Carnian

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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 2020.[1]

The Carnian (less commonly, Karnian) is the lowermost stage of the Upper Triassic series (or earliest age of the Late Triassic epoch). It lasted from 237 to 227 million years ago (Ma).[2] The Carnian is preceded by the Ladinian and is followed by the Norian. Its boundaries are not characterized by major extinctions or biotic turnovers, but a climatic event (known as the Carnian Pluvial Event) occurred during the Carnian and seems to be associated with important extinctions or biotic radiations.

Stratigraphic definitions[edit]

Alluvial plain red clays of the Travenanzes Formation, upper Carnian, the Dolomites, northern Italy
Brotheotrachyceras brotheus from the San Cassiano Formation, Val Badia, Dolomites, Southern Alps. This ammonoid is an index fossil for the lower Carnian

The Carnian was named in 1869 by Mojsisovics. It is unclear if it was named after the Carnic Alps or after the Austrian region of Carinthia (Kärnten in German)[3] or after the Carnia historical region in northwestern Italy.[citation needed] The name, however, was first used referring to a part of the Hallstatt Limestone cropping out in Austria.[3]

The base of the Carnian stage is defined as the place in the stratigraphic record where the ammonite species Daxatina canadensis first appears. The global reference profile for the base is located at the Stuores-Wiesen near Badia in the Val Badia in the region of South Tyrol, Italy.[4]

The top of the Carnian (the base of the Norian) is at the bases of the ammonite biozones of Klamathites macrolobatus or Stikinoceras kerri and the conodont biozones of Metapolygnathus communisti or Metapolygnathus primitius.

Subdivisions[edit]

There is no established, standard usage for the Carnian subdivisions, thus, while in some regional stratigraphies a two-substage subdivision is common:

  • Julian
  • Tuvalian

others prefer a three-substage organization of the stage as follows:

  • Cordevolian
  • Julian
  • Tuvalian

Biostratigraphy[edit]

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

Paleogeography and climate[edit]

The paleogeography of the Carnian was basically the same as for the rest of the Triassic. Most continents were merged into the supercontinent Pangaea, and there was a single global ocean, Panthalassa. The global ocean had a western branch at tropical latitudes called Paleo-Tethys. The sediments of Paleo-Tethys now crop out in southeastern Europe, in the Middle East, in the Himalayas, and up to the island of Timor.

The extreme land-sea distribution led to "mega-monsoons", i.e., an atmospheric monsoon regime more intense than the present one.

As for most of the Mesozoic, there were no ice caps. Climate was mostly arid in the tropics, but an episode of wet tropical climate is documented at least in the Paleo-Tethys. This putative climatic event is called the "Carnian Pluvial Event", its age being between latest early Carnian (Julian) and the beginning of late Carnian (Tuvalian).

Carnian life[edit]

In the marine realm, the Carnian saw the first abundant occurrences of calcareous nannoplankton, a morphological group including the coccolithophores.

Invertebrates[edit]

There are a few invertebrates which are typical and characteristic of the Carnian. Among molluscs, the ammonoid genus Trachyceras is exclusive to the lower Carnian (i.e., Julian of the two-substages subdivision, see above). The family Tropitidae and the genus Tropites appear at the base of the upper Carnian (Tuvalian). The bivalve genus Halobia, a bottom-dweller of deep sea environments, differentiated from Daonella at the beginning of this age. Scleractinian coral reefs, i.e., reefs with corals of the modern type, became relatively common for the first time in the Carnian.

Vertebrates[edit]

The earliest dinosaur Eoraptor originated during the Carnian, around 230 Ma. The oldest well documented dinosaurian assemblage, in the Ischigualasto Formation of Argentina, is most probably late Carnian in age.

In this stage the archosaurs became the dominant faunas in the world, evolving into groups such as the phytosaurs, rhynchosaurs, aetosaurs, and rauisuchians. The first dinosaurs (and the pterosaur Carniadactylus) also appeared in this stage, and though at the time they were small and insignificant, they diversified rapidly and would dominate the fauna for the rest of the Mesozoic. On the other hand, the therapsids, which included the ancestors of mammals, decreased in both size and diversity, and would remain relatively small until the extinction of the dinosaurs.

Conodonts were present in Triassic marine sediments. Paragondolella polygnathiformis appeared at the base of the Carnian stage, and is considered a characteristic species. A partial list of Carnian vertebrates is given below. Many Carnian vertebrates are found in Santa Maria Formation rocks of the Paleorrota geopark.

