Abyssosaurus

Name: Abyssosaurus (Abyss lizard).
Phonetic: Ah-biss-so-sore-us.
Named By: A.‭ ‬Yu.‭ ‬Berezin‭ ‬-‭ ‬2011.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Sauropterygia,‭ ‬Plesiosauria,‭ ‬Cryptoclididae.
Species: A.‭ ‬nataliae‭ (‬type‭)‬.
Diet: Piscivore.
Size: Roughly estimated to have been about 7 meters long. Skull about 30 centimetres long
Known locations: Russia,‭ ‬Chuvashia/Chuvash Republic.
Time period: Hauterivian of the Cretaceous.
Fossil representation: Partial skull and post cranial remains.

       Abyssosaurus is a genus of plesiosaur that lived in Russia during the Early Cretaceous.‭ ‬At the time of its description Abyssosaurus was identified as a link between Late Jurassic forms such as Tatenectes and Kimmerosaurus,‭ ‬and Late Cretaceous forms such as Aristonectes and Kaiwhekea.‭ ‬A slightly later study in‭ ‬2013‭ ‬by Benson‭ & ‬Druckenmiller identified Abyssosaurus as a close relative of Colymbosaurus.
       Abyssosaurus is noted as having a strong level of pachyostosis in the gastralia‭ (‬belly ribs‭) ‬as well as the flippers.‭ ‬This is thought to have made Abyssosaurus less buoyant,‭ ‬but also more stable in turbulent waters.‭ ‬Abyssosaurus is also noted for having rear flippers larger than the front flippers.‭ ‬A theory put forward about Abyssosaurus and similar plesiosaurs‭ (‬Berezin,‭ ‬2019‭) ‬suggests that these creatures would be efficient divers comfortably capable of hovering at diagonal angles while they searched the sea floor for prey.

Further reading
-‭ ‬A new plesiosaur of the family Aristonectidae from the Early Cretaceous of the center of the Russian Platform.‭ ‬-‭ ‬Paleontological Journal‭ ‬45‭(‬6‭)‬:648-660.‭ ‬-‭ ‬A.‭ ‬Yu.‭ ‬Berezin‭ ‬-‭ ‬2011.
- Faunal turnover of marine tetrapods during the Jurassic-Cretaceous transition. - Biological Reviews. 89 (1): 1–23. - R. B. J. Benton & P. S. Druckenmiller - 2013.
- Craniology of the Plesiosaur Abyssosaurus nataliae Berezin (Sauropterygia, Plesiosauria) from the Lower Cretaceous of the Central Russian Platform. - Paleontological Journal. 52 (3): 328–341. - A. Y. Berezin - 2018.
- Morphofunctional features of the plesiosaur Abyssosaurus nataliae (Plesiosauroidea: Plesiosauria) in connection with adaptations to a deep-water lifestyle. - Ministry of National Resources and Ecology of the Russian Federation [in Russian]. - A. Berezin - 2019.

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