Question

Difference between altered and unaltered fossils.

Answer 1

In unaltered fossils, the original material is still composed
eg:preserved permafrost ed mammoth fossils
In altered fossils , the original material is replaced by another substance
eg: agatized dinosaur bones

Answer 2

An unaltered fossil still is composed of the original material - like the mammoths preserved in permafrost. An altered fossil has had the orginial material replaced by another substance; an example is the dinosaur bones that are now agatized.