A fossil of a large male prehistoric spider has been recently found in the Daohugou beds of Inner Mongolia.  The spider’s species has stumped scientists, who have now proposed a new genus for the discovery called Mongolarachne.

The male prehistoric spider fossil that was found in the Daohugou beds of Inner Mongolia.

This recent discovery comes after the previous unearthing of a female spider fossil in the same area back in 2011. The 165-million-year- old female spider is thought to have belonged to the Nephila species due to its size being close to the modern day Nephilidae (orb-weaver spiders), and was so called Nephila jurassica. But this newly discovered male spider fossil throws a spanner in the works.

While the male spider does resembles the Nephila jurassica, its shape and size has suggested it belonged to another genus. One factor that called for a new genus was its sex appendages, as they did not match those found on modern day Nephila males. Also the male has ‘spirals of hairlets’ that are more feathery than those on modern day orb-weavers.

While the male spider (left) does resembles the Nephila jurassica (right), its shape and size has suggested it belonged to another genus.

These differences have led to Professor Paul Selden from Kansas University, who was part of the teams that discovered both fossils, and other scientists to propose the new genus Mongolarachne from the family Mongolarachnidae. According to Selden’s (2013) paper, these Mongolarachne closely resemble the modern day ogre-faced spiders that belong to the Deinopidae family.

Spider fossils are considered rare because of the soft composure of their bodies, but these two fossils were found within volcanic deposits. It is believed these deposits buried this pair at the bottom of a lake, therefore preserving them in very good condition.

References:

Selden, P.A., Shih, C., Ren, D. 2013. A giant spider from the Jurassic of China reveals greater diversity of the orbicularian stem group. Naturwissenschaften, 100:12. Pg 1171-1181.

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