The
Hettangian is the earliest age or lowest stage of the
JurassicThe Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
period of the geologic timescale. It spans the time between 199.6 ± 0.6 Ma and 196.5 ± 1 Ma (million years ago). The Hettangian follows the
RhaetianThe Rhaetian is in geochronology the latest age of the Triassic period or in chronostratigraphy the uppermost stage of the Triassic system. It lasted from 203.6 ± 1.5 to 199.6 ± 0.6 million years ago...
(part of the
TriassicThe Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
period) and is followed by the
SinemurianIn the geologic timescale, the Sinemurian is an age or stage in the Early or Lower Jurassic epoch or series. It spans the time between 196.5 ± 2 Ma and 189.6 ± 1.5 Ma...
.
In Europe stratigraphy the Hettangian is a part of the time span in which the
LiasLias may refer to:*In geology:**The Lias Group, a group in the stratigraphy of Great Britain, formed during the Late Triassic to Early Jurassic epochs. It includes the Blue Lias and White Lias...
was deposited. An example is the British
Blue LiasThe Blue Lias is a geologic formation in southern, eastern and western England and parts of South Wales, part of the Lias Group. The Blue Lias consists of a sequence of limestone and shale layers, laid down in latest Triassic and early Jurassic times, between 195 and 200 million years ago...
, which has an upper Rhaetian to Sinemurian age.
Stratigraphic definitions
The Hettangian was introduced in the literature by Swiss palaeontologist,
Eugène RenevierEugène Renevier Swiss geologist, was born at Lausanne, Switzerland, as a descendant of a noble family.In 1857 he became professor of geology and paleontology in the University of Lausanne...
, in 1864. The stage takes its name from
Hettange-GrandeHettange-Grande is a commune in the Moselle department in Lorraine in north-eastern France.-Geography:Hettange-Grande is located close to the borders between France, Germany, and Luxembourg.-History:...
, a town in northern
FranceThe French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, just south of the border with
LuxembourgLuxembourg , officially the Grand Duchy of Luxembourg , is a landlocked country in western Europe, bordered by Belgium, France, and Germany. It has two principal regions: the Oesling in the North as part of the Ardennes massif, and the Gutland in the south...
on the main road from Luxembourg City to
MetzMetz is a city in the northeast of France located at the confluence of the Moselle and the Seille rivers.Metz is the capital of the Lorraine region and prefecture of the Moselle department. Located near the tripoint along the junction of France, Germany, and Luxembourg, Metz forms a central place...
.
The base of the Hettangian stage (which is also the base of the Lower Jurassic
seriesSeries are subdivisions of rock layers made based on the age of the rock and corresponding to the dating system unit called an epoch, both being formally defined international conventions of the geological timescale. A series is therefore a sequence of rock depositions defining a...
and the entire Jurassic system) is defined as the place in the stratigraphic column where fossils of the
ammoniteAmmonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct subclass within the Molluscan class Cephalopoda which are more closely related to living coleoids Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct...
genusIn biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
PsilocerasPsiloceras is an extinct genus of cephalopod belonging to the ammonite subclass. Psiloceras fossils are commonly found at Lyme Regis, Dorset Coast, England. Here smooth-shelled Psiloceras planorbis are to be found as usually flattened fossils in the Blue Lias....
first appear. A global reference profile (a GSSP) for the base had in 2009 not yet been appointed, but a section at Kuhjoch in western
AustriaAustria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...
has been proposed. The top of the Hettangian stage (the base of the Sinemurian) is at the first appearances of ammonite
generaIn biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Vermiceras and
Metophioceras.
Biostratigraphy
The Hettangian contains three ammonite
biozoneBiostratigraphic units or Biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa....
s in the
Tethys domainThe Tethys Ocean was an ocean that existed between the continents of Gondwana and Laurasia during the Mesozoic era before the opening of the Indian Ocean.-Modern theory:...
:
- zone of Schlotheimia angulata
- zone of Alsatites liasicus
Alsatites is an extinct genus of cephalopod belonging to the Ammonite subclass....
- zone of Psiloceras planorbis
Psiloceras is an extinct genus of cephalopod belonging to the ammonite subclass. Psiloceras fossils are commonly found at Lyme Regis, Dorset Coast, England. Here smooth-shelled Psiloceras planorbis are to be found as usually flattened fossils in the Blue Lias....
†Ichthyosaurs
| Ichthyosauria of the Hettangian |
| Taxa |
Presence |
Location |
Description |
Images |
- Ichthyosaurus
Ichthyosaurus is an extinct genus of ichthyosaur from the Early Jurassic of Europe . It is among the best known ichthyosaur genera, with the Order Ichthyosauria being named after it...
