Ancalagon (worm)
| Ancalagon Temporal range: | |
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| Reconstruction of Ancalagon minor | |
| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Stem group: | Priapulida (?) |
| Class: | †Archaeopriapulida |
| Family: | †Ancalagonidae Conway Morris, 1977 |
| Genus: | †Ancalagon Conway Morris, 1977 |
| Species | |
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| Synonyms | |
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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 (worm) 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.