Ichthyotitan
| Ichthyotitan Temporal range: Late Triassic (Rhaetian),
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|---|---|
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | †Ichthyosauria |
| Family: | †Shastasauridae (?) |
| Genus: | †Ichthyotitan |
| Species: | †I. severnensis
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| Binomial name | |
| †Ichthyotitan severnensis Lomax et al., 2024
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Ichthyotitan (meaning "fish giant") is an extinct genus of probable shastasaurid ichthyosaur from the Late Triassic (late Rhaetian) Westbury Mudstone Formation of Somerset, United Kingdom. The genus contains a single species, I. severnensis, known from two surangular bones. It may have had a body length near 25 metres (82 ft), making it the largest marine reptile currently known.[1]
Discovery
The first specimen that would later be referred as Ichthyotitan, BRSMG Cg2488 (the "Lilstock specimen"), was found in 2016 and described in 2018. It consists of a partial left surangular measuring 96 centimeters (3.15 ft) long.[1] In 2018, Dean Lomax, de la Salle, Judy Massare, and Ramues Gallois identified the Lilstock specimen as a shastasaurid. While its incompleteness made the size of the animal difficult to suggest, it clearly was very large. Using Shonisaurus sikanniensis as a model, the researchers estimated the ichthyosaur to have been 26 meters (85 ft) long, nearly the size of a blue whale. Scaling based on Besanosaurus, however, found a shorter length estimate of 22 meters (72 ft).[2] The 2024 study describing Ichthyotitan provided a revised length estimate of 25 metres (82 ft), making it one of if not probably the largest marine reptile ever described.[1]
The Ichthyotitan holotype specimen, BRSMG Cg3178, was discovered in sediments of the Westbury Formation near Blue Anchor in Somerset, UK. The first fragment was found in 2020, with subsequent expeditions until 2022 revealing additional pieces. The specimen consists of fragments of a right surangular. Histological features suggest that the specimen was either a subadult or a young adult.[1]
Other remains of giant ichthyosaurs from around the same time period have also been reported from Germany (Bonenburg) and France (Autun),[3] though their fragmentary nature means that they cannot be confidently assigned to Ichthyotitan.[1]
References
- ^ a b c d e Lomax, D. R.; de la Salle, P.; Perillo, M.; Reynolds, J.; Reynolds, R.; Waldron, J. F. (2024). "The last giants: New evidence for giant Late Triassic (Rhaetian) ichthyosaurs from the UK". PLOS ONE. 19 (4). e0300289. doi:10.1371/journal.pone.0300289.
- ^ Lomax, Dean R.; De la Salle, Paul; Massare, Judy A.; Gallois, Ramues (2018-04-09). Wong, William Oki (ed.). "A giant Late Triassic ichthyosaur from the UK and a reinterpretation of the Aust Cliff 'dinosaurian' bones". PLOS ONE. 13 (4): e0194742. Bibcode:2018PLoSO..1394742L. doi:10.1371/journal.pone.0194742. ISSN 1932-6203. PMC 5890986. PMID 29630618.
- ^ Perillo, Marcello; Sander, P. Martin (2024-04-09). "The dinosaurs that weren't: osteohistology supports giant ichthyosaur affinity of enigmatic large bone segments from the European Rhaetian". PeerJ. 12: e17060. doi:10.7717/peerj.17060. ISSN 2167-8359.
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