Selkirkia

For the plant genus, see Selkirkia (plant).

Selkirkia is a genus of predatory,^[3] tubicolous priapulid worms known from the Middle Cambrian Burgess Shale, Ogygopsis Shale, Puncoviscana Formation^[4] and the Early Ordovician Fezouata Formation.^[5] 142 specimens of Selkirkia are known from the Greater Phyllopod bed, where they comprise 0.27% of the community.^[6] 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 trilobites).^[3] Whilst alive, the tubes were probably vertical, whereas trilobite-occupied tubes are horizontal.^[3]

Selkirkia Temporal range: Cambrian Stage 3–Floian PreꞒ Ꞓ O S D C P T J K Pg N
Selkirkia columbia fossil from the Burgess Shale. From Smith et al. (2015)[1]
Restoration of Selkirkia columbia
Scientific classification
Kingdom:	Animalia
Stem group:	Priapulida (?)
Class:	†Archaeopriapulida
Family:	†Selkirkiidae Conway Morris, 1977[2]
Genus:	†Selkirkia Walcott, 1911
Species
S. columbia Conway Morris, 1977 S. elongata Luo & Hu, 1999 S. sinica Luo & Hu, 1999 S. spencei Resser, 1939 S. willoughbyi Conway Morris & Robison, 1986 S. tsering Nanglu 2024

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 were originally described as Selkirkia before their identification as a separate genus.^[7]