''Fieldia'' (named after American businessman and financier Cyrus W. Field) is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of worms 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 fo ...

, and assigned to the

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 ...

s. It was originally interpreted as an arthropod; its trunk bears a dense covering of spines, and its proboscis is small. It fed on sea-floor mud, evidenced by the frequent presence of sediments preserved in its gut. It reached 5 cm in length. Along with the other Cambrian priapulids ''

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'', ''

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 ...

'', '' Ancalagon'', '' Scolecofurca'', and '' Lecythioscopa'', the organism was originally classified into a clade termed the

Archaeopriapulida Archaeopriapulida is a group of priapulid-like worms known from Cambrian lagerstätte. The group is closely related to, and very similar to, the modern Priapulids. It is unclear whether it is mono- or polyphyletic. Despite a remarkable morpho ...

, 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, and their similarity to the modern genus '' Maccabeus'' suggests that they are in the Seticoronaria stem group, and thus are true crown-group priapulids. A phylogenetic analysis does not provide a great deal of resolution to the relationships between these basal worms. 18 species of ''Fieldia'' 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 0.03% of the community.

References

External links

* {{Taxonbar, from=Q5447162 Burgess Shale fossils Burgess Shale animals Prehistoric protostome genera Cambrian genus extinctions