Toarcian

Toarcian
	182.7 ± 0.7 – 174.1 ± 1.0 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Chronology
	Key events in the Jurassic -200 — – -195 — – -190 — – -185 — – -180 — – -175 — – -170 — – -165 — – -160 — – -155 — – -150 — – -145 — – M; e; s; o; z; o; i; c T J; u; r; a; s; s; i; c K L; T E; a; r; l; y M; i; d; d; l; e L; a; t; e E; K Rhaetian Hettangian Sinemurian Pliensbachian Toarcian Aalenian Bajocian Bathonian Callovian Oxfordian Kimmeridgian Tithonian Berriasian how to approximate the timescale of key Jurassic events.; Vertical axis: millions of years ago.;
Etymology
Name formality	Formal
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Age
Stratigraphic unit	Stage
Time span formality	Formal
Lower boundary definition	Peniche, Portugal
Lower boundary GSSP	FAD of the Ammonite D. (E.) simplex; 39.3708°N 9.3853°W
GSSP ratified	2014[1]
Upper boundary definition	FAD of the Ammonites Leioceras opalinum and Leioceras lineatum
Upper boundary GSSP	Fuentelsaz, Spain; 41.1708°N 1.8333°W
GSSP ratified	2000[2]

The Toarcian is, in the ICS' geologic timescale, an age and stage in the Early or Lower Jurassic. It spans the time between 182.7 Ma (million years ago) and 174.1 Ma.[3] It follows the Pliensbachian and is followed by the Aalenian.[4]

The Toarcian age began with the Toarcian turnover, the extinction event that sets its fossil faunas apart from the previous Pliensbachian age.

Stratigraphic definitions

The Toarcian takes its name from the city of Thouars, just south of Saumur in the Loire Valley of France. The stage was introduced by French palaeontologist Alcide d'Orbigny in 1842, after examining rock strata of this age in a quarry near Thouars.

In Europe this period is represented by the upper part of the Lias.

The base of the Toarcian is defined as the place in the stratigraphic record where the ammonite genus Eodactylites first appears. A global reference profile (a GSSP) for the base is located at Peniche, Portugal. The top of the stage is at the first appearance of ammonite genus Leioceras.

In the Tethys domain, the Toarcian contains the following ammonite biozones:

zone of Pleydellia aalensis
zone of Dumortieria pseudoradiosa
zone of Phlyseogrammoceras dispansum
zone of Grammoceras thouarcense
zone of Haugia variabilis
zone of Hildoceras bifrons
zone of Harpoceras serpentinum
zone of Dactylioceras tenuicostatum

Palaeontology

Amphibians

Amphibians of the Toarcian
Taxa	Presence	Location	Description	Images
Siderops	Pliensbachian-Toarcian	Evergreen Formation, Australia	A brachyopoid stereospondyl.	Siderops Notobatrachus
Notobatrachus N. reigi	Upper Toarcian	Cañadón Asfalto Formation, Chubut, Argentina	An extinct genus of archaeobatrachian frog and a member of the extant family Ascaphidae. One of the oldest true frogs discovered.

†Ichthyosaurs

Ichthyosaurs of the Toarcian
Taxa	Presence	Location	Description	Images
Stenopterygius		Europe
Temnodontosaurus	Hettangian to Toarcian	All over Europe	An ichthyosaur that exceeded 12 metres (39 ft) in length

†Ornithischians

Ornithischians of the Toarcian
Taxa	Presence	Location	Description	Images
Emausaurus		Ciechocinek Formation, Germany	Armored dinosaur known from a skull and partial postcranial remains, although only the skull is known well. Armor includes conical scutes and tall, spiny elements.

