Skulls of Homo sapiens were found during an excavation. The skulls were preserved because the bodies were frozen. So, these fossils are _

fossils. The image shows the evolution of skulls. Based on the image, modern human skulls
skulls from 2 to 3 millions years ago.

The fossils are called "frozen fossils" or "cryogenic fossils". Based on the image provided, the modern human skulls are at the far right end of the chart, while the skulls from 2 to 3 million years ago fall within the range of early human ancestors such as Homo habilis and erectus.