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The Hettangian
Hettangian
is the earliest age or lowest stage of the Jurassic period of the geologic timescale. It spans the time between 201.3 ± 0.2 Ma and 199.3 ± 0.3 Ma (million years ago).[2] The Hettangian follows the Rhaetian
Rhaetian
(part of the Triassic
Triassic
period) and is followed by the Sinemurian.[3] In European stratigraphy the Hettangian
Hettangian
is a part of the time span in which the Lias was deposited. An example is the British Blue Lias, which has an upper Rhaetian
Rhaetian
to Sinemurian
Sinemurian
age. Another example is the lower Lias from the Northern Limestone Alps
Northern Limestone Alps
where well-preserved but very rare ammonites, including Alsatites, have been found.

Contents

1 Stratigraphic definitions

1.1 Biostratigraphy

2 Palaeontology

2.1 †Ammonites 2.2 †Ichthyosaurs 2.3 Synapsids

2.3.1 Mammaliaformes

2.4 †Ornithischians 2.5 †Plesiosaurs

3 See also 4 References

4.1 Notes 4.2 Literature

5 External links

Stratigraphic definitions[edit] The Hettangian
Hettangian
was introduced in the literature by Swiss palaeontologist, Eugène Renevier, in 1864. The stage takes its name from Hettange-Grande, a town in north-eastern France, just south of the border with Luxembourg
Luxembourg
on the main road from Luxembourg
Luxembourg
City to Metz. The base of the Hettangian
Hettangian
stage (which is also the base of the Lower Jurassic
Jurassic
series and the entire Jurassic
Jurassic
system) is defined as the place in the stratigraphic column where fossils of the ammonite genus Psiloceras
Psiloceras
first appear. A global reference profile (a GSSP) for the base was defined 2010 at the Kuhjoch in the Karwendel
Karwendel
in western Austria.[4] The top of the Hettangian
Hettangian
stage (the base of the Sinemurian) is at the first appearances of ammonite genera Vermiceras and Metophioceras. Biostratigraphy[edit] The Hettangian
Hettangian
contains three ammonite biozones in the Tethys domain:

zone of Schlotheimia
Schlotheimia
angulata zone of Alsatites
Alsatites
liasicus zone of Psiloceras
Psiloceras
planorbis

Palaeontology[edit] †Ammonites[edit]

Alsatites
Alsatites
proaries

At the end of the Triassic
Triassic
period, the ammonites died out almost entirely. During the Hettangian, however, the "Neoammonites" developed relatively quickly, so that even in the middle Hettangian
Hettangian
a large number of genera and species existed. †Ichthyosaurs[edit]

Ichthyosauria
Ichthyosauria
of the Hettangian

Taxa Presence Location Description Images

Ichthyosaurus

From Hettangian
Hettangian
to Sinemurian Belgium, England, Germany Among the best known ichthyosaur genera, was smaller than most of its relatives, measuring 2 m (6 ft 7 in) in length.

Ichthyosaurus

Temnodontosaurus

Leptonectes

Europe

Temnodontosaurus

From Hettangian
Hettangian
to Toarcian England, Germany The first Ichthyosaur, T.platyodon discovered by Mary Anning from the Blue Lias
Blue Lias
at Lyme Regis. Species of Temnodontosaurus
Temnodontosaurus
were large, exceeding 12 meters (39 feet) in length.

Synapsids[edit]

Non-Mammaliaform Synapsids
Synapsids
of the Hettangian

Taxa Presence Location Description Images

Bienotherium

Lufeng Formation

Mammaliaformes[edit]

Mammaliaformes
Mammaliaformes
of the Hettangian

Taxa Presence Location Description Images

Haramiya

†Ornithischians[edit]

Ornithischians
Ornithischians
of the Hettangian

Taxa Presence Location Description Images

Abrictosaurus

From Hettangian
Hettangian
to Sinemurian Upper Elliot Formation, Lesotho and Cape Province, South Africa Considered the most basal member of the family Heterodontosauridae

Abrictosaurus

Heterodontosaurus

Scelidosaurus

Fabrosaurus

From Hettangian
Hettangian
to Sinemurian Lesotho As the only fossil known of it is a partial jawbone with three teeth, Fabrosaurus
Fabrosaurus
is a nomen dubium.

Heterodontosaurus

Upper Elliot Formation, Cape Province, South Africa A small, fleet-footed ornithischian that reached a maximum size of about 3 feet. The hand of Heterodontosaurus
Heterodontosaurus
had five fingers, two of which seem to be opposable, allowing Heterodontosaurus
Heterodontosaurus
to grasp and manipulate food. Another interesting feature is the specialization of teeth which gave rise to the animal's name. At the front of the jaw beside the beak were small teeth likely used for chopping off leaves and stems.

Lanasaurus

From Hettangian
Hettangian
to Sinemurian Upper Elliot Formation, Orange Free State, South Africa A heterodontosaurid ornithischian

Lycorhinus

From Hettangian
Hettangian
to Sinemurian Upper Elliot Formation, Cape Province, South Africa A small herbivore dinosaur despite long canines it sported in its jaws; due to this unique characteristic it is very clearly allied to Heterodontosaurus

Scelidosaurus

From Hettangian
Hettangian
to Sinemurian Charmouth, West Dorset, England; Kayenta Formation, Arizona, USA A genus of quadrupedal, lightly plated, herbivorous dinosaur about 4 meters (13 feet) long

Scutellosaurus

Arizona, USA A bipedal armored herbivore, was around 1.3 m (4 ft 3 in) long, 0.5 m (20 in) tall at the hips, and weighed 10 kg (22 lb).

