Paradoxides gracilis was a genus of relatively large trilobites found throughout the world during the Mid Cambrian period. It was a moderately large trilobite (14 cm / 5.5 inches, Paradoxides davidis up to 70 centimetres (28 in)) with a semicircular head, free cheeks each ending with a long, narrow, recurved spine, and relatively large eyes. Its elongated trunk was composed of 20 segments and again was adorned with longish, recurved lateral spines. Its pygidium (caudal shield) was comparatively small and had one or two pairs of long spines on the posterior margin. Paradoxides is a characteristic Middle Cambrian trilobite of the 'Atlantic' (Avalonian) fauna. Avalonian rocks were deposited near a small continent called Avalonia in the Paleozoic Iapetus Ocean. Avalonian beds are now in a narr