About 400 million years ago, giant swimming sea scorpions dominated the Ordovician, Silurian, and Devonian seas! In this video, I go over what exactly these sea scorpions were (spoiler alert, they aren't actually directly related to true modern scorpions), when they lived, their size range (which was quite impressive, ranging from a few cm to over 2.5 m or 8 ft!), their role in ecosystems as both prey and predator, their decline and ultimate extinction, which was largely driven by the evolution and diversification of jawed fish, like placoderms and sharks, in the Devonian and onward throughout the Paleozoic Era, and their lasting impact on marine ecosystems, even after they went extinct!

0:00 What are sea scorpions?
2:26 Impressive size range!
3:48 Evolution through time
4:41 Why so successful?
8:11 From predator to prey
11:49 Why jawed fish took over
13:42 Their decline & extinction
15:00 Sea scorpion’s lasting impact
16:12 Arthropod success on Earth today!

References:
Earth System History: https://amzn.to/3v1Iy0G

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Brief history of Earth by A. Knoll: https://amzn.to/3w3hC1I
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