Rhombocorniculum is a species of small shelly fossil comprising twisted ornamented cones. It has been described from the Comley Limestone and elsewhere. R. cancellatum straddles the Atdabanian/Botomian boundary.[1] The structure of its inner layer suggests that its phosphatic fibres formed within a flexible organic matrix.[3]
Taxonomy
Three species are recognized — in stratigraphic succession: R. insolutum, R. cancellatum (=R. walliseri), and R. spinosus (=Rushtonites spinosus).[4] Landing (1995) refers R. insolutum to the strictocorniculids, along with Rushtonites.[3] Hinz (1987) considers insolutum to fall within the variability seen in cancellatum.
Affinity
Based on details of the ornament and construction, Rhombocorniculum is interpreted as the spines of a Hallucigenia-like lobopodian worm.[5]
^ abBrasier, M. D. (1986). "The succession of small shelly fossils (especially conoidal microfossils) from English Precambrian–Cambrian boundary beds". Geological Magazine. 123 (3): 237. doi:10.1017/S0016756800034737.
^Otto H. Walliser (1958). "Rhombocorniculum comleyense n. gen., n. sp". Paläontologische Zeitschrift. 32 (3–4): 176–180. doi:10.1007/BF02989029.
^ abLanding, E. (May 1995). "Upper Placentian-Branchian Series of Mainland Nova Scotia (Middle-Upper Lower Cambrian): Faunas, Paleoenvironments, and Stratigraphic Revision". Journal of Paleontology. 69 (3): 475–495. doi:10.1017/S0022336000034879. JSTOR1306322.
^Brasier, M. D. (1989). Towards a biostratigraphy of the earliest skeletal biotas. In J. W. Cowie & M. D. Brasier (Eds.), The Precambrian-Cambrian boundary (pp. 117–165). Oxford: Clarendon Press.