An Invertebrate is an animal without a backbone. The group includes 95% of all animal species; all animals except those in the chordate subphylum Vertebrata (fish, amphibians, reptiles, birds, and mammals).
Ammonites first emerge.
Ammonites die out.
Megopteran thrive in the ruins of human civilisation, locked in conflict with their vertebrate enemies the Future Predators. A type of Future Worm that could possibly be larvae of the Megopteran exists in this time as well. (Episode 3.8, Episode 3.10) In another Future, the descendants of Beetles became swarms of ravaging killers and fight for live underground with larger carnivorous arthropods. (Episode 5.1, Episode 5.4)
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