Norian

The Norian is a division of the Triassic geological period. It has the rank of an age (geochronology) or stage (chronostratigraphy). The Norian lasted from ~227 to 208.5 million years ago.[2] It was preceded by the Carnian and succeeded by the Rhaetian.[3]

System/
Period
Series/
Epoch
Stage/
Age
Age (Ma)
Jurassic Lower/
Early
Hettangian younger
Triassic Upper/
Late
Rhaetian 201.3 ~208.5
Norian ~208.5 ~227
Carnian ~227 ~237
Middle Ladinian ~237 ~242
Anisian ~242 247.2
Lower/
Early
Olenekian 247.2 251.2
Induan 251.2 251.902
Permian Lopingian Changhsingian older
Subdivision of the Triassic system
according to the ICS, as of 2018.[1]

Stratigraphic definitions

Otisk stopy ceskeho dinosaura
Cast of a tridactyl footprint of a theropod dinosaur from the Norian of the Czech Republic.

The Norian was named after the Noric Alps in Austria. The stage was introduced into scientific literature by Austrian geologist Edmund Mojsisovics von Mojsvar in 1869.

The Norian stage begins at the base of the ammonite biozones of Klamathites macrolobatus and Stikinoceras kerri, and at the base of the conodont biozones of Metapolygnathus communisti and Metapolygnathus primitius. A global reference profile for the base (a GSSP) had in 2009 not yet been appointed.

The top of the Norian (the base of the Rhaetian) is at the first appearance of ammonite species Cochloceras amoenum. The base of the Rheatian is also close to the first appearance of conodont species Misikella spp. and Epigondolella mosheri and the radiolarid species Proparvicingula moniliformis.

In the Tethys domain, the Norian stage contains six ammonite biozones:

  • zone of Halorites macer
  • zone of Himavatites hogarti
  • zone of Cyrtopleurites bicrenatus
  • zone of Juvavites magnus
  • zone of Malayites paulckei
  • zone of Guembelites jandianus

Palaeontology

Archosauromorphs

Archosauromorphss of the Norian
Taxa Presence Location Description Images

Löwenstein Formation; Trossingen Formation, both in Germany; Huai Hin Lat, Thailand; Fleming Fjord Formation, Greenland

Archosaurs

Archosaurs of the Ladinian
Taxa Presence Location Description Images
All across Europe Zanclodon is the name formally used for fossil material that might actually belongs to at least two genera of dinosaur from the Late Triassic among other genera.

†Ichthyosaurs

†Placodonts

Mammalia

Temnospondyls

†Ammonites

Pinacoceras layeri norian
Pinacoceras layeri

References

Notes

  1. ^ "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. 2018.
  2. ^ According to Gradstein et al. (2004). Brack et al. (2005) give 226 to 207 million years
  3. ^ See for a detailed geologic timescale Gradstein et al. (2004)
  4. ^ The genera listed are included in Mammalia by Kielan-Jaworowska et al. (2004) but not by those who restrict the taxon to the crown group.

Literature

  • Brack, P.; Rieber, H.; Nicora, A. & Mundil, R.; 2005: The Global boundary Stratotype Section and Point (GSSP) of the Ladinian Stage (Middle Triassic) at Bagolino (Southern Alps, Northern Italy) and its implications for the Triassic time scale, Episodes 28(4), pp. 233–244.
  • Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
  • Kielan-Jaworowska, Z.; Cifelli, R. L.; Luo, Zhe-Xi; 2004: Mammals from the Age of Dinosaurs, Columbia University Press.
  • Martz, J.W.; 2008: Lithostratigraphy, chemostratigraphy, and vertebrate biostratigraphy of the Dockum Group (Upper Triassic), of southern Garza County, West Texas, Doctoral Dissertation, Texas Tech.

External links

Anomura

Anomura (sometimes Anomala) is a group of decapod crustaceans, including hermit crabs and others. Although the names of many anomurans includes the word crab, all true crabs are in the sister group to the Anomura, the Brachyura (the two groups together form the clade Meiura).

Coloradisaurus

Coloradisaurus (meaning "Colorados [from Los Colorados Formation] lizard") is a genus of massospondylid sauropodomorph dinosaur. It lived during the Late Triassic period (Norian to Rhaetian stages) in what is now La Rioja Province, Argentina. It is known from the holotype PVL 5904, nearly complete skull. It was discovered and collected from the upper section of the Los Colorados Formation of the Ischigualasto-Villa Unión Basin.

Dipluridae

The family Dipluridae, known as curtain-web spiders (or confusingly with other distantly related ones as funnel-web tarantulas) are a group of spiders in the infraorder Mygalomorphae, that have two pairs of booklungs, and chelicerae (fangs) that move up and down in a stabbing motion. A number of genera, including that of the Sydney funnel-web spider (Atrax), used to be classified in this family but have now been moved to Hexathelidae.

