It seems to me that commenters in this thread keep taking the durability of materials under average conditions as a measure of what traces would be left after m

It seems to me that commenters in this thread keep taking the durability of materials under average conditions as a measure of what traces would be left after millions of years. By the same standards, we shouldn't have a single bone or trace that anything that lived more than a few hundred years ago. However, when there is a very large amounts of specimens, some happen to be preserved in exceptional conditions or undergo transformations which let them survive or leave traces, direct or indirect, for tens or even hundreds of millions of years.