Neustosaurus
Encyclopedia
Neustosaurus is a genus
of marine crocodyliform from the Early Cretaceous
. Neustosaurus was a carnivore
that spent much, if not all, its life out at sea. No Neustosaurus eggs or nest have been discovered, so little is known of the reptile's lifecycle, unlike other large marine reptiles of the Mesozoic
, such as plesiosaur
s or ichthyosaurs which are known to give birth to live young out at sea. Where Neustosaurus mated, whether on land or at sea, is currently unknown. The name Neustosaurus means "Swimming lizard", and is derived from the Greek
Neustos- ("swimming") and -sauros ("lizard").
N. gigondarum. The holotype
material consists of only the posterior of trunk and the tail, discovered in France
. However, identifying metriorhynchid genera from post-cranials is not easy, as such until diagnostic material is discovered Neustosaurus is considered nomen dubium
. Neustosaurus has been considered a junior synonym of either Dakosaurus
and Geosaurus
over the past 100 years. In 2009, Young and Andrade published a re-description of Geosaurus, examining its relationships and the validity of species lumped into the genus. They concluded that Neustosaurus is a nomen dubium, but if new material was discovered it would be the senior synonym of Cricosaurus
.
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 marine crocodyliform from the Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
. Neustosaurus was a carnivore
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
that spent much, if not all, its life out at sea. No Neustosaurus eggs or nest have been discovered, so little is known of the reptile's lifecycle, unlike other large marine reptiles of the Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
, such as plesiosaur
Plesiosaur
Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods...
s or ichthyosaurs which are known to give birth to live young out at sea. Where Neustosaurus mated, whether on land or at sea, is currently unknown. The name Neustosaurus means "Swimming lizard", and is derived from the Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
Neustos- ("swimming") and -sauros ("lizard").
History of discovery
There is only a single described species within Neustosaurus, the type speciesType species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
N. gigondarum. The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
material consists of only the posterior of trunk and the tail, discovered in France
France
The 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...
. However, identifying metriorhynchid genera from post-cranials is not easy, as such until diagnostic material is discovered Neustosaurus is considered nomen dubium
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
. Neustosaurus has been considered a junior synonym of either Dakosaurus
Dakosaurus
Dakosaurus is an extinct genus within the family Metriorhynchidae that lived during the Late Jurassic and Early Cretaceous. It was large, with teeth that were serrated and compressed lateromedially . The genus was established by Friedrich August von Quenstedt in 1856 for an isolated tooth named...
and Geosaurus
Geosaurus
Geosaurus is an extinct genus of marine crocodyliform within the family Metriorhynchidae that lived during the Late Jurassic to the Early Cretaceous. Geosaurus was a carnivore that spent much, if not all, its life out at sea...
over the past 100 years. In 2009, Young and Andrade published a re-description of Geosaurus, examining its relationships and the validity of species lumped into the genus. They concluded that Neustosaurus is a nomen dubium, but if new material was discovered it would be the senior synonym of Cricosaurus
Cricosaurus
Cricosaurus is an extinct genus of marine crocodyliform belonging to the family Metriorhynchidae. The genus was established by Johann Andreas Wagner in 1858 for three skulls from the Tithonian of Germany...
.