Image Shows What Scientists Describe As Almost A Spider

The image you see here is a computer tomography picture of an arachnid that is 305 million years old. It might look like a spider, but it isn't quite a spider according to scientists. The ancient arachnid has scientists aflutter because it is believed to show the stepwise evolution of arachnids into spiders. The only thing this fossil lacks that sets it apart from a spider is the spinnerets spiders use to turn silk into webs.

"It's not quite a spider, but it's very close to being one," said study researcher Russell Garwood, a paleontologist at the University of Manchester in the United Kingdom.

The arachnid in the image is called the Idmonarachne brasieri. The name comes from a Greek mythology figure Idmon, the father of Arachne who was a weaver turned into a spider by a jealous goddess. The oldest known spider fossil is also 305 million years old and together the two show that spiders lived alongside each other at the same time.

The new fossil has a segmented abdomen rather than the fused abdomen that modern spiders have. Scientists say that arachnids were among the first land dwellers on the ancient world, but with few rocks from this period, their origins are murky due to lack of fossils to study. This particular fossil was discovered decades ago and measures 0.4-inch long.

It wasn't much help until recently because half the fossil is buried in rock, but it was viewable using computer tomography. That technique allowed the scientists to see inside the rock and study the legs and mouthparts to identify genus and species. "Arachnids as a whole are an incredibly successful group," he said. "They're the most diverse group of living organisms after insects. They're really, really successful — but we have a very limited understanding of how they are related to each other."

SOURCE: LiveScience