Aegirosaurus
Encyclopedia
Aegirosaurus is an extinct genus
of ophthalmosaurid ichthyosaur
known from the Late Jurassic
and Early Cretaceous
of Europe.
leptospondylus, it has had an unstable taxonomic history. It has also been named Ichthyosaurus trigonus posthumus, and identified with Macropterygius and Brachypterygius
extremus. In 2000, Bardet and Fernández found that the holotype specimen of Macropterygius is undiagnosible, thus this genus is a nomen dubium
. They selected a complete skeleton in a private collection as the neotype for this species, as the only other described specimen was destroyed in World War II
. A second specimen from the Munich collection was referred to the same taxon. Bardet and Fernández concluded that the neotype should be assigned to a new genus, Aegirosaurus. The name means 'Aegir (teutonic god of the ocean) lizard with slender vertebrae'.
Within Ophthalmosauridae
, Aegirosaurus is most closely related to Ophthalmosaurus
.
(Upper Jurassic) of Bavaria
, Germany
. Its remains were discovered in the Solnhofen limestone
formations, the same formations that have yielded numerous well-known fossils, such as Archaeopteryx
, Compsognathus
and Pterodactylus
.
In addition to its late Jurassic occurrence, Aegirosaurus has recently been discovered from the late Valanginian
(Early Cretaceous) of Southeastern France (Laux-Montaux
, department of Drôme
; Vocontian Basin), the first diagnostic ichthyosaur recorded from the Valanginian. This shows that most types of Late Jurassic ichthyosaurs crossed the Jurassic-Cretaceous boundary.
Genus
In 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...
of ophthalmosaurid ichthyosaur
Ichthyosaur
Ichthyosaurs were giant marine reptiles that resembled fish and dolphins...
known from the Late Jurassic
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.2 ± 4.0 to 145.5 ± 4.0 million years ago , which is preserved in Upper Jurassic strata. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age...
and Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
of Europe.
Discovery and species
Originally described by Wagner (1853) as IchthyosaurusIchthyosaurus
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...
leptospondylus, it has had an unstable taxonomic history. It has also been named Ichthyosaurus trigonus posthumus, and identified with Macropterygius and Brachypterygius
Brachypterygius
Brachypterygius is a genus of ophthalmosaurid ichthyosaur known from England and European Russia. Brachypterygius was named by Friedrich von Huene in 1922 and the type species is therefore Brachypterygius extremus. The holotype of B. extremus is known from Kimmeridgian stage of the Late Jurassic of...
extremus. In 2000, Bardet and Fernández found that the holotype specimen of Macropterygius is undiagnosible, thus this genus is a nomen dubium
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
. They selected a complete skeleton in a private collection as the neotype for this species, as the only other described specimen was destroyed in World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. A second specimen from the Munich collection was referred to the same taxon. Bardet and Fernández concluded that the neotype should be assigned to a new genus, Aegirosaurus. The name means 'Aegir (teutonic god of the ocean) lizard with slender vertebrae'.
Within Ophthalmosauridae
Ophthalmosauridae
Ophthalmosauridae is an extinct family of thunnosaur ichthyosaurs from the Middle Jurassic to the early Late Cretaceous of Asia, Australia, Europe, North America and South America. Currently, the oldest known ophthalmosaurid is Mollesaurus from the early Bajocian of Argentina. Named by George H...
, Aegirosaurus is most closely related to Ophthalmosaurus
Ophthalmosaurus
Ophthalmosaurus is an ichthyosaur of the Middle to Late Jurassic period , named for its extremely large eyes. It had a graceful 6 metre long dolphin-shaped body, and its almost toothless jaw was well adapted for catching squid...
.
Stratigraphic range
Aegirosaurus is known from the lower TithonianTithonian
In the geologic timescale the Tithonian is the latest age of the Late Jurassic epoch or the uppermost stage of the Upper Jurassic series. It spans the time between 150.8 ± 4 Ma and 145.5 ± 4 Ma...
(Upper Jurassic) of Bavaria
Bavaria
Bavaria, formally the Free State of Bavaria is a state of Germany, located in the southeast of Germany. With an area of , it is the largest state by area, forming almost 20% of the total land area of Germany...
, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
. Its remains were discovered in the Solnhofen limestone
Solnhofen limestone
The Solnhofen Plattenkalk is a Jurassic Konservat-Lagerstätte that preserves a rare assemblage of fossilized organisms, including highly detailed imprints of soft bodied organisms such as sea jellies...
formations, the same formations that have yielded numerous well-known fossils, such as Archaeopteryx
Archaeopteryx
Archaeopteryx , sometimes referred to by its German name Urvogel , is a genus of theropod dinosaur that is closely related to birds. The name derives from the Ancient Greek meaning "ancient", and , meaning "feather" or "wing"...
, Compsognathus
Compsognathus
Compsognathus was a small, bipedal, carnivorous theropod dinosaur. The animal was the size of a turkey and lived around 150 million years ago, the early Tithonian stage of the late Jurassic Period, in what is now Europe. Paleontologists have found two well-preserved fossils, one in Germany...
and Pterodactylus
Pterodactylus
Pterodactylus is a genus of pterosaurs, whose members are popularly known as pterodactyls. It was the first to be named and identified as a flying reptile...
.
In addition to its late Jurassic occurrence, Aegirosaurus has recently been discovered from the late Valanginian
Valanginian
In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 140.2 ± 3.0 Ma and 136.4 ± 2.0 Ma...
(Early Cretaceous) of Southeastern France (Laux-Montaux
Chauvac-Laux-Montaux
Chauvac-Laux-Montaux is a commune in the Drôme department in southeastern France.The commune comprises two villages, Chauvac and Le Laux, situated at the foot of the Col de Reychasset.-Population:-References:*...
, department of Drôme
Drôme
Drôme , a department in southeastern France, takes its name from the Drôme River.-History:The French National Constituent Assembly set up Drôme as one of the original 83 departments of France on March 4, 1790, during the French Revolution...
; Vocontian Basin), the first diagnostic ichthyosaur recorded from the Valanginian. This shows that most types of Late Jurassic ichthyosaurs crossed the Jurassic-Cretaceous boundary.