Biology:Emmonsaspis
Emmonsaspis is a Cambrian chordate, and its fossils were found in the Cambrian-age Parker Slate of Vermont in the late 19th century.
Description
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.[1][2]
Affinities
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,[3] until a 2024 study found Emmonsaspis to be in a polytomy with Metaspriggina and Nuucichthys as a stem-group vertebrate.[4]
Notes
- ↑ "Cambrian Primitive Chordate Fossil". http://www.fossilmuseum.net/Cambrian-Explosion/Chordate/Chordate.htm.
- ↑ "Duffy: Chordate Origins". http://www.biology.ualberta.ca/courses.hp/biol606/OldLecs/Lecture2K.08.Duffy.html.
- ↑ 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. Bibcode: 1996Natur.384..157S.
- ↑ Cite error: Invalid
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Wikidata ☰ Q5373604 entry
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