Ancalagon minor
extinct species of priapulid worms
Ancalagon minor is an extinct priapulid worm known from the Cambrian Burgess Shale.
Because it superficially resembles the modern-day internal parasites known as the acanthocephalids or "spiny-headed worms," A. minor was once thought to be, or once thought to resemble the hypothetical free-living ancestor of acanthocephalids. Two specimens of Ancalagon are known from the Greater Phyllopod bed, where they comprise < 0.01% of the community.
Along with the other Cambrian worms such as Ottoia, Selkirkia, Louisella, Fieldia, Scolecofurca, and Lecythioscopa, the organism may fall into a clade termed "Archaeopriapulida," a stem group to the Priapulids proper. However, the morphological similarity of these organisms to their modern cousins is remarkable, especially for the Burgess Shale. A phylogenetic analysis does not provide a great deal of resolution to the relationships between these basal worms.
Etymology
The generic name is a homage to the dragon Ancalagon of J.R.R. Tolkien's Middle-earth legendarium, in reference to the worm's prominent rows of hooks on its proboscis. The species was previously placed in the genus Ottoia, as Ottoia minor, but was removed by Simon Conway Morris, who noted morphological differences.
Morphology
Ancalagon had a slender, cyndrical, radially symmetric body averaging 6 centimeters in length. Its proboscis was armed with circum-oral hooks at the anterior.
Begin with the source’s own compact description: “Ancalagon minor” is extinct species of priapulid worms. The dossier treats that line as a proposition to test through Ancalagon, minor and extinct, not as a finished interpretation.
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This entry incorporates text from “Ancalagon minor” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.