In analyzing the ancient creepy crawler, scientists found that the harvestman didn't have just one set of eyes; they found an extra pair -- a lateral set -- positioned back on the sides of the abdomen.
Modern harvestmen only have one "meridian" set of eyes, towards the front of the body. The fossilized primitive harvestman, or Hastocularis argus, was discovered in eastern France.
"Although they have eight legs, harvestmen are not spiders; they are more closely related to another arachnid, the scorpion,” said lead author Dr. Russell Garwood, a paleontologist at Manchester. "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 researchers' new findings were published in the journal Current Biology.
Filling some of the gaps in the harvestman's evolutionary timeline is difficult, pointed out co-author Prashant Sharma, a postdoctoral researcher at the American Museum of Natural History. "Terrestrial arthropods like harvestmen have a sparse fossil record because their exoskeletons don’t preserve well," he said. "As a result, some fundamental questions in the evolutionary history of these organisms remain unsolved."
[University of Manchester]