How they lived
As computer and imaging technologies get evermore powerful, they offer new windows to the past. Russell Garwood began ‘virtual palaeontology’ a few years ago and is now pursuing a PhD in the area, and working on a team at Imperial College London has revealed physical traits of spider-like creatures that lived over 300 million years ago. The team are going through a range of fossils from the Carboniferous period, which is 359-299 million years ago. ‘These fossils,’ explains Garwood, ‘are preserved in something called siderite (iron carbonate), which hasn’t been successfully scanned before. We chose a fairly well known group, these spider-like arachnids, to test the scanning procedure and see how much more information we could get.’ They already knew the basic outline of the creatures that look like spiders, but they wanted to reveal more detail about them which could help indicate something about how they lived, not just their morphology.

Ambush predator
The studies revealed significant findings about the Cryptomartus hindi and the Eophrynus prestivicii. ‘One thing that told us something about how the Cryptomartus lived is that its limbs rotated slightly, and were held out in front of it. It’s a stance seen in modern-day crab spiders, that sit on the side of flowers and grab prey, which is a mode of life called “ambush predation”. If Cyptomartus had the same kind of forelimbs that could grab stuff in front of it, it would suggest that it’s an “ambush predator”, it could live in tree trunks, pounce on prey when it came along, take it back and eat it in relative safety.’

Evolutionary defences
In the Eophyrnus they found a series of defensive spikes going round the back, which in evolutionary terms looked like a defensive adaptation, ‘it would suggest,’ says Garwood, ‘they were there to make it a less energy efficient meal for any predators.’ They aren’t really spiders says Garwood, for one thing they don’t make silk, ‘and they have a segmented posterior. If you find a spider around the house, the posterior half is all fused into a single segment, like a solid mass.’ Some believe they could be related to creatures such as mites whereas others, says Garwood, believe they are related to spiders. The next step is exploring different animal groups from the same time period and getting information on the wider ecosystem.