Incredible Fossil Discovery Shows Ancient Animal Brain From 310 Million Years Ago

The discovery of a 310 million-year-old horseshoe crab in the US, complete with its brain intact, adds to a recent string of fossil finds which have unearthed some of the oldest arthropods with a preserved central nervous system. The horseshoe crab fossil we document in the study sheds new light on how these fragile organs – typically prone to very rapid decay – can be preserved with such fidelity.

These fossils preserve an incredible amount of anatomical detail, as well as behaviors, mainly because very little decay takes place after the organism is rapidly trapped in the resin.

Using sophisticated imaging technology on these amber fossils, paleontologists can study tiny arthropod brains in 3D at minuscule scales. However, the oldest arthropods in amber only extend back to the Triassic Period (around 230 million years ago).

Burgess Shale-type deposits are much older, being Cambrian in age (typically 500 to 520 million years old). They contain an abundance of exceptionally preserved marine arthropods.

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