''Eremiasaurus'' is a genus of extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

marine lizard belonging to the

mosasaur Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Ancient Greek, Greek ' meaning 'lizard') comprise a group of extinct, large marine reptiles from the Late Cretaceous. Their first fossil remains were discovered in a limestone quarry at Ma ...

family. It is classified as part of the

Mosasaurini Mosasaurini is a extinct Tribe (biology), tribe of Mosasaurinae, mosasaurine mosasaurs who lived during the Late Cretaceous and whose fossils have been found in North America, South America, Europe, Africa and Oceania, with questionable occurrenc ...

tribe (within the

Mosasaurinae The Mosasaurinae are a subfamily of mosasaurs, a diverse group of Late Cretaceous marine squamates. Members of the subfamily are informally and collectively known as "mosasaurines" and their fossils have been recovered from every continent excep ...

) and is exclusively known from the

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interv ...

phosphates of the

Ouled Abdoun Basin The Oulad Abdoun Basin (also known as the Ouled Abdoun Basin or Khouribga Basin) is a phosphate sedimentary basin located in Morocco, near the city of Khouribga. It is the largest in Morocco, comprising 44% of Morocco's phosphate reserves, and a ...

Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria ...

. ''Eremiasaurus'' means "desert lizard", referring to the arid climate of present-day

where its fossils were recovered. One species is known, ''E. heterodontus'', whose specific name refers to high degree of

heterodont In anatomy, a heterodont (from Ancient Greek, Greek, meaning 'different teeth') is an animal which possesses more than a single tooth morphology (biology), morphology. In vertebrates, heterodont pertains to animals where teeth are differentiate ...

y exhibited compared to other species of mosasaur. It was a medium-sized mosasaur, with the largest specimen measuring around in length.

Description

''Eremaiasaurus'' is known from two specimens UALVP 51744 and OCP DEK/GE 112, both designated as

syntype In biological nomenclature, a syntype is any one of two or more biological types that is listed in a description of a taxon where no holotype was designated. Precise definitions of this and related terms for types have been established as part of ...

specimens due to the fact that UALVP 51744 lacks precise locality data. The syntype specimen UALVP 51744 belongs to an individual about long, consisting of a nearly complete skull, vertebral column and isolated pieces of the appendicular skeleton. The syntype specimen OCP DEK/GE 112, belonging to a larger long individual, also includes a nearly complete skull as well as a nearly complete vertebral column. Based on observations of these specimens, several distinguishing features can be established that clearly support ''Eremiasaurus'' as a distinct genus. The most prominent of these is the high degree of

y and the unusually large number of pygal vertebrae, only ''

Plotosaurus ''Plotosaurus'' ("swimmer lizard") is an extinct genus of mosasaur from the Upper Cretaceous (Maastrichtian) of Fresno County, California. Originally named ''Kolposaurus'' (meaning "bay lizard") by Berkeley paleontologist Charles Lewis Camp in 19 ...

'' is known to have possessed more pygal vertebrae.

Classification

An analysis carried out at the time of its description featuring a data matrix of 135 characters and 32 terminal taxa recovered ''Eremiasaurus heterodontus'' as a sister taxon to the Plotosaurini, a tribe now seen as synonymous with the

. A close relation to (or even inclusion within) the Mosasaurini is supported by the presence of an internarial bar keel, the exclusion of the prefrontals from the narial borders, narial embayments in the frontal and the presence of a quadrate ala groove. ''Eremiasaurus'' differs from the closely related ''

Mosasaurus ''Mosasaurus'' (; "lizard of the Meuse River") is the type genus (defining example) of the mosasaurs, an extinct group of aquatic squamate reptiles. It lived from about 82 to 66 million years ago during the Campanian and Maastrichtian stages ...

'' and ''

'' in having the infrastapedial and suprastapedial processes of the quadrate fused, possessing a very large and rounded stapedial pit, large pterygoid teeth and the glenoid condyle of the humerus being gently domed.

Cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

of ''Eremiasaurus'' and related taxa within the

modified from D.V. Grigoriev, 2013:Grigoriev, D. V. (2013). Redescription of ''Prognathodon lutugini'' (Squamata, Mosasauridae). ''Proceedings of the Zoological Institute RAS'', 317(3): 246-261.

References

{{Taxonbar, from=Q2919749 Mosasaurines Mosasaurs of Africa Fossil taxa described in 2012