Fossil Gallery

Home > Fossil Gallery > Ancalagon

Ancalagon minor

A worm bearing the name of a dragon

Line drawings of the appendages of the anomalocarids.

Get Adobe Flash player

Ancalagon minor (USNM 57646) – Holotype (part and counterpart). Left, plate 22 of Walcott (1911), showing a retouched image of the original specimen (upside down) (figure 5). Right, images of the same specimen showing a dark stain, probably representing decay fluids at the posterior end of the body. Specimen length = 70 mm. Specimen dry – direct light (top), dry – polarized light (middle, bottom). Walcott Quarry.

© Smithsonian Institution – National Museum of Natural History. Photos: Jean-Bernard Caron

Media 1 of 2 for Ancalagon minor Photo
Media 2 of 2 for Ancalagon minor Photo

Taxonomy

Kingdom:

Animalia

Phylum:

Priapulida

Class:

Unranked clade (stem group priapulids)

Affinity:

Ancalagon belongs to the priapulid worm stem group (Harvey et al., 2010; Wills, 1998).

Species name:

Ancalagon minor

Described by:

Walcott

Description date:

1911

Etymology:

Ancalagon – from Ancalagon the Black, a dragon in Tolkien’s fantasy writings (The Fellowship of the Ring, 1954; The Silmarillion, 1977), in reference to the worm’s strong rows of hooks.

minor – from the Latin minor, “inferior,” in reference to the small size of the worm.

Type Specimens:

Holotype –USNM57646 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.

Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Back to top

Age

Period:

Middle Cambrian, Bathyuriscus-Elrathina Zone (approximately 505 million years ago).

Back to top

Localities

Principal localities:

The Walcott Quarry on Fossil Ridge.

Back to top

History of Research

Brief history of research:

Walcott (1911, 1931) described and illustrated several specimens of this species as “Ottoia minor.” However, this species was pulled from the genus Ottoia to Ancalagon by Conway Morris (1977) and re-described as a primitive priapulid worm; later studies showed that it belongs to the priapulid stem group (Harvey et al., 2010; Wills, 1998).

Back to top

Description

Morphology:

The tubular body of this worm can reach up to 11 centimeters and is divided into a finely annulated trunk and an anterior eversible mouthpart, called a proboscis. The proboscis bears strong hooks at the front, and smaller hooks pointing backwards posteriorly. Fine hair-like setae are present on the trunk. The gut is straight and the anus is terminal.

Abundance:

This species is rare – less than 20 specimens are known.

Maximum size:

110 mm

Back to top

Ecology

Life habits:

Endobenthic, mobile

Feeding strategies:

Carnivorous

Ecological Interpretations:

The tubular body-shape is well adapted for burrowing; Ancalagon probably used its spines to pull itself through the mud. The strong hooks at the front of the proboscis suggest a carnivorous feeding habit.

Back to top

References

Bibliography:

CONWAY MORRIS, S. 1977. Fossil priapulid worms. Special Papers in Palaeontology, 20: 1-95.

HARVEY, T. H. P., X. DONG AND P. C. J. DONOGHUE. 2010. Are palaeoscolecids ancestral ecdysozoans? Evolution & Development, 12(2): 177-200.

WALCOTT, C. 1911. Cambrian Geology and Paleontology II. Middle Cambrian annelids. Smithsonian Miscellaneous Collections, 57(5): 109-145.

WALCOTT, C. 1931. Addenda to descriptions of Burgess Shale fossils. Smithsonian Miscellaneous Collections, 85(3): 1-46.

WILLS, M. A. 1998. Cambrian and Recent disparity: the picture from priapulids. Paleobiology, 24(2): 177-199.

Other links:

None

Back to top