Tethysaurus
Encyclopedia
Tethysaurus was a genus
of mosasaur
from the Early Turonian
(Late Cretaceous
) period. The only species is Tethysaurus nopscai. The name means "Tethys' lizard of Nopsca", a reference to the Greek
goddess
of the sea Tethys
(also the name of the Tethys Ocean
, an ancient sea between southern Europe and northern Africa) and to the Hungarian paleontologist Baron
Ferenc Nopsca, who made pioneering studies on Adriatic aquatic squamates. It was found near the villages of Tadirhourst and Asflain in the region of Goumima, Errachidia Province, in Morocco
, with three referred specimens that included a nearly complete articulated skull, mandible, vertebrae and portions of the appendicular skeleton
. The diagnosis after Bardet et al. is "(...) prefrontal strongly vaulted in anterior view; parietal exhibits a triangular table ending posteriorly in two pointed pegs overlying the supraoccipital; jugal with a large and wide ascending ramus; medullar floor of the basioccipital pierced by three foramina; splenial with a large notched dorsomedial process; surangular exposed medially ventral to the coronoid; dental formula: 19-20 maxillary, 15-19 pterygoid and at least 19 dentary teeth; large paracotylar and parazygosphenal foramina on vertebrae."
An average-sized mosasaur of 3 metres (9.8 ft) length, Tethysaurus displays a number of basal
and derived
features that led to a initial classification as an intermediate stage between primitive aigialosaurids of the Cenomanian
and derived mosasaurids from the Turonian to the Maastrichtian
. More recent analysis put Tethysaurus in a clade
along Russellosaurus
and Yaguarasaurus
called the parafamily Russellosaurina, as a basal Turonian clade of Mosasauridae.
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 mosasaur
Mosasaur
Mosasaurs are large extinct marine lizards. The first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764...
from the Early Turonian
Turonian
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...
(Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
) period. The only species is Tethysaurus nopscai. The name means "Tethys' lizard of Nopsca", a reference to the Greek
Greek mythology
Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...
goddess
Goddess
A goddess is a female deity. In some cultures goddesses are associated with Earth, motherhood, love, and the household. In other cultures, goddesses also rule over war, death, and destruction as well as healing....
of the sea Tethys
Tethys (mythology)
In Greek mythology, Tethys , daughter of Uranus and Gaia was an archaic Titaness and aquatic sea goddess, invoked in classical Greek poetry but not venerated in cult. Tethys was both sister and wife of Oceanus...
(also the name of the Tethys Ocean
Tethys Ocean
The 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:...
, an ancient sea between southern Europe and northern Africa) and to the Hungarian paleontologist Baron
Baron
Baron is a title of nobility. The word baron comes from Old French baron, itself from Old High German and Latin baro meaning " man, warrior"; it merged with cognate Old English beorn meaning "nobleman"...
Ferenc Nopsca, who made pioneering studies on Adriatic aquatic squamates. It was found near the villages of Tadirhourst and Asflain in the region of Goumima, Errachidia Province, in Morocco
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...
, with three referred specimens that included a nearly complete articulated skull, mandible, vertebrae and portions of the appendicular skeleton
Appendicular skeleton
The Appendicular skeleton is composed of 126 bones in the human body. The word appendicular is the adjective of the noun appendage, which itself means a part that is joined to something larger...
. The diagnosis after Bardet et al. is "(...) prefrontal strongly vaulted in anterior view; parietal exhibits a triangular table ending posteriorly in two pointed pegs overlying the supraoccipital; jugal with a large and wide ascending ramus; medullar floor of the basioccipital pierced by three foramina; splenial with a large notched dorsomedial process; surangular exposed medially ventral to the coronoid; dental formula: 19-20 maxillary, 15-19 pterygoid and at least 19 dentary teeth; large paracotylar and parazygosphenal foramina on vertebrae."
An average-sized mosasaur of 3 metres (9.8 ft) length, Tethysaurus displays a number of basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
and derived
Derived
In phylogenetics, a derived trait is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary...
features that led to a initial classification as an intermediate stage between primitive aigialosaurids of the Cenomanian
Cenomanian
The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...
and derived mosasaurids from the Turonian to the Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
. More recent analysis put Tethysaurus in a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
along Russellosaurus
Russellosaurus
Russellosaurus is a basal mosasauroid from the Upper Cretaceous of North America. The genus was described from a skull discovered in an exposure of the Arcadia Park Shale at Cedar Hill, Dallas County in south-central Texas...
and Yaguarasaurus
Yaguarasaurus
Yaguarasaurus was a genus of mosasaur from the Late Cretaceous period of Colombia, South America. The remains discovered were defined as a new genus and species of the tribe Plioplatecarpini, Yaguarasaurus columbianus, by the Colombian paleontologist María Páramo, former director of the Museo de...
called the parafamily Russellosaurina, as a basal Turonian clade of Mosasauridae.