Eudimorphodontidae

Eudimorphodontidae is an extinct family of early pterosaurs from the Late Triassic (early Norian to Rhaetian age) of Europe. It was named by Peter Wellnhofer in 1978 to include Eudimorphodon ranzii. Some phylogenetic analyses suggested that Eudimorphodontidae is a junior synonym of Campylognathoididae, however more comprehensive analyses found Eudimorphodontidae to be basal to Macronychoptera that includes Campylognathoididae and more derived pterosaurs (Breviquartossa). Wang et al. (2009) found Eudimorphodontidae to include six species (the monospecific Peteinosaurus, Raeticodactylus and Caviramus, and three species of Eudimorphodon), but they didn't defined the clade. Brian Andres (2010, in press) define Eudimorphodontidae and found Peteinosaurus to be most closely related to it. Furthermore, he found monophyletic Eudimorphodon clade (unlike Wang et al., 2009 and Dalla Vecchia, 2009), and defined two subfamilies within Eudimorphodontidae. The Eudimorphodontinae includes all taxa more closely related to Eudimorphodon ranzii than to Raeticodactylus filisurensis while the Raeticodactylinae includes all taxa more closely related to Raeticodactylus filisurensis than to Eudimorphodon ranzii. More recently, Raeticodactylus and Caviramus were moved into their own family, Raeticodactylidae. The below cladogram follows that analysis.

Fasolasuchus

Fasolasuchus is an extinct genus of rauisuchid. Fossils have been found in the Los Colorados Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina that date back to the Norian stage of the Late Triassic, making it one of the last rauisuchians to have existed before the order became extinct at the end of the Triassic.

Hemiprotosuchus

Hemiprotosuchus is an extinct genus of protosuchid from the Late Triassic (Norian stage) Los Colorados Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina, South America. It was named by prolific Argentinian paleontologist José Bonaparte in 1969. The type species is H. leali.

Isanosaurus

Isanosaurus (meaning "Isan [north-eastern Thailand] lizard") was one of the first sauropod dinosaurs. It lived approximately 210 million years ago during the Late Triassic (late Norian to Rhaetian stages) in Thailand. The only species is Isanosaurus attavipachi. Though important for the understanding of sauropod origin and early evolution, Isanosaurus is poorly known. Exact relationships to other early sauropods remain unresolved.

Jaklapallisaurus

Jaklapallisaurus is a genus of unaysaurid sauropodomorph dinosaur. It lived during the Late Triassic period (late Norian to earliest Rhaetian) in what is now Andhra Pradesh, central India. It is known from the holotype ISI R274, postcranial material which was collected from the Upper Maleri Formation (late Norian–earliest Rhaetian) of the Pranhita–Godavari Basin and from the referred material ISI R279, partially complete right femur which was collected from the Lower Dharmaram Formation (latest Norian–Rhaetian). It was first named by Fernando E. Novas, Martin D. Ezcurra, Sankar Chatterjee and Tharavat S. Kutty in 2011 and the type species is Jaklapallisaurus asymmetrica. The generic name is derived from the Indian town of Jaklapalli which is close to the type locality. The specific name refers to the highly asymmetrical astragalus of this species in distal view. A cladistic analysis by Novas et al. found that all valid plateosaurid species form a large polytomy. Jaklapallisaurus was found along with the basal sauropodomorph Nambalia, a guaibasaurid, and two basal dinosauriforms.

Late Triassic

The Late Triassic is the third and final of three epochs of the Triassic Period in the geologic timescale. The Triassic-Jurassic extinction event began during this epoch and is one of the five major mass extinction events of the Earth. The corresponding series is known as the Upper Triassic. In Europe the epoch was called the Keuper, after a German lithostratigraphic group (a sequence of rock strata) that has a roughly corresponding age. The Late Triassic spans the time between 237 Ma and 201.3 Ma (million years ago). The Late Triassic is divided into the Carnian, Norian and Rhaetian ages.

Many of the first dinosaurs evolved during the Late Triassic, including Plateosaurus, Coelophysis, and Eoraptor.

The extinction event that began during the Late Triassic resulted in the disappearance of about 76% of all terrestrial and marine life species, as well as almost 20% of taxonomic families. Although the Late Triassic Epoch did not prove to be as destructive as the preceding Permian Period, which took place approximately 50 million years earlier and destroyed about 70% of land species, 57% of insect families as well as 95% of marine life, it resulted in great decreased in population sizes of many living organism populations.

