Aegirosaurus

Aegirosaurus Temporal range: Late Jurassic-Early Cretaceous, Tithonian–Valanginian PreЄ Є O S D C P T J K Pg N
Fossil
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	†Ichthyosauria
Family:	†Ophthalmosauridae
Subfamily:	†Platypterygiinae
Genus:	†Aegirosaurus Bardet & Fernandez, 2000
Species:	† A. leptospondylus
Binomial name
Aegirosaurus leptospondylus (Wagner, 1853 [originally Ichthyosaurus])

Aegirosaurus is an extinct genus of platypterygiine ophthalmosaurid ichthyosaur known from the Late Jurassic and Early Cretaceous of Europe.

Discovery and species

Originally described by Wagner (1853) as Ichthyosaurus 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'.^[1]

Within Ophthalmosauridae, Aegirosaurus was regarded to be most closely related to Ophthalmosaurus.^[2] However, many recent cladistic analyses found it to be more closely related to Sveltonectes (and probably to Undorosaurus). Aegirosaurus lineage was found to include Brachypterygius and Maiaspondylus too, and to nest within Platypterygiinae which is the sister taxon of Ophthalmosaurinae.^[3][4]

Stratigraphic range

Aegirosaurus is known from the lower Tithonian (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.^[5] This shows that most types of Late Jurassic ichthyosaurs crossed the Jurassic-Cretaceous boundary.

Palaeobiology

It was a small genus of ichthyosaur, with adults being less than two metres in length.^[1] Tooth morphology and wear pattern suggest that Aegirosaurus belonged to the "Pierce II/ Generalist" feeding guild.^[5]

References