Some ancient spiders had four eyes, researchers just discovered in studying a 305-million-year-old fossil of a harvestman.
The researchers say that the discovery adds to the evolutionary story of the group of arthropods, which are found across six continents.
University of Manchester scientists, working with colleagues at the American Museum of Natural History, say the X-ray imaging techniques used in the research enabled them to find features of the unusually well-preserved fossil like never before.
“Although they have eight legs, harvestmen are not spiders; they are more closely related to another arachnid, the scorpion,” Dr Russell Garwood, a palaeontologist in the University of Manchester’s School of Earth, Atmospheric and Environmental Sciences, said in a statement.
“Arachnids can have both median and lateral eyes, but modern harvestmen only possess a single set of median eyes – and no lateral ones. These findings represent a significant leap in our understanding of the evolution of this group.”
The spider fossil was found in eastern France and had both median eyes and lateral eyes on the side of the body.
“Terrestrial arthropods like harvestmen have a sparse fossil record because their exoskeletons don’t preserve well,” said Prashant Sharma, a postdoctoral researcher in the Museum’s Division of Invertebrate Zoology and one of the lead authors on the new study.
“As a result, some fundamental questions in the evolutionary history of these organisms remain unresolved. This exceptional fossil has given us a rare and detailed look at the anatomy of harvestmen that lived hundreds of millions of years ago.”
