In today's article we will explore the fascinating world of Shonisaurus and discover its many facets and meanings. Shonisaurus is a topic that has captivated humanity since time immemorial, its aspects and characteristics have been the object of study, debate and reflection throughout history. Through this article, we will delve into the different approaches and perspectives that have been given to Shonisaurus, from its impact on society to its relevance on a personal level. Get ready to immerse yourself in a journey of discovery and learning about Shonisaurus, a topic that undoubtedly invites us to reflect and question our own reality.
Shonisaurus is a genus of very large ichthyosaurs. At least 37 incomplete fossil specimens of the marine reptile have been found in the Luning Formation of Nevada, USA. This formation dates to the late Carnian age of the late Triassic period, about 237–227 million years ago.
Description
Shonisaurus lived during the Carnian stage of the late Triassic period. With a large skull about 2.75 m (9.0 ft) long, S. popularis and measured around 13.5–15 metres (44–49 ft) in length and 21.6–29.7 metric tons (23.8–32.7 short tons) in body mass.S. sikanniensis was one of the largest marine reptiles of all time, measuring 21 metres (69 ft) and weighing 81.5 metric tons (89.8 short tons).
Shonisaurus had a long snout, and its flippers were much longer and narrower than in other ichthyosaurs. While Shonisaurus was initially reported to have had socketed teeth (rather than teeth set in a groove as in more advanced forms), these were present only at the jaw tips, and only in the very smallest, juvenile specimens. All of these features suggest that Shonisaurus may be a relatively specialised offshoot of the main ichthyosaur evolutionary line. More recent finds however indicate that Shonisaurus possessed teeth in all ontogenetic stages. Robust sectorial teeth and gut contents indicate that Shonisaurus was a macrophagous raptorial
predator which fed on vertebrates and shelled mollusks like cephalopods, possibly even large-bodied prey. Additionally, Shonisaurus was historically depicted with a rather rotund body, but studies of its body shape since the early 1990s have shown that the body was much more slender than traditionally thought, and had a relatively deep body compared with related marine reptiles.
History
Fossils of Shonisaurus were first found in a large deposit in Nevada in 1920. Thirty years later, they were excavated, uncovering the remains of 37 very large ichthyosaurs. These were named Shonisaurus, which means "lizard from the Shoshone Mountains", after the formation where the fossils were found.
A second species from British Columbia was named Shonisaurus sikanniensis in 2004. However, a phylogenetic study by Sander and colleagues in 2011 later showed S. sikanniensis to be a species of Shastasaurus rather than Shonisaurus.
A subsequent study by Ji and colleagues published in 2013 reasserted the original classification, finding it more closely related to Shonisaurus than to Shastasaurus. Support for both hypotheses has been found in later studies, with some authors classifying the species in Shonisaurus and others in Shastasaurus. Specimens belonging to S. sikanniensis have been found in the Pardonet FormationBritish Columbia, dating to the middle Norian age (about 210 million years ago).
^ abcdeNicholls, Elizabeth L.; Manabe, Makoto (2004). "Giant Ichthyosaurs of the Triassic—A New Species of Shonisaurus from the Pardonet Formation (Norian: Late Triassic) of British Columbia". Journal of Vertebrate Paleontology. 24 (4): 838–849. doi:10.1671/0272-4634(2004)024[0838:GIOTTN]2.0.CO;2. ISSN0272-4634.
^McGowan, C.; Motani, R. (1999). "A Reinterpretation Of the Upper Triassic Ichthyosaur Shonisaurus". Journal of Vertebrate Paleontology. 19 (1): 42–49. doi:10.1080/02724634.1999.10011121.
^Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. pp. 78–79. ISBN1-84028-152-9.
^Kosch, Bradley F. (1990). "A revision of the skeletal reconstruction of Shonisaurus popularis (Reptilia: Ichthyosauria)". Journal of Vertebrate Paleontology. 10 (4): 512–514. doi:10.1080/02724634.1990.10011833.
^Hilton, Richard P. (2003). Dinosaurs and Other Mesozoic Animals of California. University of California Press, Berkeley. pp. 90–91. ISBN0-520-23315-8.
^Ji, C.; Jiang, D. Y.; Motani, R.; Hao, W. C.; Sun, Z. Y.; Cai, T. (2013). "A new juvenile specimen of Guanlingsaurus (Ichthyosauria, Shastasauridae) from the Upper Triassic of southwestern China". Journal of Vertebrate Paleontology. 33 (2): 340. doi:10.1080/02724634.2013.723082. S2CID83784699.
^Moon, B. (2019). "A new phylogeny of ichthyosaurs (Reptilia: Diapsida)". Journal of Systematic Palaeontology. 17: 1–27.
McGowan, Chris; Motani, Ryosuke (1999). "A reinterpretation of the Upper Triassic ichthyosaurShonisaurus". Journal of Vertebrate Paleontology. 19: 42–49. doi:10.1080/02724634.1999.10011121.
Motani, Ryosuke; Minoura, Nachio; Ando, Tatsuro (1998). "Ichthyosaurian relationships illuminated by new primitive skeletons from Japan". Nature. 393 (6682): 255–257. Bibcode:1998Natur.393..255M. doi:10.1038/30473. S2CID4416186.