Omphalosaurus: Research Database
Ichthyosauria (Sauropterygia) · Middle Triassic (~245-240 MYA) · North America — USA, Nevada (Prida Formation)
Research Note: Omphalosaurus was an early ichthyosaur from the Middle Triassic of Nevada — one of the oldest known ichthyosaurs and an important taxon for understanding the early evolution of ichthyosaurs and the recovery of marine ecosystems after the Permian-Triassic extinction.
| Research Finding | Status | Grade | Year | Method | Citation | Impact |
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Jiang et al. 2003: Omphalosaurus and new data on early ichthyosaurs from the Triassic of Nevada
Jiang et al. 2003 provide comprehensive data on Omphalosaurus from the Middle Triassic of Nevada, establishing it as an early ichthyosaur and documenting early ichthyosaur diversity in the Triassic of North America
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Confirmed | A | 2003 | Fossil | Jiang et al., Neues Jahrbuch für Geologie und Paläontologie | Taxonomy |
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Maisch & Matzke 2003: Omphalosaurus and additional data on early ichthyosaur anatomy and relationships
Maisch & Matzke 2003 provide additional data on Omphalosaurus and early ichthyosaur anatomy and relationships, further contextualising its significance within Ichthyosauria
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Confirmed | B | 2003 | Fossil | Maisch & Matzke, Neues Jahrbuch für Geologie und Paläontologie | Anatomy |
Active Debate: Early Ichthyosaur Evolution and the Triassic Marine Revolution
Whether Omphalosaurus was a fully aquatic ichthyosaur or retained terrestrial adaptations is debated. The early evolution of ichthyosaurs in the Triassic — and their relationships to other marine reptiles — is key to understanding marine reptile history.
What We Still Do Not Know About Omphalosaurus
- Complete skeletal morphology: Partial specimens known.
- Diet: Likely marine prey.
- Swimming style: Debate ongoing.
- Social behavior: No direct evidence.
In Depth
Since the genus was first named from fossils in Nevada, USA, Omphalosaurus was usually perceived as a small and primitive ichthyosaur that lived during the early Triassic. Towards the end of the twentieth and early twenty-first centuries however questions were raised about the genus being an ichthyosaur with notes about how the known fossils of Omphalosaurus don’t show any feature that are exclusive just to the ichthyosaurs. Most of this doubt was highlighted in a paper by Motani and published in 2000, however since this papers by Sander and Faber in 2003, and Maisch in 2010, both describing new specimens of Omphalosaurus, have concluded that Omphalosaurus is a primitive ichthyosaur.
One thing that we can be a little more certain about Omphalosaurus is the diet. The teeth of Omphalosaurus are blunt and rounded, and usually these kinds of teeth are seen in animals that eat hard bodied items. In reference to Omphalosaurus specifically this would be shellfish which would have had their hard outer shells broken up by the teeth so that the soft inside could then be swallowed by the feeding Omphalosaurus.
Further Reading
- Preliminary note on a new marine reptile from the Middle Triassic of Nevada. University of California Publications in Geological Sciences 5(5):71-79. - J. C. Merriam - 1906. - New finds of Omphalosaurus and a review of Triassic ichthyosaur paleobiogeography. - Palaeontologische Zeitschrift 72(1/2):149-162. - P. M. Sander & C. Faber - 1998. - Is Omphalosaurus ichthyopterygian? - A phylogenetic perspective. Journal of Vertebrate Paleontology 20(2): 295-301. - Ryosuke Motani - 2000. - The Triassic marine reptile Omphalosaurus: osteology, jaw anatomy, and evidence for ichthyosaurian affinities. - Journal of Vertebrate Paleontology Volume 23, Issue 4. - P. Martin Sander & Christiane Faber - 2003. - Phylogeny, systematics, and origin of the Ichthyosauria - the state of the art. - Palaeodiversiry 3: 151-214. - M. Maisch - 2010. – Two Records of Omphalosaurus from the Muschelkalk – The Reconstruction of Triassic Marine Ecosystems Based on Teeth. – International Symposium on Paleohistology. – Tanja Wintrich & Martin Sander – 2015. – Preliminary report on ichthyopterygian elements from the Early Triassic (Spathian) of Spitsbergen. – Norwegian Journal of Geology. – Christina Ekeheien, Lene Delsett, Aubrey Roberts & Hurum J�rn – 2018.