Chondrichthyans[edit]

Chondrichthyes of the Carnian
Taxa Presence Location Description Images
Triassic England, Germany, India An xenacanth elasmobranch

Actinopterygians[edit]

Actinopterygii of the Carnian
Taxa Presence Location Description Images
Triassic China, Slovenia, Italy A non-neopterygian
Late Triassic United States A redfieldiiform non-neopterygian
Late Triassic United States A teleosteomorph (modern ray-fin)
Late Triassic Switzerland A neopterygian
Middle Triassic to Late Triassic Austria A teleosteomorph (modern ray-fin)
Middle Triassic to Early Jurassic Italy A non-neopterygian
Triassic China, Italy A non-neopterygian
Late Triassic Germany A neopterygian
Middle Triassic to Late Triassic Austria, Italy The earliest gliding fish

Coelacanths[edit]

Actinistia of the Carnian
Taxa Presence Location Description Images
Late Triassic United States A mawsoniid coelacanth
Late Triassic to Jurassic United States A mawsoniid coelacanth
Middle Triassic Austria A coelacanth

Temnospondyls[edit]

Temnospondyls of the Carnian
Taxa Presence Location Description Images
Argana Basin, High Atlas, Morocco
  • Cyclotosaurus
    • Cyclotosaurus ebrachensis
    • Cyclotosaurus buechneri
    • Cyclotosaurus robustus
    • Cyclotosaurus intermedius
Australia
Argana Basin, High Atlas, Morocco
All across the US and India
Europe and North America
Northwestern Argentina

†Chroniosuchians[edit]

Chroniosuchia of the Carnian
Taxa Presence Location Description Images
Late Triassic Madygen Formation, Kyrgyzstan A stem tetrapod

†Procolophonomorphs[edit]

Procolophonomorpha of the Carnian
Taxa Presence Location Description Images
Late Triassic Scotland A genus of lizard-shaped parareptile


†Sauropterygia[edit]

†Pachypleurosaurs[edit]
Pachypleurosauria of the Carnian
Taxa Presence Location Description Images
Middle Triassic China A sauropterygian
†Pistosaurs[edit]
Pistosauria of the Carnian
Taxa Presence Location Description Images
Middle Triassic Italy A sauropterygian
Late Triassic China A sauropterygian
†Placodonts[edit]
Placodonts of the Carnian
Taxa Presence Location Description Images
Early Carnian
Late Triassic Spain
Late Triassic China
Tuvalian China

†Thalattosaurs[edit]

Thalattosauria of the Carnian
Taxa Presence Location Description Images
Middle Triassic to Late Triassic China
Nectosaurus (left) and Thalattosaurus (right)
Late Triassic China
Late Triassic Falang Formation, Guizhou, China A relatively large thalattosaurian, more than 4 metres (13 ft) long
Late Triassic United States
Middle Triassic to Late Triassic United States
Middle Triassic to Late Triassic China

†Ichthyosaurs[edit]

Ichthyosaurs of the Carnian
Taxa Presence Location Description Images
An elongate ichthyosaur
A large ichthyosaur
A large ichthyosaur

†Archosauromorphs and Archosauriformes (non-archosaurian)[edit]

Non-Archosaurian Archosauromorphs of the Carnian
Taxa Presence Location Description Images
Doswell Formation, Virginia Doswellia was a low and heavily built carnivore.
Middle Triassic to Late Triassic Chañares Formation, Argentina A genus of modest sized proterochampsid.
Middle Triassic to Late Triassic Chañares Formation, Argentina A genus of proterochampsid archosauriform.
  • Hyperodapedon gordoni
  • Hyperodapedon huxleyi
  • Hyperodapedon tikiensis
  • Hyperodapedon huenei
  • Hyperodapedon mariensis
  • Hyperodapedon sanjuanensis

Europe:

  • H. gordoni

India:

  • H. huxleyi
  • H. tikiensis

South America:

