Chelicerate head structures differ considerably from those of mandibulates ( i . e . insects, crustaceans and myriapods ); they possess eyes and a single pair of grasping appendages innervated from the brain, plus a labrum-like structure.
12.
Early insect herbivores were mandibulate and bit or chewed vegetation; but the evolution of vascular plants lead to the co-evolution of other forms of herbivory, such as sap-sucking, leaf mining, gall forming and nectar-feeding.
13.
Open reduction with direct skeletal fixation allows the bones to be directly mandibulated through an incision so that the fractured ends meet, then they can be secured together either rigidly ( with screws or plates and screws ) or non-rigidly ( with transosseous wires ).
