Q: What do you call a fossil that never does any work?
A: A lazy bones!

Explanation: Fossils are parts of a living thing that has been preserved, or left an impression from a very long time ago, perhaps 10,000 years ago or more.  The human skull that was recently found in Minnesota was not called a fossil, maybe because it was only 8,000 years old.  Bones are a very common type of fossil because they last longer than the soft parts of living things. Because fossils come from living things that have been dead for a very long time, they do not do any work.

A lazy bones is a person who is lazy, who doesn’t help, who doesn’t do much of anything.  Imagine someone doing the work alone and saying to the other person, “Don’t be such a lazy bones.  Help me get this done!”

This joke is funny because it plays with the idea of bones and fossils, along with ancient bones being lazy.

Watch here to find out how dinosaur fossils are formed: