proterosuchus, an early crocodile-type [[archosaur]]]]
[[File:Chasmatosaurus.jpg|thumb|230px|right|Proterosuchus, an early crocodile-type [[archosaur]]]]


The '''Lower Triassic''' is the first of three [[epoch (geology)|epoch]]s of the [[Triassic]] [[period (geology)|period]]. It lasted from about 252.17 million years ago (mya) to ~245 mya.<ref>International Chronostratigraphic Chart. [http://www.stratigraphy.org/ICSchart/ChronostratChart2013-01.pdf]</ref> The Lower Triassic is the oldest epoch of the [[Mesozoic]] [[era]]. These rocks were laid down just after the great [[Permian–Triassic extinction event]].
The '''Lower Triassic''' is the first of three [[epoch (geology)|epoch]]s of the [[Triassic]] [[period (geology)|period]]. It lasted from about 252.2 million years ago (mya) to ~247.2 mya. The Lower Triassic is the oldest epoch of the [[Mesozoic]] [[era]]. These rocks were laid down just after the great [[Permian–Triassic extinction event]].


The Lower Triassic was called the [[Scythian]] stage, which can be found in older literature. In Europe, most of the Lower Triassic is composed of [[sandstone]]. It is a [[lithostratigraphy|lithostratigraphic]] unit of [[continent]]al [[red beds]]. They were formed on land under [[desert]] conditions.
The Lower Triassic was called the [[Scythian]] stage, which can be found in older literature. In [[Europe]], most of the Lower Triassic is composed of [[sandstone]]. It is a [[stratigraphy|lithostratigraphic]] unit of [[continent]]al [[red beds]]. They were formed on land under [[desert]] conditions.


== Fauna ==
== Fauna ==

The massive extinctions that ended the [[Paleozoic]] [[era]] caused extreme hardship for the surviving species. Many types of [[coral]]s, [[brachiopod]]s, [[mollusca|molluscs]], [[echinoderm]]s, and other [[invertebrate]]s had completely disappeared. The most common hard-shelled marine invertebrates were [[bivalvia|bivalves]], [[gastropoda|gastropods]], [[ammonite]]s, [[sea urchin|echinoids]], and a few articulate [[brachiopod]]s. The most common land animal was the herbivorous [[synapsid]] ''[[Lystrosaurus]]''.
The massive extinctions that ended the [[Paleozoic]] [[era]] caused extreme hardship for the surviving species. Many types of [[coral]]s, [[brachiopod]]s, [[mollusca|molluscs]], [[echinoderm]]s, and other [[invertebrate]]s had completely disappeared. The most common hard-shelled marine invertebrates were [[bivalvia|bivalves]], [[gastropoda|gastropods]], [[ammonite]]s, [[sea urchin|echinoids]], and a few articulate [[brachiopod]]s. The most common land animal was the herbivorous [[synapsid]] ''[[Lystrosaurus]]''.


The earliest Triassic [[fauna]]s lacked [[biodiversity]] and were like that throughout the epoch. Recovery on land took 30 million years.<ref name="SahneyBenton2008RecoveryFromProfoundExtinction">{{ cite journal | url=http://journals.royalsociety.org/content/qq5un1810k7605h5/fulltext.pdf | author=Sahney S. and Benton M.J. | year=2008 | title=Recovery from the most profound mass extinction of all time | journal=Proceedings of the Royal Society: Biological | doi=10.1098/rspb.2007.1370 | volume = 275 | pages = 759–65|format=PDF | pmid=18198148 | issue=1636 | pmc=2596898}}</ref>
The earliest Triassic [[fauna]]s lacked [[biodiversity]] and were like that throughout the epoch. Recovery on land took 30 million years.<ref name="SahneyBenton2008RecoveryFromProfoundExtinction">{{ cite journal | url=https://dx.doi.org/10.1098/rspb.2007.1370 | author=Sahney S. and Benton M.J. | year=2008 | title=Recovery from the most profound mass extinction of all time | journal=Proceedings of the Royal Society: Biological | doi=10.1098/rspb.2007.1370 | volume = 275 | pages = 759–65| pmid=18198148 | issue=1636 | pmc=2596898}}</ref>


The first [[ichthyosaur]]s evolved in this epoch.
The first [[ichthyosaur]]s evolved in this epoch. The largest ichthyosaurs known come from the Triassic.


