Two middle Cambrian diceratocephalid trilobites, Cyclolorenzella convexa and Diceratocephalus cornutus, from Korea: development and functional morphology

Park, T.-Y. & Choi, D.K. 2010: Two middle Cambrian diceratocephalid trilobites, Cyclolorenzella convexa and Diceratocephalus cornutus , from Korea: development and functional morphology. Lethaia , Vol. 43, pp. 73–87.
Silicified sclerites of the latest middle Cambrian trilobites, Cyclolorenzella convexa and Diceratocephalus cornutus , have been recovered from the Sesong Formation, Korea. Their morphological similarity and stratigraphic occurrences suggest that D. cornutus is a descendant of C. convexa . The ontogenies of both trilobites demonstrate that a pair of long frontal horns in the cephalon of D. cornutus is an evolutionarily novel structure. It is inferred that redeployment of some pre-existing regulatory gene played a significant role in constructing the frontal horns of D. cornutus . The frontal horns may have been a defensive structure to deter predators. The facial suture of D. cornutus , which extends onto the frontal horns and splits them into the dorsal and ventral halves, was a solution to enable easier forward egression during ecdysis. □ Functional morphology, Korea, Middle Cambrian, ontogeny, trilobites .