A 500 Million-Year-Old Brain Fossil Sheds Light on the Rise of Heads

A researcher has gathered a piece of evidence that helps shed light on the evolutionary transition from soft-bodied animals with no well-defined heads to hard-bodied animals that sported heads. The clue comes from one of the oldest fossilized brains ever found—a more than 500 million-year-old specimen of the Cambrian arthropod Odaraia alata found in western Canada. The fossil brain shows evidence of a neural connection between a hard plate, called the anterior sclerite, and eye-like structures via nerves that originated in the front part of the brain.

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