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Usually, soft-bodied species like spiders aren't fossilized in rock like animals with bones and teeth. More often, ancient spiders and insects are more likely to be discovered preserved in amber.
Yet a new paper in the Journal of Systematic Palaeontology, co-written by a University of Kansas researcher, describes fossil spiders found in an area of Korean shale called the Lower Cretaceous Jinju Formation.
Fossils - Spider - Family - Lagonomegopidae - Feature
What's most remarkable: Two of the fossils from the extinct spider family Lagonomegopidae feature reflective eyes that enabled their nighttime hunting.
"Because these spiders were preserved in strange slivery flecks on dark rock, what was immediately obvious was their rather large eyes brightly marked with crescentic features," said Paul Selden, Gulf-Hedberg Distinguished Professor of Geology and director of the Paleontological Institute at KU's Biodiversity Institute and Natural History Museum. "I realized this must have been the tapetum—that's a reflective structure in an inverted eye where light comes in and is reverted back into retina cells. This is unlike a straightforward eye where light goes through and doesn't have a reflective characteristic."
Selden - Spiders - Eyes - Tapetum - Paper
Selden said that some contemporary spiders feature eyes with a tapetum, but the new paper is the first to describe the anatomical feature in a fossilized spider. The research team said the discovery provides evidence for lagonomegopid enlarged eyes being posterior medians.
"ln spiders, the ones you see with really big eyes are jumping spiders, but their eyes are regular eyes—whereas wolf spiders at nighttime, you see their eyes reflected in light like cats," he said. "So, night-hunting predators tend to use this different kind of eye. This was the first time a tapetum had been in found in fossil. This tapetum was canoe-shaped—it looks a bit like a Canadian canoe. That will help us place this group of spiders among other families."
Selden - Collaborators - Tae-Yoon - Park - Korea
Selden's collaborators were Tae-Yoon Park of the Korea Polar...
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