If a fossil has survived 100 million years to be fond one day. How could it possibly still be in tact?

Question

What I'm thinking is no fossil could possibly survive that long. With rates of erosion, volcanoes, earthquakes shaking them violently hundreds, maybe thousands of times over that time period no fossil could survive that long. Maybe I'm wrong but how could anything that long ago even a fossil stay in tact until now.

Answer 1

As was already pointed out, fossil have become rock, and so are not going to decay. The problem is that at the rate the continents are eroding, they would be washed into the ocean in just 10 million years. So if the fossils are really that old, they should be long gone, and the continents with them. Geologists don't have an answer for this problem so they just ignore it. The logical answer is that the continents are simply not that old, but logic seems to have little to do with the age of the earth.

Answer 2

The answer is that most don't survive. We only find the lucky ones that have survived.

If bones survived from every animal that ever lived, the upper layers of the Earth's crust would be full of them.

Note how the broken down shells of quadrillions of ancient sea creatures form massive mountains of limestone and those fantastic chalk cliffs. That gives you some idea of the amount of animals that have lived and died over the aeons.

Fossils only form in extremely lucky circumstances, and fossils of larger animals are not found intact in any case.

Answer 3

A 100 million year old fossil would be mid-Cretaceous, and not at all rare in the fossil world. Fossils are usually hard animal parts like bones and calcareous shells, or imprints of plant structures, that have been replaced by calcite or silica to help preserve them. The soft tissue parts of animals (muscle, skin, and hair) are extremely rare. If a sedimentary rock can be preserved that long without excessive metamorphism and deformation, then the fossil would be preserved as well as its enclosing rocks.

Of course, if the sedimentary rock containing a fossil was subjected to deformation (faulting and folding) and metamorphism (heat and pressure), then it is unlikely the fossil would be preserved. That's what makes fossils rare - you won't find them in igneous rocks or metamorphic rocks!

Answer 4

Most fossils are solid rock (all the organic material that was originally in the creature's remains have been replaced by minerals over the ages). A rock lasts a long time.

Answer 5

Stromatolite fossils have been found dating back approximately 3.5 billion years ago. They have been preserved in rock layers in the pilbara regions of Western Australia.