Fig. 3. Summary of the most common trilobite moult configurations preserved in the fossil record, illustrated by Redlichia (AeF, usually moulted via the facial sutures and librigenae) and Placoparia (GeL, usually moulted via disarticulation of the entire cephalon). Exoskeleton sections disarticulated during the moulting process shaded grey. A: Complete labelled dorsal exoskeleton of Redlichia. B: Facial sutures opened and librigenae displaced outwards. C: Facial sutures opened and librigenae missing. D: Facial sutures opened and librigenae horizontally flipped (possible if the individual arched during exuviation). E: Facial sutures and cephalothoracic joint opened, causing disarticulation of the librigenae and cranidium. F: As in E, but librigenae missing. G: Complete labelled dorsal exoskeleton of Placoparia. H: Cephalon disarticulated, leaving exuvial gape between cephalon and thorax. I:Cephalon disarticulated and flipped horizontally (Salter's configuration). J: Cephalon and pygidium disarticulated. K: Disarticulation along the thorax (unspecific location). L:Cephalon, thorax and pygidium disarticulated in the same exuvia. Other combinations of these moult configurations can be found preserved in the fossil record, for example disarticulation of the thorax with release of the librigenae. Abbreviations: Ce, cephalon; Ey, eye; Fi, fixigena (fixed cheek); Fs, facial suture; Gl, glabella; Li, librigena (free cheek);