Cambrorhytium

Cambrorhytium is an enigmatic fossil genus known from the Latham Shale (California),^[2] and the Chengjiang (China) and Burgess Shale (Canadian rockies) lagerstätte.^[3] 350 specimens of Cambrorhytium are known from the Greater Phyllopod bed, where they comprise 0.7% of the community.^[4]

Cambrorhytium Temporal range: Chengjiang - Burgess Shale
Scientific classification
Kingdom:	Animalia
Phylum:	Cnidaria
Order:	†Conulatae
Clade:	†Conulariida
Genus:	†Cambrorhytium (Walcott 1908) Conway Morris and Robison, 1988[1]
Species
C. elongatum C. fragilis Walcott 1911 C. gracilis Chang et al. 2018 C. major Walcott 1908 (type)

Etymology

Its name is from the Latin rhytium, drinking horn.^[1]

Description

The fossil is conical, with iterated linear markings on its walls, parallel to its base. Its wall is thin, and it lacks the keel that is distinctive of hyoliths.^[2]

It has been interpreted as a cnidarian polyp, with the interpretation suggesting that the animal lived in the tube and extended tentacles (of which no trace has been found) from the flat aperture.^[5] This is supported by similarities to Palaeoconotuba.^[6] The other possible, but probably unlikely, affinity is with the hyoliths.^[2]

Its similarity with the Lower Cambrian species Torellelloides giganteum may indicate a close relationship.^[1] Cambrorhytium has also been compared to the fossil Archotuba^[5] and Sphenothallus.^[7]

C. elongatum has been described to contain an alimentary canal in a single Chinese specimen.^[8]

Taxonomy

C. major was originally described as a member of the hyolith genus Orthotheca.^[9]

C. fragilis was originally included by Charles D. Walcott in the genus Selkirkia,^[10][11] – a taxonomy that was retained by later workers^[12][13] until finally questioned^[14] and redescribed^[1] as Cambrorhytium in the eighties.