Evolution of spiders

Origin from a chelicerate ancestor and diversification of spiders through geologic time

Spiders have existed for at least 380 million years. The group's origins lie within an arachnid sub-group defined by the presence of book lungs (the tetrapulmonates); the arachnids as a whole evolved from aquatic chelicerate ancestors. More than 45,000 extant species have been described, organised taxonomically in 3,958 genera and 114 families.

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