  • H. huenei
  • H. mariensis
  • H. sanjuanensis
One of the most derived genera of rhynchosaurs and the most widespread and diverse with at least six verified species from Europe, Asia and South America and potentially more species from Africa and North America.
Makay Formation, Madagascar A derived rhynchosaur and a very close relative of Hyperodapedon, possibly a species in that genus.
late Carnian Lower Dockum Group, Texas A genus of dubious hyperodapedontind rhynchosaurs.
Middle Triassic to Late Triassic Madygen Formation, Kyrgyzstan Archosauromorph with elongate integumentary appendages
late Carnian Krasiejów quarry, Poland A genus of gliding reptile closely related to Sharovipteryx. A recent phylogenetic analysis incorporating Ozimek found it as a member of the Tanystropheidae, as a close relative of Langobardisaurus and Tanytrachelos. This may suggest that both Ozimek and Sharovipteryx are members of the clade.
Santa Maria Formation, Argentina A genus of proterochampsid.
229 Ma Ischigualasto Formation, Argentina A genus of proterochampsid originally thought as a species of Chanaresuchus.
Calcare del Predil Formation, Italy A tanystropheid.
late Carnian — earliest Norian Santa Maria Formation, Argentina A genus of proterochampsid.
A tanystropheid.
Solite Quarry. Cascade, Virginia A tanystropheid.
A herbivorous lizard-like allokotosaur that reached up to 2.5 m long.
Middle Triassic to Late Triassic Chañares Formation, Argentina A genus of proterochampsid archosauriform.
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.
Archosaurs[edit]
†Pseudosuchians (non-crocodylomorphan, non-aetosaurian)[edit]
Non-crocodylomorph, non-aetosaurian Crurotarsans of the Carnian
Taxa Presence Location Description Images
†Aetosaurs[edit]
Aetosaurs of the Carnian
Taxa Presence Location Description Images
Crocodylomorphs[edit]
Crocodylomorphs of the Carnian
Taxa Presence Location Description Images
Late Carnian or early Norian
Avemetatarsalians[edit]
Dinosauromorphs of the Carnian
Taxa Presence Location Description Images
Maleri Formation, Andhra Pradesh, India A basal saurischian dinosaur
Disputed: considered Norian by some researchers Lesotho A sauropodomorph dinosaur.
Tecovas Formation, Texas possibly a synonym of Chindesaurus
Colorado City Formation, Texas, USA A herrerasaurid dinosaur
Carnian - Norian Timezgadiouine Formation, Argana Basin, Morocco A silesaurid dinosauriform
Ischigualasto-Villa Unión Basin, Argentine Northwest, Argentina One of the earliest dinosaurs. Possibly the most basal theropod.
Ischigualasto Formation, Argentina One of the earliest dinosaurs. Uncertain affinities.
Disputed: considered Norian by some researchers Lesotho, South Africa, Zimbabwe A large robust sauropodomorph, potentially up to 10 meters long.
Santa Maria Formation, Rio Grande do Sul, Brazil A herrerasaurid dinosaur.
Paleorrota, Brazil An early dinosaur of uncertain affinities, possibly a close relative of Saturnalia.
Argentina A large herrerasaurid dinosaur.
Ischigualasto Formation, Argentina A silesaurid dinosauriform.
Santa Maria Formation, Rio Grande do Sul, Brazil A lagerpetid dinosauromorph.
Ladinian - Carnian Chañares Formation, La Rioja Province, Argentina A lagerpetid dinosauromorph.
Ladinian - Carnian Chañares Formation, La Rioja Province, Argentina A basal dinosauromorph.
Ladinian - Carnian Chañares Formation, La Rioja Province, Argentina A basal dinosauriform.
Santa Maria Formation, Rio Grande do Sul, Brazil Basal saurischian dinosaur of uncertain affinities.
Early Carnian Ischigualasto Formation, San Juan, Argentina A very basal dinosaur, possibly the most basal sauropodomorph.
Ischigualasto Formation, San Juan, Argentina A small, lightly built herbivore approximately 1 metre (39 in) in length and 30 centimetres (12 in) in height. Considered to be either the oldest known ornithischian, or a silesaurid
Carnian - Norian Lossiemouth Sandstone Formation, Scotland A small dinosauriform.
Paleorrota, Rio Grande do Sul, Brazil May have been a primitive sauropodomorph, probably grew to about 1.5 metres (4.9 ft) long
Agudo, Rio Grande do Sul, Brazil A silesaurid dinosauriform.
Ischigualasto Formation, San Juan, Argentina A herrerasaurid dinosaur.
Lossiemouth Sandstone, Scotland Likely a basal avemetatarsalian. It's taxonomic status is heavily disputed.
Silesia, Poland A silesaurid dinosauriform, measuring over 2 meters long.
Middle Carnian Paleorrota, Rio Grande do Sul, Brazil One of the first dinosaurs from the Carnian to be discovered. A herrerasaurid.
Possible synonym of Staurikosaurus.

