A fluid filled synovial cavity is not present between

Frontal and parietal bones are the cranial bones joined by coronal suture. The flat skull bones which fuse end-to-end with the help of dense fibrous connective tissues in the form of sutures form the fibrous joints, which lack synovial cavity and synovial fluid. 

Synovial joints are characterised by the presence of fluid filled synovial cavity. Ball and socket joint (between humerus and pectoral girdle), hinge joint (knee joint), pivot joint (between atlas and axis), gliding joint (between the carpals) and saddle joint (between carpal and metacarpal of thumb) are some examples.