Dresbachian

The Dresbachian is a Maentwrogian regional stage of North America, lasting from 501 to 497 million years ago.

It overlaps with the ICS-stages Guzhangian, Paibian and the lowest Jiangshanian.

[citation needed] The Dresbachian overlies the Middle Cambrian Albertan series, and is the lowest stage of the Upper Cambrian Croixian series, followed by the Franconian stage.

The term is derived from the town of Dresbach which is located in southeastern Minnesota on the Mississippi River.

They are poorly documented due to a paucity of fossil evidence so early in the evolution of life.

Intensity of Dresbachian extinction event (right side of graph)