Fossils are any sign of ancient life, and they come in many forms. The most familiar are bones, teeth, and shells—the hard parts that form the skeleton of an animal. After being buried in sand or mud, these hard bits are gradually replaced by minerals and turned to rock, leaving a fossil. Sometimes soft things like leaves and bacteria can fossilize as well, often by making impressions in the rock.
The same is sometimes true of the soft parts of animals, like skin, feathers, or even muscles and internal organs.
But to end up with these as fossils, we need to be very lucky: the animal needs to be buried so quickly that these fragile tissues don't have time to decay or get eaten by predators.#6283•
Chapter 2
Salamanders bigger than humans seem like a mad hallucination. As bizarre as they were, though, Metoposaurus and its kin were not aliens. These terrifying predators were the ancestors of today's frogs, toads, newts, and salamanders. Their DNA flows through the veins of the frog hopping around your garden or the one you dissected in high school biology class.
As a matter of fact, many of today's most recognizable animals can be traced back to the Triassic.#6282•