A New Conulariid (Cnidaria, Scyphozoa) From the Terminal Ediacaran of Brazil

Paraconularia ediacara n. sp., the oldest documented conulariid cnidarian, is described based on a compressed thin specimen from terminal Ediacaran Tamengo Formation near Corumbá, Mato Grosso do Sul State, Brazil. The was collected laminated silty shale bed also containing Corumbella werneri and vendotaenid algae. consists of four partial faces, two which are mostly covered, one exposed corner sulcus. faces exhibit 32 bell-curve-shaped, nodose transverse ribs, with some nodes preserving short, adaperturally directed interspace ridge (spine). ribs bend adapertureward shoulders sulcus, within terminate, end portions face alternating slightly overlapping those adjoining face. This first body fossil showing compelling evidence homology particular genus. However, unlike periderm Phanerozoic conulariids, P . lacks calcium phosphate, difference may be original or an artifact diagenesis weathering. discovery in corroborates hypothesis, part molecular clock studies, that cnidarians originated during mid-late Proterozoic times, serves as new internal calibration point, dating split between scyphozoan cubozoan at no later than 542 Ma. Furthermore, P. reinforces argument final phase biotic evolution featured advent large-bodied eumetazoans, including, possibly, predators.