it was a piece of petrified skullbone , representing but a small portion of the head to which it had belonged , but yet sufficient to enable the anthropologists , who immediately fell to examining it , to draw ideal representations of the head as it must have been in lifethe head of a giant of enormous size , which , if it had possessed a highly organized brain , of proportionate magnitude , must have given to its possessor intellectual powers immensely greater than any of the descendants of adam have ever been endowed with .