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From Hettangian to SinemurianIn the geologic timescale, the Sinemurian is an age or stage in the Early or Lower Jurassic epoch or series. It spans the time between 196.5 ± 2 Ma and 189.6 ± 1.5 Ma...
|
Belgium, England, Germany |
Among the best known ichthyosaur genera, was smaller than most of its relatives, measuring 2 m (6 ft 6 inches) in length. |
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Mammaliaformes
MammaliaformesMammaliaformes is a clade that contains the mammals and their closest extinct relatives. Phylogenetically, it is defined as a clade including the most recent common ancestor of Sinoconodon, morganuconodonts, docodonts, Monotremata, Marsupialia, Placentalia, extinct members of this clade, and all...
of the Hettangian |
| Taxa |
Presence |
Location |
Description |
Images |
- Haramiya
Haramiya is a mammaliform that is a lineage either unrelated or a paraphyletic parent to multituberculates from the Mesozoic era.Only Haramiyas teeth and skull have been found; judging from these it has been constructed as a 12 cm creature with a resemblance to modern voles...
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†Ornithischians
| Ornithischians of the Hettangian |
| Taxa |
Presence |
Location |
Description |
Images |
- Abrictosaurus
Abrictosaurus is a genus of heterodontosaurid dinosaur from the Early Jurassic Period of what is now southern Africa. It was a small bipedal herbivore or omnivore, approximately 1.2 meters long, and weighing less than 45 kilograms .This dinosaur is known from the fossil remains of only...
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From Hettangian to SinemurianIn the geologic timescale, the Sinemurian is an age or stage in the Early or Lower Jurassic epoch or series. It spans the time between 196.5 ± 2 Ma and 189.6 ± 1.5 Ma...
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Upper Elliot Formation The Upper Elliot Formation is a geological formation dating to roughly between 200 to 190 million years ago and covering the Hettangian to Sinemurian stages. The Upper Elliot Formation is found in South Africa and Lesotho and is a member of the Stormberg Group. It consists mainly of limestone,...
, Lesotho and Cape Province, South Africa |
Considered the most basal member of the family Heterodontosauridae |
|
- Fabrosaurus
Fabrosaurus ) was a genus of herbivorous dinosaur which lived during the Early Jurassic . As the only fossil known of it is a partial jawbone with three teeth, Fabrosaurus is a nomen dubium and may in fact be the same as Lesothosaurus.Fabrosaurus was around 1 meter long...
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From Hettangian to SinemurianIn the geologic timescale, the Sinemurian is an age or stage in the Early or Lower Jurassic epoch or series. It spans the time between 196.5 ± 2 Ma and 189.6 ± 1.5 Ma...
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Lesotho |
As the only fossil known of it is a partial jawbone with three teeth, Fabrosaurus is a nomen dubium and may in fact be the same as Lesothosaurus Lesothosaurus is an herbivorous ornithischian dinosaur. It was named by paleontologist Peter Galton in 1978, the name meaning "lizard from Lesotho". The genus is monotypic, having only one valid species, Lesothosaurus diagnosticus, within the genus....
. |
HeterodontosaurusHeterodontosaurus is a genus of small herbivorous dinosaur with prominent canine teeth which lived in the Early Jurassic of South Africa. It was similar to a hypsilophodont in shape, and ate plants, despite its canines.Heterodontosaurus is currently known from specimens of the SAFM from South...
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Upper Elliot Formation The Upper Elliot Formation is a geological formation dating to roughly between 200 to 190 million years ago and covering the Hettangian to Sinemurian stages. The Upper Elliot Formation is found in South Africa and Lesotho and is a member of the Stormberg Group. It consists mainly of limestone,...
, Cape Province, South Africa |
A small, fleet-footed ornithischian that reached a maximum size of about 3 feet. The hand of Heterodontosaurus had five fingers, two of which seem to be opposable, allowing 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. |
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From Hettangian to SinemurianIn the geologic timescale, the Sinemurian is an age or stage in the Early or Lower Jurassic epoch or series. It spans the time between 196.5 ± 2 Ma and 189.6 ± 1.5 Ma...
|
Upper Elliot Formation The Upper Elliot Formation is a geological formation dating to roughly between 200 to 190 million years ago and covering the Hettangian to Sinemurian stages. The Upper Elliot Formation is found in South Africa and Lesotho and is a member of the Stormberg Group. It consists mainly of limestone,...
, Orange Free State, South Africa |
A heterodontosaurid ornithischian |
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Lycorhinus Lycorhinus is a genus of heterodontosaurid ornithischian dinosaur hailing from the Early Jurassic strata of the Elliot Formation located in the Cape Province, South Africa....
