How old are these fossils.

[Rocks2]

I believe one is a piece of ancient pottery. And I'm not sure what the others are.

 

[Jason in Enid]

Thats impossible to answer without knowing the fossil ID, and the formation and member unit they come from. Many fossils spanned 10s of millions of years. Some could be from any part of a 200 million year spread. The geology of the host matrix and its associated fossils is what defines a much narrower time frame.

And yes, the first item is a pottery shard and not in any way shape or form, a fossil.

 

[Red-Coat]

The fossils are broken sections of crinoid columnals. Those with columnar 'stalks' are sometimes called 'sea lilies' because of their resemblance to plants, but they're marine animals loosely related to starfish and sea urchins. These types first appear in the fossil record during the Ordovician period around 480 million years ago but they're not extinct today (although they did suffer an extinction event), so could be from that time onwards. The youngest known crinoid fossils are from the Rhaetian (Late Triassic) of Iran and date to a little older than 200 million years. Without more information about where you found them it's not possible to say.

 

[jamest64]

Go get'm Redcoat! I take it you are some kind of a paleo guy? Not too many people can go on a tear about Crinoids!

 

[scilover]

The first piece is definitely from a broken off pottery, but the others look like fossils. But determining the age is difficult. There are two ways thou; (1) the first is relative dating which determine a fossils approximate age by comparing it to similar fossils of known ages. (2) absolute dating by using radiometric dating to measure the decay of isotopes.