Cupulocrinus

These sea lilies were collected from the Bobcaygeon Formation in Ontario, Canada, like the other GRI slab with Cupulocrinus humilis. This formation has produced many fine specimens of crinoids, and may be considered a Lagerstätte, an exceptional graveyard for the quality of fossil preservation (Cole et al., 2018). Crinoids disarticulate quickly after death, therefore specimens like this, with articulated stem, calyx, and arms, can only form with rapid burial by sediment (Brett et al., 1997). It is interesting to note that some of the crinoids in this slab show a preferential long-axis alignment, which could indicate the presence of a current at the time of burial (Thomka et al., 2018).

References:

Brett, C.E., Moffat, H.A., and Taylor, W.L., 1997, Echinoderm taphonomy, taphofacies, and Lagerstätten, in Waters, J.A. and Maples C.G. (eds.) Geobiology of Echinoderms. Paleontological Society Papers, v. 3, p. 147–190. DOI: https://doi.org/10.1017/S1089332600000243.

Cole, S.R., Ausich, W.I., Wright, D.F. and Koniecki, J.M., 2018. An echinoderm Lagerstätte from the Upper Ordovician (Katian), Ontario: taxonomic re-evaluation and description of new dicyclic camerate crinoids. Journal of Paleontology, 92(3), pp.488-505. DOI: https://doi.org/10.1017/jpa.2017.151.

Thomka, J.R., Brett, C.E., Bole, T.A. and Campbell, H.J., 2018. A noteworthy accumulation of disparid crinoids from the type Cincinnatian (Upper Ordovician) of southwestern Ohio, USA: implications for the palaeoecology and taphonomy of crinoid “logjam” assemblages. Swiss Journal of Palaeontology, 137, pp.259-264. DOI:10.1007/s13358-018-0159-8.