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Emmonsaspis

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Emmonsaspis
Temporal range: Cambrian Stage 4
[1]
Fossil of Emmonsaspis
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Genus: Emmonsaspis
Resser & Howell, 1938
Species
  • Emmonaspis worthanella Resser & Howell, 1938
  • Emmonsaspis cambrensis (Walcott, 1891)

Emmonsaspis is a Cambrian chordate, and its fossils were found in the Cambrian-age Parker Slate of Vermont in the late 19th century.

Description

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Emmonsaspis is described as a tadpole or worm-like animal. No trace of a spinal cord is present, although myomeres can be seen in the fossils.

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

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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 basal chordate. [1]

Notes

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  1. ^ a b 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). doi:10.1098/rsos.240350. PMC 11267725.
  2. ^ "Cambrian Primitive Chordate Fossil". www.fossilmuseum.net. Retrieved 29 May 2018.
  3. ^ "Duffy: Chordate Origins". www.biology.ualberta.ca. Retrieved 29 May 2018.
  4. ^ 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. doi:10.1038/384157a0.