Tracking trails and traces

because it records the traces of animal activity. Not all fossils are parts of a creature, like bones or shells. Some, such as dinosaur footprints, or the trails left in the sand by some little worm, are trace fossils. If your daffodil bed somehow amazingly got preserved for million of years and turned into rock, then the cat's diggings would be a trace fossil. They may not tell us much about what the animals looked like, but trace fossils tell us a lot about how they behaved. No, I don't mean whether they were good or bad, but whether they crawled or slithered or burrowed - things like that.

Amazing as it may se< the oldest known animal fossil has something in common with the cat's night-time adventure. This very old fossil is called a trace fossil,

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For thousands of millions of years there were no other life forms on Earth but bugs. Lots and lots of bugs. From the tip of your nose until about your elbow, there were just bugs. Then came the seaweeds that I mentioned before. We've found fossil remains of them. Sometimes we see them as spirals in 2000-million-year-old rocks in America, other times as little rows of beads in rocks 1300 million years old in Western Australia. This is long before any animals showed up.

Then we see the first trails and scrapings made in sand by animals, and somehow amazingly preserved in rock for about 700 million years. They are like a faraway snapshot in time. Unlike your cat, we have no idea what the animal looked like that left its trail in the sands of an ancient sea. It was probably something like a tiny worm. More recent trace fossils left by animals often form complex patterns, like spirals, or form burrows in the sand. This shows us that the animals that made them were changing and becoming more complex over millions of years. This is evolution at work again.

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