Cephalic biomechanics underpins the evolutionary success of trilobites

Arthropods (i.e. insects, spiders, crustaceans, myriapods and others), are the most successful Phanerozoic animals. The group is characterized by possession of a segmented body, jointed limbs hard cuticle that episodically moulted. One highly but now extinct arthropods trilobites. Trilobites underwent episodic moulting (ecdysis), trilobites possess facial sutures, lines weakness in cephalon, via which exuviae shed animal emerges. However, zones appear to represent structural trade-off or constraint, particularly during burrowing; sacrificing consolidated head region useful burrowing for ability moult. Here we reconcile this using biomechanical modelling demonstrate sutures exist regions low stress application loads. Furthermore, structure cephalon enable sutured withstand greater stresses than their non-suture counterparts. We suggest loads enabled successfully invade bioturbated more sediments Cambrian Sediment Revolution, thus facilitating diversification Ordovician contributing evolutionary success iconic arthropod group.