ancient arachnid
July 9, 2014

Ancient Arachnid Lives Again Thanks To New Video Simulation

Gerard LeBlond for - Your Universe Online

One of the first predators to walk on Earth was a 410 million-year-old arachnid, an ancient relative to modern day spiders. Based on its fossils, a video was produced that recreates its locomotion.

The fossils came from the Natural History Museum in London. Researchers from the University of Manchester and the Museum fur Naturkunde, Berlin, used these fossils to create a simulation of how the arachnid presumably walked. The study is published in a special issue of the Journal of Paleontology.

The arachnid was known as a trigonotarbid. It most likely preyed on flightless insects where it would hunt down and then pounce on its victim.

"We know quite a bit about how it lived. We can see from its mouth parts that it pre-orally digested its prey - something that most arachnids do - because it has a special filtering plate in its mouth. So, that makes us fairly sure it vomited digestive enzymes on to its prey and then sucked up liquid food," lead author Dr. Russell Garwood, a paleontologist in the University of Manchester's School of Earth, Atmospheric and Environmental Sciences, told BBC News.

To create the video, scientist used the arachnid’s cross-section fossils from thin slices of rock to produce a range of motion. The team then compared it to the way living spiders move and implemented the data into Blender, an open source computer program to create the video.

"We could see the articulation points in the legs. Between each part of the leg, there are darker pieces where they join, and that allowed us to work out the range of movement. We then compared that with the gaits of modern spiders, which are probably a good analogy because they have similar leg proportions. The software enabled us to see the center of mass and find a gait that worked. If it's too far back compared to the legs, the posterior drags on the ground. The trigonotarbid is an alternating tetrapod, meaning there are four feet on the ground at any one time," explained Dr Garwood.

"When it comes to early life on land, long before our ancestors came out of the sea, these early arachnids were top dog of the food chain. They are now extinct, but from about 300 to 400 million years ago, seem to have been more widespread than spiders. Now we can use the tools of computer graphics to better understand and recreate how they might have moved – all from thin slivers of rock, showing the joints in their legs," Garwood added.

"These fossils – from a rock called the Rhynie chert – are unusually well-preserved. During my PhD I could build up a pretty good idea of their appearance in life. This new study has gone further and shows us how they probably walked. For me, what's really exciting here is that scientists themselves can make these animations now, without needing the technical wizardry – and immense costs – of a Jurassic Park-style film.

When I started working on fossil arachnids we were happy if we could manage a sketch of what they used to look like; now we can view them running across our computer screens," co-author Jason Dunlop, a curator at the Museum für Naturkunde, Berlin, said.