Revisiting Lophosteus, a primitive osteichthyan

Gross (1968) recognized one species of Lophosteus, L. superbus, from a single locality, Ohesaare Cliff, Saaremaa, and a single time interval, late Pridoli, Late Silurian. Today, six species are recognized and have a worldwide distribution from early Ludlow to early Pragian. We describe three new species from the type locality, the Canadian Arctic and the Urals. The systematic position of the genus is ambiguous. Lophosteus has been placed with sarcopterygians and with actinopterygians, or basal to both osteichthyan groups and in connection to acanthodians. Similarities to placoderms are superficial. We identify Lophosteus as a taxon close to acanthodians.