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Today in History: Calaveras County miners uncover disputed Pliocene skull

2/25/2026

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Summary

Story summary

On February 25, 1866, miners in Calaveras County, California, unearthed a human skull, claiming it as evidence of human existence during the Pliocene Epoch. This discovery aimed to support the coexistence of humans with mastodons and mammoths. However, the skull was later exposed as a hoax, despite the eventual confirmation of human coexistence with these species in more recent times.

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Story summary

On February 25, 1866, miners in Calaveras County, California, unearthed a human skull, claiming it as evidence of human existence during the Pliocene Epoch. This discovery aimed to support the coexistence of humans with mastodons and mammoths. However, the skull was later exposed as a hoax, despite the eventual confirmation of human coexistence with these species in more recent times.