Emmonsaspis

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

Emmonsaspis Temporal range: Cambrian Stage 4 PreꞒ Ꞓ O S D C P T J K Pg N [1]
Reconstruction of Emmonsaspis
Fossil of Emmonsaspis
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Genus:	†Emmonsaspis Resser & Howell, 1938
Species
Emmonaspis worthanella Resser & Howell, 1938 Emmonsaspis cambrensis (Walcott, 1891)

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.^[2][3]

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,^[4] until a 2024 study found Emmonsaspis to be in a polytomy with Metaspriggina and Nuucichthys as a stem-group vertebrate.^[1]