†Plesiosaurs

Plesiosauria of the Toarcian
Taxa	Presence	Location	Description	Images
Bishanopliosaurus		Ziliujing Formation, China	A pliosauroid, possibly a rhomaleosaurid.	Bishanopliosaurus Hydrorion Meyerasaurus Microcleidus Rhomaleosaurus Seeleysaurus
Hauffiosaurus		England and Germany	A basal pliosaurid.
Hydrorion		Posidonia Shale formation, Germany	A basal plesiosauroid.
Lusonectes		Portugal	A basal plesiosauroid, likely a close relative of Microcleidus.
Meyerasaurus		Holzmaden,southwestern Germany	A rhomaleosaurid. Its skull has a length of 37 cm, and the animal was about 3.35 m (11.0 ft) in length.
Microcleidus M. homalospondylus M. macropterus M. tournemirensis M. melusinae		Tournemire, Aveyron, France	A plesiosaur similar to Elasmosaurus, measuring around 3 meters in length. A fossil of a single but nearly complete skeleton of an animal approximately 4 meters (13 ft) long, originally described as Occitanosaurus tournemirensis, is now considered as a species of Microcleidus..
Plesiopterys		Posidonia Shale formation, Germany	A basal plesiosauroid, possibly a close relative of Cryptoclidus.
Rhomaleosaurus	Toarcian	Alum Shale, Yorkshire, England	A genus of sauropterygian carnivorous reptile belonging to the pliosaur superfamily, it was about 7m long.
Seeleyosaurus	Toarcian	Württemberg, Germany	A large (about 3 to 5 meters long), microcleidid, it was distinguished by its small head, long and slender neck, broad turtle like body, a short tail, and two pairs of large, elongated paddles
Sthenarosaurus		England	A genus of rhomaleosaurid pliosaur.

†Sauropods

Sauropoda of the Toarcian
Taxa	Presence	Location	Description	Images
Barapasaurus		Maharastra, India	Reached a length of about 18 metres (60 feet), and weighed about 48 tones (53 tons). Its height to the hip was approximately 5.5 metres (18 feet)	Barapasaurus
Rhoetosaurus	Disputed	Central Queensland, Australia	Estimated to have been about 12–15 metres long. Has been compared to Shunosaurus, based on similar general age, but without justification.
Tazoudasaurus	Toarcian	Ouarzazate province, Morocco	Small primitive sauropod, about 9 metres long. Member of Vulcanodontidae family.[5]

†Thalattosuchians

Thalattosuchia of the Toarcian
Taxa	Presence	Location	Description	Images
Macrospondylus	Early Toarcian	Whitby Mudstone Formation of England, and Germany	A machimosaurid teleosauroid.	Pelagosaurus Platysuchus Macrospondylus
Mystriosaurus	Early Toarcian	Whitby Mudstone Formation of England, and Germany	A teleosaurid teleosauroid.
Peipehsuchus		China	A basal metriorhynchoid.
Pelagosaurus	Early Toarcian	England, France, and Germany	A basal metriorhynchoid.
Platysuchus	Early Toarcian	Germany, and Luxembourg	A teleosaurid teleosauroid in the subfamily Teleosaurinae.
Plagiophthalmosuchus	Early Toarcian	Whitby Mudstone Formation of England, and Luxembourg	A basal teleosauroid.

Theropods

Theropods of the Aalenian
Taxa	Presence	Location	Description	Images
Asfaltovenator	Toarcian-Bajocian	Cañadón Asfalto Basin, Patagonia, Argentina	A large basal carnosaur. The unique combination of characteristics seen in Asfaltovenator may indicate megalosauroids and allosauroids shared a common ancestor not shared with Coelurosauria.	Berberosaurus. Condorraptor. Magnosaurus.
Berberosaurus	Middle Toarcian	Azilal Formation in the High Atlas of Toundoute, Ouarzazate, Morocco.	A primitive, medium sized neotheropod, possibly a dilophosaurid but most likely a basal ceratosaur.
Condorraptor	Aalenian-Bajocian	Cañadón Asfalto Basin, Patagonia, Argentina	It was among the earliest large South American theropods.
Magnosaurus	Aalenian-Bajocian	Dorset, England	Magnosaurus was one of the first megalosaurids to evolve.

