The term "fossil" is typically associated with once-living things that have been turned into rock. But wood, leaves, mosses, and insects from an ancient forest in Maine were found preserved without having been mineralized. A recent study delved into the mystery of how these plant and other remains could still be so fresh.

A Cambrian rock layer is considered to be "Cambrian" because of the particular fossils it contains. But what does it mean when a rock layer designated as "Ordovician" contains distinctly Cambrian fossils? Paleontologists are facing that question after a recent find in North Africa.

According to evolution, dinosaurs lived during an age when birds and non-reptile land creatures were either present in just a few "primitive" forms or not at all. But a recent National Geographic online interview offered a summary of fossil discoveries made in a dinosaur-bearing deposit in Madagascar.

A piece of oxygen-darkened amber was said to hold a particular arachnid, but it wasn't clearly visible. Scientists made a surprising discovery when a computed tomography scan was able to produce a finely detailed three-dimensional image of a hunting spider. But if the amber is actually 49 million years old, as is claimed, why hadn't it completely darkened long ago?

The Green River Formation, a sedimentary feature of Wyoming and northern Colorado, is widely recognized for its high quality fossils of fish and other creatures. It has been dated at 40 million years and older. What are the odds, then, of original soft tissue fossils being found encased in its rock?