Lepidosaurs[edit]

Lepidosauria of the Carnian
Taxa Presence Location Description Images
Late Triassic Scotland a rhynchocephalian

†Therapsids (non-mammalian)[edit]

Non-mammalian Therapsids of the Carnian
Taxa Presence Location Description Images
Ischigualasto Formation, Argentnia
Paleorrota, Brazil
Chinle Formation, Arizona
Mammalia[edit]
Mammalia of the Carnian
Taxa Presence Location Discussion Images
Tecovas Formation, Palo Duro Canyon, Texas, USA Some writers consider Adelobasileus to be a mammal,[5] while those who limit Mammalia to the crown group do not include this genus. In any case, Adelobasileus is thought to be either the common ancestor of all modern mammals or else a close relative of that ancestor.

Classic localities and Lagerstätten[edit]

The lower Carnian fauna of the San Cassiano Formation (Dolomites, northern Italy) has been studied since the 19th century. Fossiliferous localities are many, and are distributed mostly in the surroundings of Cortina d'Ampezzo and in the high Badia Valley, near the village of San Cassiano, after which the formation was named. This fauna is extremely diverse, including ammonoids, gastropods, bivalves, echinoderms, calcareous sponge, corals, brachiopods, and a variety of less common fossils. A collection of this fauna is exposed in the "Museo delle Regole", a museum in Cortina d'Ampezzo.

The Ischigualasto Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina yielded a very important vertebrate association, including the oldest dinosaurian assemblage.

The Lagerstätte of the Madygen Formation in Kyrgysztan has provided over 20,000 fossil insects, vertebrates and flora.

References[edit]

  1. ^ "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. 2020.
  2. ^ http://www.stratigraphy.org/index.php/ics-chart-timescale
  3. ^ a b Gradstein, F.M.; Ogg, J.G.; Schmitz, M.D.; Ogg, G.M. (editors) (2012). The Geologic Timescale 2012 (volume 1). Elsevier. p. 687. ISBN 978-0-44-459390-0.CS1 maint: multiple names: authors list (link) CS1 maint: extra text: authors list (link)
  4. ^ The GSSP was firstly proposed by Broglio Loriga et al. (1999) and established by Mietto et al. (2012)
  5. ^ Lucas and Luo (1993).

Bibliography[edit]

  • 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.
  • Broglio Loriga, C.; Cirilli, S.; De Zanche, V.; Di Bari, D.; Gianolla, P.; Laghi, G.; Manfrin, S.; Mastandrea, A.; Mietto, P.; Muttoni, G.; Neri, C.; Posenato, R.; Rechichi, M.C.; Rettori R. & Roghi, G.; 1999: The Prati di Stuores/Stuores Wiesen section (Dolomites, Italy): a candidate Global Stratotype section and Point for the base of the Carnian stage, Rivista Italiana di Paleontologia e Stratigrafia 105, pp. 37–78.
  • Furin, S.; Preto, N.; Rigo, M.; Roghi, G.; Gianolla, P.; Crowley, J.L. & Bowring, S.A.; 2006: High-precision U-Pb zircon age from the Triassic of Italy: Implications for the Triassic time scale and the Carnian origin of calcareous nannoplankton and dinosaurs, Geology 34, p. 1009–1012.
  • Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
  • Gradstein, F.M.; Ogg, J.G., Schmitz, M.D. & Ogg, G.M.; 2012: The Geologic Time Scale 2012, Elsevier.
  • Lucas, S.G.; Luo, Zhe-Xi; 1993: Adelobasileus from the upper Triassic of west Texas: the oldest mammal, J. Vert. Paleont. 13, pp. 309–334.
  • Mietto, P.; Manfrin, S.; Preto, N.; Rigo, M.; Roghi, G.; Furin, S.; Gianolla, P.; Posenato, R.; Muttoni, G.; Nicora, A.; Buratti, N.; Cirilli, S.; Spoetl, C.; Ramezani, J. & Bowring, S.A.; 2012: The Global Boundary Stratotype Section and Point (GSSP) of the Carnian stage (Late Triassic) at Prati di Stuores/Stuores Wiesen section (Southern Alps, NE Italy), Episodes 35, pp. 414–430.

External links[edit]