Soft, squishy, ancient spiders are hard to investigate – they do not fossilise as easily as bones or exoskeletons. So you can imagine how excited researchers were to find 10 brand new spider fossils in a relatively unexplored area called Jinju Formation
The Jinju Formation is a geological area of South Korea from the Mesozoic era between 252 and 66 million years ago. This new spate of fossils, which researchers from the Korea Polar Research Institute and the University of Kansas found in shale, has increased the number of known spiders in Jinju Formation from just one to a whopping 11.
But two of these spiders Findings were even more exciting than the rest – their eyes still reflected light 1
"Because these spiders were preserved in strange slivery flecks on dark rock, what was immediately evident was their rather large eyes brightly marked with crescentic features, "said Paul Selden, geologist at The University of Kansas.
" I've realised this must have been the tapetum – that's a reflective structure in an inverted eye where light comes in and is reverted back into retinal cells. " This structure aids night vision. Human eyes do not have a tapetum, but many animals do;
The researchers believe that this is the first preservation of a spider eye in all fossil record
"In spiders, the ones you see with really big eyes are jumping spiders, but their eyes are regular eyes – while wolf spiders at nighttime, you see their eyes reflected in light like cats," explained Selden. So, night-hunting predators tend to use this different kind of eye.This was the first time a tapetum had been found in fossil. "
" It's nice to have an exceptionally well-preserved feature of anatomy like eye structure. It's really not often you get something like that preserved in a fossil. "
Most ancient spiders are discovered in amber because they help preserve the soft bodies of the arachnids.
However, the researchers believe that if these spiders are named Koreamegops samsiki and Jinjumegops dalingwateri – had been found in amber, the tapetum might have been missed
"They do not have hard shells so they can easily decay," Selden said. "These rocks", "The rocks", "The rocks", "The rocks", "The rocks" and they are covered in little crustaceans and fish, so there may have been some catastrophic events like an algal bloom that trapped them in a mucus mat and they sunk them – but that's a conjecture. "
The researchers think that these newly discovered spiders would have been occupying the same niche as the jumping spider does today
"But these spiders were doing things differently. Their eye structure is different from jumping spiders, "Selden explained.
Finding 10 new spiders is a huge win for the diversity of spiders from the Cretaceous period – because of the lack of fossils we just do not know what much about these old creepy crawlies