''Ancalagon minor'' is an extinct

priapulid Priapulida (priapulid worms, from Gr. πριάπος, ''priāpos'' 'Priapus' + Lat. ''-ul-'', diminutive), sometimes referred to as penis worms, is a phylum of unsegmented marine worms. The name of the phylum relates to the Greek god of fertility ...

worm known from the Cambrian

Burgess Shale The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is famous for the exceptional preservation of the soft parts of its fossils. At old (middle Cambrian), it is one of the earliest foss ...

. 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 The Phyllopod bed, designated by USNM locality number 35k, is the most famous fossil-bearing member of the Burgess Shale fossil ''Lagerstätte''. It was quarried by Charles Walcott from 1911–1917 (and later named Walcott Quarry), and was t ...

, where they comprise < 0.01% of the community. Along with the other Cambrian worms such as ''

Ottoia ''Ottoia'' is a stem-group archaeopriapulid worm known from Cambrian fossils. Although priapulid-like worms from various Cambrian deposits are often referred to ''Ottoia'' on spurious grounds, the only clear ''Ottoia'' macrofossils come from th ...

'', ''

Selkirkia ''Selkirkia'' is a genus of predatory, tubicolous priapulid worms known from the Middle Cambrian Burgess Shale, Ogygopsis Shale and Puncoviscana Formation. 142 specimens of ''Selkirkia'' are known from the Greater Phyllopod bed, where they compr ...

Louisella ''Louisella'' is a genus of worm known from the Middle Cambrian Burgess Shale. It was originally described by Charles Walcott in 1911 as a holothurian echinoderm, and represents a senior synonym of ''Miskoia'', which was originally described as ...

'', '' Fieldia'', ''

Scolecofurca ''Scolecofurca'' is a genus of stem-group priapulid worm dating from the Middle Cambrian period approximately 505 million years ago. It is known from a single fossil specimen from the Raymond Quarry in the Burgess Shale The Burgess Shale ...

'', and ''

Lecythioscopa ''Lecythioscopa'' is a genus of probable archaeopriapulid known from two specimens from the Walcott Quarry from the Middle Cambrian Burgess Shale. Morphology The specimens of ''Lectythioscopa'' are both missing their posterior portions, leavi ...

'', 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 John Ronald Reuel Tolkien (, ; 3 January 1892 – 2 September 1973) was an English writer and philologist. He was the author of the high fantasy works ''The Hobbit'' and ''The Lord of the Rings''. From 1925 to 1945, Tolkien was the Rawlins ...

Middle-earth Middle-earth is the fictional setting of much of the English writer J. R. R. Tolkien's fantasy. The term is equivalent to the ''Miðgarðr'' of Norse mythology and ''Middangeard'' in Old English works, including ''Beowulf''. Middle-earth is t ...

legendarium Tolkien's legendarium is the body of J. R. R. Tolkien's mythopoeic writing, unpublished in his lifetime, that forms the background to his ''The Lord of the Rings'', and which his son Christopher summarized in his compilation of ''The Silmarill ...

, in reference to the worm's prominent rows of hooks on its

proboscis A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elong ...

. The species was previously placed in the genus ''

'', as ''Ottoia minor'', but was removed by

Simon Conway Morris Simon Conway Morris (born 1951) is an English palaeontologist, evolutionary biologist, and astrobiologist known for his study of the fossils of the Burgess Shale and the Cambrian explosion. The results of these discoveries were celebrated in ...

, 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. There were about 10 of these hooks, equal in size and with prominent bases. Directly posterior was an unarmed space, followed by posteriorly directed spinose hooks. The trunk is annulated with 0.2 to 0.25 millimeter spacing, and carried rows of setae possibly performing sensory functions. The apparent absence of retractor muscles correlates with ''Ancalagons inability to significantly invert its proboscis. The organism was probably a burrowing predator.

References

External links

"Ancalagon minor"
Burgess Shale Fossil Gallery. Virtual Museum of Canada. 2011. (Burgess Shale species 96) {{DEFAULTSORT:Ancalagon (animal) Burgess Shale fossils Priapulida Cambrian genus extinctions Burgess Shale animals Fossil taxa described in 1977 Fossil taxa described in 1911 Organisms named after Tolkien and his works

Etymology

Morphology

See also

References

External links