It lasted from 419.62 ± 1.36 to 393.47 ± 0.99 and began with the Lochkovian Stage 419.62 ± 1.36 to 413.02 ± 0.99, which was followed by the Pragian from 413.02 ± 1.36 to 410.62 ± 0.99 and then by the Emsian, which lasted until the Middle Devonian began, 393.47± 0.99 million years ago.

[7] During this time, the first ammonoids appeared, descending from bactritoid nautiloids.

Ammonoids during this time period were simple and differed little from their nautiloid counterparts.

This class of cephalopod molluscs would dominate the marine fauna until the beginning of the Mesozoic Era.

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