''Selkirkia'' is a genus of predatory, tubicolous

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 ...

worms known from the Middle

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

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 fos ...

, Ogygopsis Shale,

Puncoviscana Formation Puncoviscana Formation () is a formation (geology), formation of sedimentary rock, sedimentary and metamorphic rock, metasedimentary rocks Ediacaran, Late Ediacaran and Cambrian, Lower Cambrian age, estimated at between 700 and 535 Ma, that crop o ...

and the Early

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...

Fezouata Formation The Fezouata Formation or Fezouata Shale is a geological formation in Morocco which dates to the Ordovician, Early Ordovician.

. 142 specimens of ''Selkirkia'' 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 ...

, where they comprise 0.27% of the community. In the Burgess Shale, 20% of the tapering, organic-walled tubes are preserved with the worm inside them, whereas the other 80% are empty (or sometimes occupied by one or more small

agnostid Agnostidae is a family of Agnostida trilobites. Like all Agnostina, they were eyeless and had only two thoracic segments. These trilobites inhabited benthic waters worldwide from 508 to 461 million years ago. The family includes the following gene ...

trilobites). Whilst alive, the tubes were probably vertical, whereas trilobite-occupied tubes are horizontal.

Morphology

''Selkirkia'' had a body divisible into a proboscis towards the anterior of a trunk enclosed by a tube. The proboscis would have been partially invertable and was armed with several spinules and spines, decreasing size distally overall. It was controlled by at least two sets of anterior retractor muscles. Immediately behind the proboscis was the trunk, smooth for the most part but lined with papillae towards the anterior. Surrounding the trunk was the tube, which way very finely annulated (4 annulations per 0.1 millimeters).

History

Members of ''

Cambrorhytium ''Cambrorhytium'' is an enigmatic fossil genus known from the Latham Shale (California), and the Chengjiang (China) and Burgess Shale (Canadian rockies) lagerstätte. 350 specimens of ''Cambrorhytium'' are known from the Greater Phyllopod bed, w ...

'' were originally described as ''Selkirkia'' before their identification as a separate genus.See ''

''.

References

External links

* Burgess Shale fossils Prehistoric protostome genera Priapulida Wheeler Shale Ordovician genus extinctions Fossil taxa described in 1911 {{cambrian-animal-stub