Specifically, the Late Triassic had negative effects on the conodonts and ammonoid groups. These groups once served as vital index fossils, which made it possible to identify feasible life span to multiple strata of the Triassic strata. These groups were severely affected during the epoch, and became extinct soon after. Despite the large populations that withered away with the coming of the Late Triassic, many families, such as the pterosaurs, crocodiles, mammals and fish were very minimally affected. However, such families as the bivalves, gastropods, marine reptiles and brachiopods were greatly affected and many species became extinct during this time.

Lessemsaurus

Lessemsaurus is an extinct genus of sauropod dinosaur belonging to Lessemsauridae.

Phytosaur

Phytosaurs are an extinct group of large, mostly semiaquatic Late Triassic archosauriform reptiles. Phytosaurs belong to the family Phytosauridae and the order Phytosauria. Phytosauria and Phytosauridae are often considered to be equivalent groupings containing the same species, but some studies have identified non-phytosaurid phytosaurians. Phytosaurs were long-snouted and heavily armoured, bearing a remarkable resemblance to modern crocodilians in size, appearance, and lifestyle, as an example of convergence or parallel evolution. The name "phytosaur" means "plant reptile", as the first fossils of phytosaurs were mistakenly thought to belong to plant eaters. The name is misleading because the sharp teeth in phytosaur jaws clearly show that they were predators.

For many years, phytosaurs were considered to be the most basal group of Pseudosuchia (crocodile-line archosaurs), meaning that they were thought to be more closely related to the crocodilians than to birds (the other living group of archosaurs). Some recent studies of the evolutionary relationships of early archosauriforms suggest that phytosaurs evolved before the split between crocodile- and bird-line archosaurs and are the sister taxon of Archosauria. Others retain the older classification of phytosaurs as pseudosuchians.

Phytosaurs had a nearly global distribution during the Triassic. Fossils have been recovered from Europe, North America, India, Morocco, Thailand, Brazil, Greenland and Madagascar. Fossils attributed to phytosaurs have been found in Early Jurassic rocks, possibly extending their temporal range beyond the Triassic-Jurassic boundary.

Plateosauridae

Plateosauridae is a family of plateosaurian sauropodomorphs from the Late Triassic of Europe. Although several dinosaurs have been classified as plateosaurids over the years, the family Plateosauridae is now restricted to Plateosaurus. In another study, Yates (2003) sunk Sellosaurus into Plateosaurus (as P. gracilis).

Powellvenator

Powellvenator is an extinct genus of coelophysoid theropod dinosaur that lived during the latter part of the Triassic Period in what is now northwestern Argentina. Fossils of the dinosaur were found in the Los Colorados Formation of the Ischigualasto-Villa Unión Basin. The type species, Powellvenator podocitus, was named by Martin Ezcurra in 2017.

Pseudhesperosuchus

Pseudhesperosuchus (meaning "false Hesperosuchus") is a genus of sphenosuchian, a type of basal crocodylomorph, the clade that comprises the crocodilians and their closest kin. It is known from a partial skeleton and skull found in rocks of the Late Triassic (Norian-age) Los Colorados Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina.

Rhynchosaur

Rhynchosaurs were a group of Triassic diapsid reptiles from the group Archosauromorpha, meaning they were distantly related to the archosaurs.

Riojasaurus

Riojasaurus (meaning "Rioja lizard") was a herbivorous sauropodomorph dinosaur named after La Rioja Province in Argentina where it was found in the Los Colorados Formation in the Ischigualasto-Villa Unión Basin by José Bonaparte. It lived during the Late Triassic (Norian stage) and grew to about 10 metres (33 ft) long. Riojasaurus is the only known riojasaurid to live in South America.

Testudinata

Testudinata is the group of all tetrapods with a true turtle shell. It includes both modern turtles (Testudines) and many of their extinct, shelled relatives (stem-turtles). Though it was first coined as the group containing turtles by Klein in 1760, it was first defined in the modern sense by Joyce and colleagues in 2004. Testudinata does not include the primitive stem-turtle Odontochelys, which only had the bottom half of a shell.

A recent phylogenetic tree of Testudinata included Angolachelonia and Testudines as sister-taxa and subgroups of Testudinata .

Trechnotheria

Trechnotheria is a group of mammals that includes the therians and some fossil mammals from the Mesozoic Era. In the Jurassic through Cretaceous periods, the group was endemic to what would be Asia and Africa.Trechnotheria has been assigned various ranks, but was originally called a "superlegion" by the original author.

One reference has defined the Trechnotheria as the clade comprising the last common ancestor of Zhangheotherium and living therian mammals, and all its descendants.

Cenozoic era
(present–66.0 Mya)
Mesozoic era
(66.0–251.902 Mya)
Paleozoic era
(251.902–541.0 Mya)
Proterozoic eon
(541.0 Mya–2.5 Gya)
Archean eon (2.5–4 Gya)
Hadean eon (4–4.6 Gya)

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