''Opthalmothule'' (meaning "eye of the north"), was a cryptoclidid

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 ...

dating to the latest Volgian (around the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

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 th ...

boundary), found in the Slottsmøya Member

Lagerstätte A Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that exhibits extraordinary fossils with exceptional preservation—sometimes including preserved soft tissues. These for ...

of the

Agardhfjellet Formation The Agardhfjellet Formation is a Formation (geology), geologic formation in Svalbard, Norway. It preserves fossils dating back to the Oxfordian (stage), Oxfordian to Berriasian stages, spanning the Late Jurassic-Early Cretaceous boundary. The form ...

Spitsbergen Spitsbergen (; formerly known as West Spitsbergen; Norwegian: ''Vest Spitsbergen'' or ''Vestspitsbergen'' , also sometimes spelled Spitzbergen) is the largest and the only permanently populated island of the Svalbard archipelago in northern Norw ...

. The type species is ''O. cryostea''.

Description

''Opthalmothule'' was a medium-sized plesiosaur, measuring long. It was noted to have unusually large eye sockets, which suggests a paleobiological specialization, such as deep water and/or nocturnal hunting. Along with ''

Abyssosaurus ''Abyssosaurus'' is an extinct genus of cryptoclidid plesiosaur known from the Early Cretaceous of Chuvash Republic, western Russia. It possessed a shortened skull, and it has been suggested that it primarily inhabited the bathyal zone. Discove ...

'', it is one of the youngest cryptoclidids known from

boreal Boreal may refer to: Climatology and geography *Boreal (age), the first climatic phase of the Blytt-Sernander sequence of northern Europe, during the Holocene epoch *Boreal climate, a climate characterized by long winters and short, cool to mild ...

regions. The holotype is known from skeletal material that includes a complete cranium and a partial mandible, a complete and articulated cervical vertebrae, a set of pectoral and anterior to middle dorsal series, and the pectoral girdle and anterior humeri.

References

Cryptoclidids Tithonian life Plesiosaurs of Europe Late Jurassic reptiles of Europe Jurassic Norway Fossils of Svalbard Agardhfjellet Formation Fossil taxa described in 2020 Sauropterygian genera {{Plesiosaur-stub