Fossils are a source of fascination for many people, and many experts consider spider fossils to be among the most interesting and revealing of all fossil types. Not much is known about the evolution of spiders, which is why nearly every fossilized spider specimen surprises researchers. For example, last year, researchers unearthed a fossil that contained a 100 million year old spider with a tail. This discovery was completely unexpected, as researchers had no idea that a tailed spider ever existed. Now, researchers have discovered ten more spider fossils that contain interesting spider specimens that were previously unknown to researchers. Two of these spiders represent new species, and they possess another trait that has never been seen before in an ancient spider–night vision.

The eyeballs of some animals contain a membrane known as the tapetum which sits directly behind the retina. The tapetum causes an animal’s eyes to appear as if they are glowing when a light is flashed over their eyes in the dark. Most people have probably seen this “glowing” in the eyes of cats. The tapetum allows animals like cats, moths and owls to view the world in night vision during the dark of night. Now, in addition to many other nocturnal animals, the ten fossilized spider specimens also made use of night vision, as their tapeta is still visible if a light is shined over the fossilized specimen’s eyes. According to researchers, it is not often that a fossilized specimen’s visual system is preserved, but when this occurs, researchers can learn much about the nature of the specimen that is fossilized. The manner in which an animal’s eyes are designed can reveal a whole lot about how the animal survived. Most animals that possess tapeta used night vision abilities in order to hunt at night, in other words, these ten spiders were all nocturnal hunters. Although the ten spider specimens encased within the fossils are now extinct, they were quite similar to modern jumping spiders.

Do you know of any other arthropods that possess night vision?