Are Pleistocene mammoths and giant bison found in glacier ice and if so what is their age?

To date, the organic remains of Pleistocene mammals have not been found in a glacier. However, the remains of these prehistoric animals are often found in bog sediment, gravel deposits, and ice lenses in frozen soil in permafrost rich Arctic and sub-Arctic areas. Fossils found in permafrost-rich soils may be many tens of thousands of years old.