ADVANTAGES

The Kellwasser event ended the first invasion of land by vertebrates and created an evolutionary bottleneck. Some stragglers survived the Kellwasser event, but the fossil record for the next seven million years has been devoid of tetrapod fossils with the exception of . After the Fammenian Gap ended about 368 mya, tetrapods renewed their invasion of land, and those tetrapods with appeared in the fossil record during the second invasion. was in those days. The tetrapods of the time may have not yet been true amphibians, but they were making the adjustments needed to become true land animals, such as losing their gills and improving their locomotion. No new arthropods appeared on land during that time.

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