[smartasafruit (OP)]

How likely is it that you are in some place in the world and there are no animal bones underneath you? No matter how deep under the earth they are. But I mean actually still more or less intact bones and not oil. Also fossilized bones or remains are OK. As many animals as there are, would such a place have to be impossible, or do I think in wrong scales and there are not so many animals as I think that their are?

[Janus]

How likely is it that you are in some place in the world and there are no animal bones underneath you? No matter how deep under the earth they are. But I mean actually still more or less intact bones and not oil. Also fossilized bones or remains are OK. As many animals as there are, would such a place have to be impossible, or do I think in wrong scales and there are not so many animals as I think that their are?

Bones break up and decompose over time. In a typically humid environment, in a decade or a bit more.  This means most bones decompose before ever being buried very deep.    It is only under unusual conditions that they last longer.  In arid dessert conditions, or if they end up being encased in a way the protects then from the microorganisms that would break them down.  So, in most places in the world, you would be able to dig down and never come across intact bones.

[charles1948]

We have been digging up fossils for nearly 200 years, will the supply run out.

What I'm thinking is, suppose our present civilisation comes to an end. From a new pandemic of more deadly proportions, Or a global nuclear war, or whatever.

Then in say 10,000 years, a new civilisation arises.

 And the new scientists are trying to discover the history of past life on Earth.
Will there enough fossils left for them to work on?

[evan_au]

Then in say 10,000 years, a new civilisation arises.
Will there enough fossils left for them to work on?

Yes.

We mostly look at bones that are exposed on the surface.
- After the current surface is gone, there is more rock under that.
-The ancient Greeks and Romans had tales of the Titans, enormous ancient warriors. More modern research has shown that these tales center on regions with deposits of prehistoric bones, much bigger than human bones.
https://en.wikipedia.org/wiki/Giants_(Greek_mythology)#Location

There are some regions of the world where the rock is so old that it predates bony animals, so these rocks don't have any bones to dig up.
- But the rock itself suggests evidence of life, in that oxygen produced by living organisms turned dissolved iron in the sea into insoluble iron oxide, forming bands in the rock.
See: https://en.wikipedia.org/wiki/Banded_iron_formation

[OokieWonderslug]

Here on the piedmont of NC the only fossils around are jellyfish. They leave a formless blob for a fossil. Most times several blobs. Hard to tell what it is. But no bones. No bones at all.

[charles1948]

Here on the piedmont of NC the only fossils around are jellyfish. They leave a formless blob for a fossil. Most times several blobs. Hard to tell what it is. But no bones. No bones at all.

I'm surprised to hear that jellyfish can leave any fossilised remains at all.  I mean, as you point out, they haven't got any bones.  So what gets fossilised?

[Colin2B]

I'm surprised to hear that jellyfish can leave any fossilised remains at all.  I mean, as you point out, they haven't got any bones.  So what gets fossilised?

Mmmm, it would appear you are capable of asking sensible questions.
It’s not the material of the jellyfish that is preserved, but the imprint they left in very fine sediment.
Jellyfish fossils are rare because they need very special circumstances to occur. The sediment has to be fine and soft enough to take an impression, but firm enough to retain that impression. The site needs to be free of disturbance until the jellyfish has rotted and another layer of fine sediment has been laid down.

[OokieWonderslug]

You can't make out any detail at all. Just shapwless blobs all bunched together. 
in SC I once found a rock that appeared to have brown things in it.  So I took it home and broke one of the brown things out of it and caught a hint of pine smell. So I put it over my lighter and it was definitely pine bark. A pine tree had fallen over and in doing so A lot of pieces of bark fell into the hole made by the tree. And then the mud turned to rock. No way to tell how long ago. Long enough to become hard solid rock.

[charles1948]

I'm surprised to hear that jellyfish can leave any fossilised remains at all.  I mean, as you point out, they haven't got any bones.  So what gets fossilised?

Mmmm, it would appear you are capable of asking sensible questions.
It’s not the material of the jellyfish that is preserved, but the imprint they left in very fine sediment.
Jellyfish fossils are rare because they need very special circumstances to occur. The sediment has to be fine and soft enough to take an impression, but firm enough to retain that impression. The site needs to be free of disturbance until the jellyfish has rotted and another layer of fine sediment has been laid down.

Yes, that sounds reasonable.  But can we be sure, that the fossilised "fine sediments" that you refer to, weren't created by non-biological agents - such as ripples in the sea-water.  Rather than from rotting bodies of jellyfish.

This reminds me of a controversy in the recent past, about Mars.  You know what I mean - when some images of tubular, worm-like structures were discovered in Martian rocks. And claimed to be proof of life on Mars, in the past..

But weren't these claims contested, and largely discredited.  By scientists who made arguments, that the structures were only mineral in origin.   Not fossilised Martian organisms.

Couldn't these same arguments be applied to the supposed fossilised terrestrial jellyfish.  That's to say, they might be mineral, not organic?

[OokieWonderslug]

That is completely possible. There could be other explanations. I've seen beaches with millions of jellyfish on then. And I have seen lakes where they were very thick in the water. So thick that if something killed them around the same time they would become a thin layer of brown formless blobs cemented together. I'd love to hear some other explanations. So what else could reproduce the effect?

[Colin2B]

Yes, that sounds reasonable.  But can we be sure, that the fossilised "fine sediments" that you refer to, weren't created by non-biological agents - such as ripples in the sea-water.  Rather than from rotting bodies of jellyfish.

That’s another reason why these fossils are so rare. There has to be some pretty good evidence in the detail to differentiate between a genuine specimen and a natural formation - which tend to be a simpler shape. 
Experts will be looking for eg tentacles, gonad pattern, possible mouth parts etc