References

da Rocha, Rogério Bordalo; Mattioli, Emanuela; Duarte, Luís Vítor; Pittet, Bernard; Elmi, Serge; Mouterde, René; Cabral, Maria Cristina; Comas-Rengifo, Maria José; Gómez, Juan José; Goy, António; Hesselbo, Stephen P.; Jenkyns, Hugh C.; Littler, Kate; Mailliot, Samuel; Veiga de Oliveira, Luiz Carlos; Osete, Maria Luisa; Nicola, Perilli; Pinto, Susana; Ruget, Christiane; Suan, Guillaume (September 2016). "Base of the Toarcian Stage of the Lower Jurassic defined by the Global Boundary Stratotype Section and Point (GSSP) at the Peniche section (Portugal)". Episodes. 39 (3): 460–481. doi:10.18814/epiiugs/2016/v39i3/99741. Retrieved 29 August 2020.
Cresta, S.; Goy, A.; Arias, C.; Barrón, E.; Bernad, J.; Canales, M.; García-Joral, F.; García-Romero, E; Gialanella, P.; Gómez, J.; González, J.; Herrero, C.; Martínez2, G.; Osete, M.; Perilli, N.; Villalaín, J. (September 2001). "The Global Boundary Stratotype Section and Point (GSSP) of the Toarcian-Aalenian Boundary (Lower-Middle Jurassic)" (PDF). Episodes. 24: 166–175. Retrieved 13 December 2020.
Benton, Michael J. (2012). Prehistoric Life. Edinburgh, Scotland: Dorling Kindersley. pp. 44–45. ISBN 978-0-7566-9910-9.
For a detailed geologic timescale see Gradstein et al. (2004)
Allain, Ronan; Najat Aquesbi; Jean Dejax; Christian Meyer; Michel Monbaron; Christian Montenat; Philippe Richir; Mohammed Rochdy; Dale Russell; Philippe Taquet (2004). "A basal sauropod dinosaur from the Early Jurassic of Morocco" (PDF). Comptes Rendus Palevol. 3 (3): 199–208. doi:10.1016/j.crpv.2004.03.001. ISSN 1631-0683.

Sources

Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
d´Orbigny, A.C.V.M.D.; 1842: Paléontologie française. 1. Terrains oolitiques ou jurassiques, Bertrand, Paris. (in French)

External links

GeoWhen Database - Toarcian
Lower Jurassic timescale, at the website of the subcommission for stratigraphic information of the ICS
Stratigraphic chart of the Lower Jurassic, at the website of Norges Network of offshore records of geology and stratigraphy

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[1] Rocha, Rogério Bordalo; Mattioli, Emanuela; Duarte, Luís Vítor; Pittet, Bernard; Elmi, Serge; Mouterde, René; Cabral, Maria Cristina; Comas-Rengifo, Maria José; Gómez, Juan José; Goy, António; Hesselbo, Stephen P.; Jenkyns, Hugh C.; Littler, Kate; Mailliot, Samuel; Veiga de Oliveira, Luiz Carlos; Osete, Maria Luisa; Nicola, Perilli; Pinto, Susana; Ruget, Christiane; Suan, Guillaume (September 2016). "Base of the Toarcian Stage of the Lower Jurassic defined by the Global Boundary Stratotype Section and Point (GSSP) at the Peniche section (Portugal)". Episodes. 39 (3): 460–481. doi:10.18814/epiiugs/2016/v39i3/99741. Retrieved 29 August 2020.

[2] Cresta, S.; Goy, A.; Arias, C.; Barrón, E.; Bernad, J.; Canales, M.; García-Joral, F.; García-Romero, E; Gialanella, P.; Gómez, J.; González, J.; Herrero, C.; Martínez2, G.; Osete, M.; Perilli, N.; Villalaín, J. (September 2001). "The Global Boundary Stratotype Section and Point (GSSP) of the Toarcian-Aalenian Boundary (Lower-Middle Jurassic)" (PDF). Episodes. 24: 166–175. Retrieved 13 December 2020.

[benton,_2012-3] Benton, Michael J. (2012). Prehistoric Life. Edinburgh, Scotland: Dorling Kindersley. pp. 44–45. ISBN 978-0-7566-9910-9.

[4] For a detailed geologic timescale see Gradstein et al. (2004)

[allain04-5] Allain, Ronan; Najat Aquesbi; Jean Dejax; Christian Meyer; Michel Monbaron; Christian Montenat; Philippe Richir; Mohammed Rochdy; Dale Russell; Philippe Taquet (2004). "A basal sauropod dinosaur from the Early Jurassic of Morocco" (PDF). Comptes Rendus Palevol. 3 (3): 199–208. doi:10.1016/j.crpv.2004.03.001. ISSN 1631-0683.