Largest Spider Fossil Found in Volcanic Ash

Largest Spider Fossil Found in Volcanic Ash
Fossil female golden orb-weaver spider (Nephila jurassica) from the Middle Jurassic of China.
Credit: Paul Selden.

The biggest known fossil spider has been found in China, a new study says.

According to Paul Selden, the director of the Paleontological Institute at the University of Kansas, he and his team members have discovered the largest spider fossil. The fossil was discovered within ancient volcanic ash located in Inner Mongolia in the Daohugoa fossil beds.

The fossil was about as large as its modern relatives, with a body one inch (2.5 centimeters) wide and legs that reach up to 2.5 inches (6.3 cm) long. Golden orb-weavers nowadays are mainly tropical creatures, so the ancient environment of Nephila jurassica probably was similarly lush.

Published in Biology Letters, Selden and his team say this spider would have lived in a more tropical climate than the one it was discovered in, suggesting the area has undergone great climate change. They believe the spider originated on Pangaea (the supercontinent). The Nephila jurassica, like modern day golden orb-weavers, would have lived within its orb web, probably in the clearing of a forest or close to source of water.

Until this discovery, the oldest known Nephila genus fossil was 34 million years old, making this fossil and the origin of the Nephila spiders much older than originally thought. While it is the largest spider fossil ever found, it is not the oldest. Other spider fossils found have been as old as 310 million years (Eocteniza silvicola and Protoctenzia Britannica), but they were not the Nephila genus.

The spider’s spinnerets, or silk spinning organs, were visible on the fossil spider’s legs, suggesting that it, like its modern day orb-weavers, were capable of spinning large, durable webs capable of trapping a variety of insects. The larger Nephila spiders of today, growing as large as four or five inches, are able to spin webs strong enough to trap small birds and bats.

The above story is based on materials provided by the University of Kansas.
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