Earliest fossil spiders

The earliest fossil spiders existed approximately 300 million years ago, during the Carboniferous era, their fossilised remains having been preserved in the coal measures of North America and Europe. They probably belonged to a suborder of primitive spiders known as Mesothelae, which are represented today by a single living taxonomic family, and bore their spinnerets underneath the middle of their opisthosoma (the abdominal section in spiders), rather than underneath its rear end, as occurs in more advanced, modern spiders. Certain of these early spiders, belonging to the extinct taxonomic family Arthromygalidae, looked somewhat like tarantulas, even though they were only very distantly related to them.

These earliest spiders are likely to have been ground-dwelling predators, inhabiting the giant club moss and fern forests prevalent in those ancient times, and they probably preyed upon other primitive arthropods. They may have used their silk merely as a protective covering for their eggs, or as a lining for a retreat hole, and later perhaps for simple ground sheet web and trapdoor construction, before its most famous modern-use, for weaving webs, eventually arose.