Casual observers are not the only ones who puzzle over dinosaur footprint origins. After all, other animal tracks in mud are not fossilized today because erosive processes rapidly erase them. If a rock layer requires thousands of years to solidify, then how were dinosaur tracks recorded in them?

A portion of a fossilized dinosaur upper arm bone from Tanzania, originally collected in the 1930s, spent many years nestled among thousands of dinosaur specimens housed at London's Natural History Museum. Re-examined, researchers now claim that it is the oldest dinosaur—or almost a dinosaur—in the world.

Well, was it a dinosaur or not?

Original dinosaur tissues in fossil bones are probably the most controversial finds in all of paleontology. Secular scientists have difficulty interpreting them. They debate whether the tissues are real, based on laboratory-measured tissue decay rates, or whether the tissue decay rates are real, based on plainly observed tissues.

Scientists in China recently discovered that a supposedly simple, ancient creature had an unexpectedly complicated nervous system. The creature was an extinct arthropod found in Cambrian rocks, and it had remarkably preserved nervous tissues that showed it had a three-lobed brain connected to fully developed eyestalks.

DNA is a biochemical that contains genetic information. And like all other cellular ingredients, it decays if cellular systems don't maintain it. Now, scientists are more confident about how fast it falls apart after a cell dies.