Scary ancient spiders revealed in 3-D models, thanks to new imaging...( Early relatives of spiders that liv...)

Early relatives of spiders that lived around 300 million years ago are revealed in new three-dimensional models, in research published today in the journal Biology Letters.

Scientists at Imperial College London have created detailed 3D computer models of two fossilised specimens of ancient creatures called Cryptomartus hindi and Eophrynus prestvicii, closely related to modern-day spiders. The study reveals some of the physical traits that helped them to hunt for prey and evade predators.

The researchers created their images by using a CT scanning device, which enabled them to take 3,000 x-rays of each fossil. These x-rays were then compiled into precise 3D models, using custom-designed software.

Both Cryptomartus hindi and Eophrynus prestivicii were around the size of a 50 pence piece and they roamed the Earth during the Carboniferous period, 359 299 million years ago. This was a time before the dinosaurs, when life was emerging from the oceans to live on land. During this period, the world's continents were merging together near the equator to form one supercontinent and the first tropical rainforests were playing host to a diverse range of species.

Previous studies of the fossilised remains of Cryptomartus hindi allowed scientists to see some features of the creature, which had four pairs of legs and looked similar to a spider.

In the new study, the researchers' computer models reveal that Cryptomartus hindi's first two legs were angled towards the front of the body, which suggests that it used its legs to grab its prey before killing them. The researchers believe this find suggests the Cryptomartus hindi was an ambush predator, living in logs and fronds, waiting for prey such as insects to walk by before catching and killing them. This stance is seen in modern day crab spiders, which sit on the edge of flowers and wait for insects to land so that they can grab them.