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Jamoytius
| Jamoytius Temporal range: Llandovery Epoch to Wenlock Epoch,
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Order: | †Jamoytiiformes |
| Family: | †Jamoytiidae |
| Genus: | †Jamoytius |
| Species: | †J. kerwoodi
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| Binomial name | |
| †Jamoytius kerwoodi White, 1946[1]
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Jamoytius kerwoodi is an extinct species of primitive, eel-like jawless fish known from the Patrick Burn Formation in Scotland, dating to the Llandovery epoch of the Early Silurian period.
Long thought of as a "basal anaspid," J. kerwoodi is now recognized as the best-known member of the Hyperoartian order Jamoytiiformes. It had an elongated body, and is thought to have had, in comparison with relatives known from intact bodies like Euphanerops, a dorsal fin and an anal fin near the rearmost third of its body. Earlier reconstructions depict the creature as having side-fins running the length of its body, starting from behind the branchial openings to the tip of its tail: new research demonstrates that such "fins" are actually deformations of the bodywall as the corpse was being squished post-burial.[2] In life, J. kerwoodi resembled a lamprey with a very small mouth. Because the fossil had no teeth, teeth-like structures, nor suggestions of either in its mouth, it was not carnivorous like many modern lampreys. It was more likely to have been a filter-feeder or a detritus-feeder, possibly in the manner of larval lampreys.
The fish had a cartilaginous skeleton, and a branchial basket resembling the cyclostomes - features that suggest that it was a basal member of that clade. It is also the earliest known vertebrate with camera-type eyes.[3] It also possessed weakly mineralised scales.[4]
- ^ White, E.I. (March 1, 1946). "Jamoytius kerwoodi, a new chordate from the Silurian of Lanarkshire [Scotland]". Geological Magazine. 83 (2): 89–97. doi:10.1017/S0016756800082856. S2CID 86329654. Retrieved 2007-10-31.
- ^ Cite error: The named reference
sansomwas invoked but never defined (see the help page). - ^ Ritchie, A. (1968). "New evidence on Jamoytius kerwoodi White, an important ostracoderm from the Silurian of Lanarkshire, Scotland" (PDF). Palaeontology. 11: 21–39. Archived from the original (PDF) on 2011-07-16. Retrieved 2007-10-31.
- ^ Today, G.; Blom, Henning; Märss, Tiiu (2003). "Fossils explained 43: Anaspid fishes". Geology Today. 19 (3): 111–113. doi:10.1046/j.1365-2451.2003.00413.x. S2CID 129511577.
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