The climate during the Lower Triassic (especially in the interior of the supercontinent [[Pangaea]]) was generally dry. Deserts were widespread. The poles had a [[temperate climate]]. The relatively hot climate of the epoch may have been caused by widespread volcanic eruptions.
The climate during the Lower Triassic (especially in the interior of the supercontinent [[Pangaea]]) was generally dry. Deserts were widespread. The poles had a [[temperate climate]]. The relatively hot climate of the epoch may have been caused by widespread [[Volcano|volcanic]] eruptions.

On land, the plants included the [[lycophyte]]s, the dominant [[cycad]]ophytes, [[ginkgophyta]] (represented in modern times by ''[[Ginkgo biloba]]''), [[ferns]], [[horsetail]]s and [[glossopteris]].

[[File:Snider-Pellegrini Wegener fossil map.svg|center|450px|alt=Map showing where in the world fossils of this animal were found. It indicates that the animal's range extended to South Africa, India, and Antarctica. Other animals include a land reptile, swimming reptile, and a plant, and show that the continents were all joined together once.|Geographical distribution of ''Lystrosaurus'' {{colorbox|#a28170}} and contemporary fossils in [[Gondwana]].]]


== References ==
== References ==
{{Reflist}}
{{Reflist}}



{{Geologic History}}
{{Geologic History}}
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{{DEFAULTSORT:Triassic, Lower}}
{{DEFAULTSORT:Triassic, Lower}}
[[Category:Triassic]]
[[Category:Triassic]]

[[en:Early Triassic]]

Latest revision as of 09:23, 17 January 2023

Sandstone from the Lower Triassic epoch
Proterosuchus, an early crocodile-type archosaur

The Lower Triassic is the first of three epochs of the Triassic period. It lasted from about 252.2 million years ago (mya) to ~247.2 mya. The Lower Triassic is the oldest epoch of the Mesozoic era. These rocks were laid down just after the great Permian–Triassic extinction event.

The Lower Triassic was called the Scythian stage, which can be found in older literature. In Europe, most of the Lower Triassic is composed of sandstone. It is a lithostratigraphic unit of continental red beds. They were formed on land under desert conditions.

The massive extinctions that ended the Paleozoic era caused extreme hardship for the surviving species. Many types of corals, brachiopods, molluscs, echinoderms, and other invertebrates had completely disappeared. The most common hard-shelled marine invertebrates were bivalves, gastropods, ammonites, echinoids, and a few articulate brachiopods. The most common land animal was the herbivorous synapsid Lystrosaurus.

The earliest Triassic faunas lacked biodiversity and were like that throughout the epoch. Recovery on land took 30 million years.[1]

The first ichthyosaurs evolved in this epoch. The largest ichthyosaurs known come from the Triassic.

The climate during the Lower Triassic (especially in the interior of the supercontinent Pangaea) was generally dry. Deserts were widespread. The poles had a temperate climate. The relatively hot climate of the epoch may have been caused by widespread volcanic eruptions.

On land, the plants included the lycophytes, the dominant cycadophytes, ginkgophyta (represented in modern times by Ginkgo biloba), ferns, horsetails and glossopteris.

Map showing where in the world fossils of this animal were found. It indicates that the animal's range extended to South Africa, India, and Antarctica. Other animals include a land reptile, swimming reptile, and a plant, and show that the continents were all joined together once.
Geographical distribution of Lystrosaurus      and contemporary fossils in Gondwana.

References

[change | change source]
  1. Sahney S. and Benton M.J. (2008). "Recovery from the most profound mass extinction of all time". Proceedings of the Royal Society: Biological. 275 (1636): 759–65. doi:10.1098/rspb.2007.1370. PMC 2596898. PMID 18198148.