First evidence of attached juveniles in the solutan echinoderm Pahvanticystis from the middle Cambrian Weeks Formation (Utah, USA)

Abstract

The fossil record of the Palaeozoic echinoderm class Soluta suggests they originated in the Miaolingian (middle Cambrian) of Laurentia as permanently attached suspension feeders, demonstrating a stepwise shift towards vagility in successive strata. Here, we report a new specimen of Pahvanticystis cf. utahensis associated with three putative juveniles interpreted as belonging to the same species. We interpret this as evidence of facultative attachment in juveniles of Pahvanticystis, which had not previously been reported in this taxon, but is known in the earlier genus Castericystis. Our findings indicate that attachment as a juvenile was more widespread in solutans than previously thought.