Madeiran Cylichnidia Snail (Cylichnidia cylichna)  

This species was endemic to the island of Madeira, it is known from fossil and subfossil shells both from Middle Pleistocene to Holocene deposits, the youngest shells can be dated to an age of only about 50 years, it thus disappeared, completely unnoticed, sometimes during the 1950s. [1]

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References:

[1] Glenn A. Goodfriend; R. A. D. Cameron; L. M. Cook: Fossil evidence of recent human impact on the land snail fauna of Madeira. Journal of Biogeography 21: 309-320. 1994

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edited: 16.06.2020