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From Hettangian to SinemurianIn the geologic timescale, the Sinemurian is an age or stage in the Early or Lower Jurassic epoch or series. It spans the time between 196.5 ± 2 Ma and 189.6 ± 1.5 Ma...
|
Upper Elliot Formation The Upper Elliot Formation is a geological formation dating to roughly between 200 to 190 million years ago and covering the Hettangian to Sinemurian stages. The Upper Elliot Formation is found in South Africa and Lesotho and is a member of the Stormberg Group. It consists mainly of limestone,...
, 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 |
ScelidosaurusScelidosaurus is a genus of quadrupedal, lightly plated, herbivorous dinosaur about long. It lived during the Early Jurassic Period, during the Hettangian to Sinemurian stages around 199.6 to 194 million years ago. Its fossils have been found in both England and in Arizona, in the United...
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From Hettangian to SinemurianIn the geologic timescale, the Sinemurian is an age or stage in the Early or Lower Jurassic epoch or series. It spans the time between 196.5 ± 2 Ma and 189.6 ± 1.5 Ma...
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Charmouth Charmouth is a village at the mouth of the River Char in West Dorset, England, with a population of 1,687 according to the 2001 census.-The village:...
, West Dorset, England; Kayenta FormationThe Kayenta Formation is a geologic layer in the Glen Canyon Group that is spread across the Colorado Plateau province of the United States, including northern Arizona, northwest Colorado, Nevada, and Utah. This rock formation is particularly prominent in southeastern Utah, where it is seen in the...
, Arizona, USA |
A genus of quadrupedal, lightly plated, herbivorous dinosaur about 4 meters long (13 ft) |
ScutellosaurusScutellosaurus is a genus of herbivorous dinosaur that lived in North America around 200 to 196 million years ago, in the Early Jurassic times....
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Arizona, USA |
A bipedal armored herbivore, was around 1.3 m (4 ft 4 inches) long, 0.5 m (18 in) tall at the hips, and weighed 10 kg (22 lb). |
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Stormbergia Stormbergia is a genus of early ornithischian dinosaur known from the upper Elliot Formation of South Africa and Lesotho, named by Richard Butler in 2005...
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From Hettangian to SinemurianIn the geologic timescale, the Sinemurian is an age or stage in the Early or Lower Jurassic epoch or series. It spans the time between 196.5 ± 2 Ma and 189.6 ± 1.5 Ma...
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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 Lesothosaurus is an herbivorous ornithischian dinosaur. It was named by paleontologist Peter Galton in 1978, the name meaning "lizard from Lesotho". The genus is monotypic, having only one valid species, Lesothosaurus diagnosticus, within the genus....
, and reveal a lower ability to run |
†Plesiosaurs
PlesiosauriaPlesiosauria is an order of Mesozoic marine reptiles. Plesiosaurs first appeared in the Early Jurassic Period and became especially common during the Jurassic Period, thriving until the K-T extinction at the end of the Cretaceous Period.The name "plesiosaur" is used to refer to the order...
of the Hettangian |
| Taxa |
Presence |
Location |
Description |
Images |
- Macroplata
Macroplata , meaning, , is an extinct genus of Early Jurassic basal plesiosaur which grew up to in length. Like other plesiosaurs, Macroplata probably lived on a diet of fish, using its sharp needle-like teeth to catch prey. Its shoulder bones were fairly large, indicating a powerful forward...
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Hettangian to ToarcianThe Toarcian is, in the ICS' geologic timescale, an age or stage in the Early or Lower Jurassic. It spans the time between 183.0 Ma and 175.6 Ma...
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HarburyHarbury is a village and civil parish in the Stratford-on-Avon district of Warwickshire, England. In the 2001 census it had a population of 2,485....
, Warwickshire, UK |
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RhomaleosaurusRhomaleosaurus is an extinct genus of Early Jurassic rhomaleosaurid pliosauroid known from Northamptonshire and from Yorkshire of the United Kingdom. It was first named by Harry Seeley in 1874 and the type species is Rhomaleosaurus cramptoni...
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Hettangian and ToarcianThe Toarcian is, in the ICS' geologic timescale, an age or stage in the Early or Lower Jurassic. It spans the time between 183.0 Ma and 175.6 Ma...
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Barrow-upon-Soar, Leicestershire, England |
A genus of sauropterygian carnivorous reptile belonging to the pliosaur superfamily, it was about 7m long. |
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Literature
;
2004:
A Geologic Time Scale 2004,
Cambridge University PressCambridge University Press is the publishing business of the University of Cambridge. Granted letters patent by Henry VIII in 1534, it is the world's oldest publishing house, and the second largest university press in the world...
.:
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.
External links