Both examples are placed in the mogerica family Mogolarachidae, both preserved as compression fossils in a pale laminated sedimentary tuff created by ashfall from a volcanic eruption.
The 165-million-year-old female Mogolarache holotype has a body length of about 24.6 millimeters, while the forelimbs reach about 56.5 millimeters in length. The specimen was discovered in 2005 in outcrops of the Jiυlogsha Formation exposed in the Wυhυa Trail by farmers in Ier Mogolia. Scientists at the time described the fossil as Nephila jυrassica, a species of orb-weaver spider that spins 1.5-meter webs of strong, golden silk.
illustrating images
More recent studies in 2013 led to the reclassification of the female after the discovery of a male specimen and the determination that the female had orbicular stem traits and was likely a cribellate-type spider.
The allotopean male specimen, discovered in the same location as the female, has a body length of 16.54 millimeters and a first leg stretch of 58.2 millimeters. The male fossil demonstrates a lack of sexual dimorphism between male and female, and sexual appendages that correlate with modern Nephila males.
The largest spider fossil ever discovered
The 2013 study also concluded that Mogolarachidae, compared to Jraraeidae and possible modern relatives, shows that the fossils appear to be related to Deiopidea (also known as the castig spiders), and possibly some Nicodamidae and Αυstrochil. idae. Arachnids in this group are considered to be orbicυlaria. They also make orb-shaped nets, but their silk is more “woolly” with a stickiness that is more like velcro than glue.
To date, specimens of Mogolaraché jυrassica are the largest spider fossils ever discovered.
