A black reconstruction silhouette of an elongated swimming animal with broad side fins, an eye opening and two long forward appendages.
Attributed silhouette labelled Nectocaris pteryx in the individual source record; retained whole raster shows an outline, without colour, exact locality or diagnostic detail. This is an artist reconstruction, not fossil photography or proof of disputed phylogenetic affinity; outline reflects the credited interpretation.
Overview
Conway Morris formally described Nectocaris pteryx in 1976 from a Smithsonian holotype, USNM 198667. Walcott collected his isolated specimen at an unknown date between 1909 and 1924. The species is known from the Walcott, Raymond and Collins quarries of the Burgess Shale, and about 90 specimens are cited.
The body is kite-shaped, with two forward tentacles, stalked eyes, lateral fins and an axial cavity; the largest reported individual reaches 72 mm including tentacles. Specimen ROM 59656 preserves a funnel-like structure and a small trilobite inside the body. The animal is inferred to have swum and taken prey or scavenged.
Its placement has shifted repeatedly. Earlier comparisons with arthropods and chordates gave way to a 2010 cephalopod interpretation, challenged by more recent evidence. A 2025 study by Vinther and colleagues described phosphatized arcuate structures, read as a ventral ganglion, in Nektognathus from Sirius Passet. With jaws, lateral fins, a subterminal anus and anterior antennae, this links nectocaridids to stem chaetognaths, alongside Timorebestia and Amiskwia. The neural evidence comes from Nektognathus, not Nectocaris.
Origins & earliest records
Formally described by Conway Morris in 1976 from Burgess Shale material about 505 million years old.
Evidence & interpretation
Burgess Shale compression fossils with gut contents; family-level affinity rests on neural and anatomical evidence from a related nectocaridid.
Selected bibliography
Documented works and useful reading. This is not a list of every appearance.
- 01
A fossilized ventral ganglion reveals a chaetognath affinity for Cambrian nectocaridids
Selected bibliography; family-level chaetognath affinity based on Nektognathus.
Family, evolution & connections
Taxonomic classification
A hierarchy of classified groups, not a chain of direct ancestors.
Source note: Stem-chaetognath affinity is applied at family level following Vinther and colleagues 2025.
- familyNectocarididae
References
Sources supporting this profile. Linked pages have their own scope and editorial standards.
- Museum species pagenectocaris pteryxResearch access: 2026-10-06
- Institutional repository abstractA fossilized ventral ganglion reveals a chaetognath affinity for Cambrian nectocarididsResearch access: 2026-10-06
Image credits
Attributed silhouette reconstructionA black reconstruction silhouette of an elongated swimming animal with broad side fins, an eye opening and two long forward appendages.
Attributed silhouette labelled Nectocaris pteryx in the individual source record; retained whole raster shows an outline, without colour, exact locality or diagnostic detail. This is an artist reconstruction, not fossil photography or proof of disputed phylogenetic affinity; outline reflects the credited interpretation.