The parietal bone and occipital bone are connected by the lambdoid suture

the occipital, parietal and temporal bones

Wikipedia says: The lambdoid suture (or lambdoidal suture) is a dense, fibrous connective tissue joint on the posterior aspect of the skull that connects the parietal and temporal bones with the occipital bone.
The Lambdiod suture connects the occipital bone to the parietal bones and the mastoid part of the temporal bone.
The lambdoid suture joins the occipital bone to the parietal bones.
occipital and parietal bones
Lambdoid suture(s): separates the parietal bones and the occipital bone; it arches across the back of the skull ending bilateral where the parietal and occipital bones meets the temporal bone.

occipital and parietal bone