Emmonsaspis
| Emmonsaspis Temporal range: [1] | |
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| Life restoration of Emmonsaspis | |
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| Fossil of Emmonsaspis | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Genus: | †Emmonsaspis Resser & Howell, 1938 |
| Species | |
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Emmonsaspis is a Cambrian chordate, and its fossils were found in the Cambrian-age Parker Slate of Vermont in the late 19th century.
Description
[edit]Emmonsaspis is a chordate related to Metaspriggina and Nuucichthys. It grew to roughly 4.5 cm (1.8 in) in length and probably fed on plankton in the water column. No trace of a spinal cord is present, although roughly 50 myomeres can be seen in the fossils. It had large eyes and a large organ behind its branchial chamber, probably a liver.
There are two species: Emmonaspis worthanella and Emmonaspis cambriensis (Walcott(?) 1886(?) 1911(?)).
E. cambrensis has been described as a graptolite, a chordate, an arthropod and as a frond-like organism.[2][3]
Affinities
[edit]It was interpreted by paleontologist C. D. Walcott in 1911 as a polychaete worm. Although some paleontologists regarded it as an early chordate allied with Pikaia et al., Conway Morris suggested in 1993 that it might be a Cambrian descendant of the Vendian form Pteridinium, and a frondose morphology was accepted,[4] until a 2024 study found Emmonsaspis to be in a polytomy with Metaspriggina and Nuucichthys as a stem-group vertebrate.[1]
Notes
[edit]- 1 2 Lerosey-Aubril, R.; Ortega-Hernández, J. (2024). "A long-headed Cambrian soft-bodied vertebrate from the American Great Basin region". Royal Society Open Science. 11 (7) 240350. Bibcode:2024RSOS...1140350L. doi:10.1098/rsos.240350. PMC 11267725. PMID 39050723.
- ↑ "Cambrian Primitive Chordate Fossil". www.fossilmuseum.net. Retrieved 29 May 2018.
- ↑ "Duffy: Chordate Origins". www.biology.ualberta.ca. Archived from the original on 21 February 2008. Retrieved 29 May 2018.
- ↑ Shu, D. -G.; Conway Morris, S.; Zhang, X. -L. (1996). "A Pikaia-like chordate from the Lower Cambrian of China". Nature. 384 (6605): 157–158. Bibcode:1996Natur.384..157S. doi:10.1038/384157a0.
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