GyracanthidesGyracanthides is an extinct genus of acanthodian gnathostome, known from Devonian to Early Carboniferous.DescriptionGyracanthides is large acanthodian, G. murrayi reached the length up to. The pectoral fin spines are large compared to its body, for specimen that have estimated to be had pectoral fin spines around long. A recent study suggested that Gyracanthides is closely related to chondrichthyans, and that acanthodians are paraphyletic.