Fossilized polyps in 430-Myr-old Favosites corals

Abstract

Tabulate corals are among the more characteristic fossils of the Silurian period, but because only their skeletons have been preserved, their taxonomic position and mode of life have been uncertain. Although they are generally placed¹ in the phylum Coelenterata (Cnidaria), the recent discovery of living sclero-sponges that share architectural affinity with some tabulates, has renewed debate about the evolutionary relationships of the latter. In particular, the tabulates have been assigned^2,3 to the sponges (phylum Porifera). I report here the discovery of fossilized polyps in a Favosites from the Silurian of Quebec. This incontravertibly demonstrates that the tabulates belong to the phylum Cnidaria, and details of the soft-part morphology suggest that the Tabulata form a group distinct from other corals.