Development of the early Cambrian oryctocephalid trilobite <i>Oryctocarella duyunensis</i> from western Hunan, China

Abstract Abundant articulated specimens of the oryctocarine trilobite Oryctocarella duyunensis from lower Cambrian (Stage 4, Series 2) Balang Formation at Bulin section in western Hunan Province, South China, permit description all meraspid degrees. The maximum number thoracic segments observed this collection is 11. Meraspid growth was accompanied by progressive and gradual change overall form, animal showed an homonymously segmented trunk with variation pygidial during ontogeny. Such permits a variety plausible explanations, but model successive instars defined segments, suborder highly unlikely to explain pattern because it would result loss between some instars. Degree-based ontogenetic staging compatible observed.