Ancient Daddy Longlegs Had Four Eyes, Not Two
Ancient harvestmen arachnids, commonly known as "daddy longlegs," had not one but two sets of eyes, new research shows.
X-Rays taken of the 305-million-year-old harvestman fossil revealed that the ancestors of these spider-like creatures had two sets of eyes.
The discovery, which was made by the University of Manchester and the American Museum of Natural History, differentiates the creature from other species of arachnid after revealing the creature evolved into having a single pair of eyes.
The fossil, named Hastocularis argus, was found in eastern France. Prashant Sharma, a postdoctoral researcher at the Museum of Natural History told Eureka Science News that fossils like that of the harvestmen were a rare discovery because they did not preserve well.
"Terrestrial arthropods like harvestmen have a sparse fossil record because their exoskeletons don't preserve well."
"As a result, some fundamental questions in the evolutionary history of these organisms remain unresolved."
"This exceptional fossils has given us a rare and detailed look at the anatomy of harvestmen that lived hundreds of millions of years ago," he said. "Fossils preserved in three dimenstions are quite rare. This is especially true of harvestmen. Our X-ray techniques have allowed us to reveal this fossil in more detail than we would have dreamed possible two decades ago."
The fossil shows the creature had lateral eyes located either side of its body, as well as median eyes found near the centre of the insect.
The finding adds another layer to the evolutionary history of arthropods, which are found on every continent in the world with the exception of Antarctica.
Researchers from the American Museum of Natural History and the University of Manchester used X-ray imaging techniques to distinguish features of the well-preserved fossil.
According to The Wire, the technique uses microscopic waves to reconstruct tiny body structures that had been invisible to generations of anatomists.
Dr. Russell Garwood, a paleontologist at the University of Manchester, said explained that "Although they have eight legs, harvestmen are not spiders; they are more closely related to another arachnid, the scorpion."
"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."
Harvestmen usually live on the ground in moist areas, such as under rocks and logs. Harvestmen do not produce silk or venom, despite myths that they are among the most venomous creatures on Earth.