The ornamental design for a skull mount assembly, as shown and described.
FIG. 1 is a perspective view of a skull mount assembly shown in an uncoupled condition;
FIG. 2 is a top view of the skull mount assembly of FIG. 1;
FIG. 3 is a bottom view of the skull mount assembly of FIG. 1;
FIG. 4 is a right side view of the skull mount assembly of FIG. 1;
FIG. 5 is a left side view of the skull mount assembly of FIG. 1;
FIG. 6 is a front view of the skull mount assembly of FIG. 1;
FIG. 7 is a back view of the skull mount assembly of FIG. 1; and,
FIG. 8 is a natural perspective view of the coupled two part skull mount assembly of FIG. 1.
The broken line drawings of the images, text, and other elements shown in the figure are shown for illustrative purposes only and form no part of the claimed design. In addition, the surface shading, if any, illustrated in the drawings is provided merely to highlight the contour of the design; it is not intended to be illustrative of texture or gloss.