Article: Ontogeny of the Upper Cambrian trilobite Leptoplastus crassicornis (Westergaard) from Sweden

The development of the dorsal exoskeleton of the trilobite Leptoplastus crassicornis (Westergaard) is described from the Upper Cambrian of Andrarum, Scania, Sweden. The cranidium is represented by all stages from protaspis to holaspis, although specimens other than protaspids are disarticulated and precise degrees are unknown; they have therefore been allocated to seven morphological groups. The development of the meraspid librigena, hypostome, and pygidium is also briefly described. The growth of the cranidium is closest to Peltura scarabeoides but also shows similarities with Olenus gibbosus and Leptoplastides salteri. The nature and course of early facial sutures is discussed. Scatter diagrams show growth to be linear and allometric.