There are apparently multiple occasions when preserved mammoth flesh from the ice age was eaten: https://www.mentalfloss.com/article/57100/time-250000-year-o...

When in 1901 Soviet researchers discovered woolly mammoth on the banks of Berezovka River in Siberia, they could smell its carcass and supposedly scavengers had been feeding on thousands of years old meat![1]

[1]https://youtu.be/fr0Ifw8TJVw