|1st Species||Mongolarachne jurassica|
|Time Range||164 mya|
|Name Meaning||Mongolian spider|
|Physical Dimensions||10 centimeter legspan for males; 9 centimeter legspan for females|
Mongolarachne is a mongolarachnid spider (aranean arachnid arthropod) from the Middle Jurassic of China. It was officially named in 2011 by Paul Selden, ChungKun Shih, and Dong Ren. It was the biggest spider to exist during pre-Cenozoic times (the presumed mygalomorph spider Megarachne is now known to be a stylonurine eurypterid), and was thought to be a prehistoric species of golden silk orb-weaver before finally being described as its own genus.
Mongolarachne resembled the modern net-casting spider. It was a spider with a small cephalothorax, a large abdomen, large eyes, two sideways-pointing fangs near its mouth, and 4 pairs of long walking legs. Males had smaller cephalothoraces, smaller, thinner abdomina, and longer legs; females on the other hand, had larger cephalothoraces, bigger, rounder abdomina, and shorter legs. Its body would have been covered in a hard, chitinous exoskeleton.
Mongolarachne was a predator, preying on insects and lizards. Its fangs were used for getting a hold of, injecting digestive enzymes into, and sucking all the tissues out of prey.
Mongolarachne lived very similarly to net-casting spiders, hanging from branches and weaving a net-like web, in comparison to other araneomorph spiders, which sit on a web until prey comes by. Once a small animal would come by, the spider would wrap the net around it and tighten it with more silk; it would then inject a digestive enzyme into its prey item (softening its tissues) before sucking out all its soft tissues. It would always hunt at night, as its eyes would gather light more efficiently in the dark. Being nocturnal meant that the spider would have stayed well-hidden from predators such as Epidexipteryx during the day.