Stormbergia

From Hettangian
Hettangian
to Sinemurian Stormberg Series Formations, South Africa, Lesotho A primitive ornithischian, about 2 meters long. The proportions of the posterior limbs show differences with those of Lesothosaurus, and reveal a lower ability to run

†Plesiosaurs[edit]

Plesiosauria
Plesiosauria
of the Hettangian

Taxa Presence Location Description Images

Atychodracon

Hettangian Barrow-upon-Soar, Leicestershire, England A genus of sauropterygian carnivorous reptile. It was about 7 m long.

Atychodracon

Macroplata

Macroplata

Hettangian Harbury, Warwickshire, UK

See also[edit]

Triassic- Jurassic
Jurassic
extinction event Komlosaurus carbonis

References[edit] Notes[edit]

^ http://www.stratigraphy.org/index.php/ics-chart-timescale ^ 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) ^ GSSP
GSSP
Table Archived 2012-11-15 at the Wayback Machine.

Literature[edit]

Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press. Renevier, E.: Notices géologiques et paléontologiques sur les Alpes Vaudoises, et les régions environnantes. I. Infralias et Zone à Avicula contorta (Étage Rhaetien) des Alpes Vaudoises Bulletin de la Société Vaudoise des Sciences Naturelles 8, p. 39-97. (in French)

External links[edit]

GeoWhen Database - Hettangian Lower Jurassic
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

v t e

Jurassic
Jurassic
Period

Lower/Early Jurassic Middle Jurassic Upper/Late Jurassic

Hettangian Sinemurian Pliensbachian Toarcian

Aalenian Bajocian Bathonian Callovian

Oxfordian Kimmeridgian Tithonian

v t e

Geologic history of Earth

Cenozoic
Cenozoic
era¹ (present–66.0 Mya)

Quaternary
Quaternary
(present–2.588 Mya)

Holocene
Holocene
(present–11.784 kya) Pleistocene
Pleistocene
(11.784 kya–2.588 Mya)

Neogene
Neogene
(2.588–23.03 Mya)

Pliocene
Pliocene
(2.588–5.333 Mya) Miocene
Miocene
(5.333–23.03 Mya)

Paleogene (23.03–66.0 Mya)

Oligocene
Oligocene
(23.03–33.9 Mya) Eocene
Eocene
(33.9–56.0 Mya) Paleocene
Paleocene
(56.0–66.0 Mya)

Mesozoic
Mesozoic
era¹ (66.0–251.902 Mya)

Cretaceous
Cretaceous
(66.0–145.0 Mya)

Late (66.0–100.5 Mya) Early (100.5–145.0 Mya)

Jurassic
Jurassic
(145.0–201.3 Mya)

Late (145.0–163.5 Mya) Middle (163.5–174.1 Mya) Early (174.1–201.3 Mya)

Triassic
Triassic
(201.3–251.902 Mya)

Late (201.3–237 Mya) Middle (237–247.2 Mya) Early (247.2–251.902 Mya)

Paleozoic
Paleozoic
era¹ (251.902–541.0 Mya)

Permian
Permian
(251.902–298.9 Mya)

Lopingian
Lopingian
(251.902–259.8 Mya) Guadalupian
Guadalupian
(259.8–272.3 Mya) Cisuralian
Cisuralian
(272.3–298.9 Mya)

Carboniferous
Carboniferous
(298.9–358.9 Mya)

Pennsylvanian (298.9–323.2 Mya) Mississippian (323.2–358.9 Mya)

Devonian
Devonian
(358.9–419.2 Mya)

Late (358.9–382.7 Mya) Middle (382.7–393.3 Mya) Early (393.3–419.2 Mya)

Silurian
Silurian
(419.2–443.8 Mya)

Pridoli (419.2–423.0 Mya) Ludlow (423.0–427.4 Mya) Wenlock (427.4–433.4 Mya) Llandovery (433.4–443.8 Mya)

Ordovician
Ordovician
(443.8–485.4 Mya)

Late (443.8–458.4 Mya) Middle (458.4–470.0 Mya) Early (470.0–485.4 Mya)

Cambrian
Cambrian
(485.4–541.0 Mya)

Furongian (485.4–497 Mya) Series 3 (497–509 Mya) Series 2 (509–521 Mya) Terreneuvian
Terreneuvian
(521–541.0 Mya)

Proterozoic
Proterozoic
eon² (541.0 Mya–2.5 Gya)

Neoproterozoic era (541.0 Mya–1 Gya)

Ediacaran
Ediacaran
(541.0-~635 Mya) Cryogenian (~635-~720 Mya) Tonian (~720 Mya-1 Gya)

Mesoproterozoic era (1–1.6 Gya)

Stenian (1-1.2 Gya) Ectasian (1.2-1.4 Gya) Calymmian (1.4-1.6 Gya)

Paleoproterozoic era (1.6–2.5 Gya)

Statherian (1.6-1.8 Gya) Orosirian
Orosirian
(1.8-2.05 Gya) Rhyacian (2.05-2.3 Gya) Siderian
Siderian
(2.3-2.5 Gya)

Archean
Archean
eon² (2.5–4 Gya)

Eras

Neoarchean (2.5–2.8 Gya) Mesoarchean (2.8–3.2 Gya) Paleoarchean
Paleoarchean
(3.2–3.6 Gya) Eoarchean
Eoarchean
(3.6–4 Gya)

Hadean
Hadean
eon² (4–4.6 Gya)

 

 

kya = thousands years ago. Mya = millions years ago. Gya = billions years ago.¹ = Phanerozoic
Phanerozoic
eon. ² = Precambrian
Precambrian
supereon. Source: (2017/02). International Commission on Stratigraphy. Retrieved 13 July 2015. Divisions of Geologic Time—Major Chronostratigraphic and Geochronologic Units USGS Retrie

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