''Thililua'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

polycotylid Polycotylidae is a family of plesiosaurs from the Cretaceous, a sister group to Leptocleididae. Polycotylids first appeared during the Albian stage of the Early Cretaceous, before becoming abundant and widespread during the early Late Cretaceous. ...

plesiosaur The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared ...

, containing one

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

, ''T. longicollis''.

Discovery

The name ''Thililua'' is derived from that of an ancient aquatic god from local

Berber Berber or Berbers may refer to: Ethnic group * Berbers, an ethnic group native to Northern Africa * Berber languages, a family of Afro-Asiatic languages Places * Berber, Sudan, a town on the Nile People with the surname * Ady Berber (1913–196 ...

mythology; ''longicollis'' refers to the animal's long neck. ''Thililua'' has been found in

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

(early

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 93.9 ± 0.8 Ma and 89.8 ± 1 Ma (million years ago). The Turonian is preceded by t ...

) rocks in the

High Atlas High Atlas, also called the Grand Atlas ( ar, الأطلس الكبير, Al-Aṭlas al-Kabīr; french: Haut Atlas; shi, ⴰⴷⵔⴰⵔ ⵏ ⴷⵔⵏ ''Adrar n Dern''), is a mountain range in central Morocco, North Africa, the highest part of t ...

mountains of

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 to ...

in north

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

. ''Thililua'' is the first Polycotylid plesiosaur discovered in Africa, and also the first discovered that lived at a

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...

latitude. In 2010, ''Thililua'' was transferred to

Leptocleididae Leptocleididae is a family of small-sized plesiosaurs that lived during the Early Cretaceous period (early Berriasian to early Albian stage). They had small bodies with small heads and short necks. ''Leptocleidus'' and '' Umoonasaurus'' had round ...

as a sister taxon to ''

Nichollssaura ''Nichollssaura'' is an extinct genus of leptocleidid plesiosaur from the Early Cretaceous Boreal Sea of North America. The type species is ''N. borealis'', found in the early Albian age Clearwater Formation near Fort McMurray, Alberta, Canada. ...

''.

Description

The type specimen of ''T. longicollis'', which was described in

2003 File:2003 Events Collage.png, From top left, clockwise: The crew of STS-107 perished when the Space Shuttle Columbia disintegrated during reentry into Earth's atmosphere; SARS became an epidemic in China, and was a precursor to SARS-CoV-2; A des ...

, consists of an almost complete

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

and

lower jaw In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

, articulated with 37

vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic i ...

. Of these vertebrae, 30 were cervical (neck) vertebrae, which is an unusually high number compared to other Polycotylids, such as ''

Dolichorhynchops ''Dolichorhynchops'' is an extinct genus of polycotylid plesiosaur from the Late Cretaceous (early Turonian to late Campanian stage) of North America, containing three species, ''D. osborni'', ''D. bonneri'' and ''D. tropicensis'', as well as a ...

'', which had only 19 neck vertebrae, and ''

Polycotylus ''Polycotylus'' is a genus of plesiosaur within the family Polycotylidae. The type species is ''P. latippinis'' and was named by American paleontologist Edward Drinker Cope in 1869. Eleven other species have been identified. The name means 'much- ...

'', which had 26. It is believed to be an adult specimen, since some of the

cranial sutures In anatomy, fibrous joints are joints connected by fibrous tissue, consisting mainly of collagen Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of c ...

are very difficult to distinguish. Using comparisons with the head and neck length to body length ratio of a related genus, ''

'', the estimated total length of ''Thililua'' was 5.5 to 6 metres.

References

{{Taxonbar, from=Q16743868, from2=Q958323 Fossils of Morocco Late Cretaceous plesiosaurs Plesiosaurs of Africa Polycotylids Fossil taxa described in 2003 Sauropterygian genera

Discovery

Description

See also

References