Final answer:
Heidelbergensis craniums had large brow ridges and a pronounced brow ridge similar to Homo erectus. The cranial capacity of Heidelbergensis specimens was larger on average than that of modern humans.
Step-by-step explanation:
The Heidelbergensis craniums had several distinct characteristics. They had large brow ridges and a robust humerus, indicating well-developed muscles. Their skulls were flattish on top and rounded at the back, with a pronounced brow ridge similar to Homo erectus. The cranial capacity of Heidelbergensis specimens ranged from about 1,200 to 1,650 cubic centimeters, which is larger on average than that of modern humans.