305 Million Year Old 'Almost Spider' Could Be Missing Link in Spider Evolution

By Ana Verayo / 1459694581
(Photo : University of Manchester) This 305 million year old "almost spider" could be the missing link to arachnid evolution.

Scientists have investigated an odd spider specimen that questions the origins of spiders, hopefully shedding more light to the evolution of arachnids. This preserved fossilized specimen is housed under the collections of Muséum National d'Histoire Naturelle in Paris.

Researchers says that this 305 million year old fossil was first uncovered from the ancient rock formations of Montceau-les-Mines in the eastern region of France by an amateur archaeologist Daniel Sotty during the 1980s. 

This specific ancient arachnid fossil was unable to be examined in the past by scientists since the spider was buried halfway into the rock, where its abdomen is the only part that has been exposed.

However, with the help of modern technology, researchers have utilized high resolution CT (computerized tomography) scans, as researchers were able to get a better view of the buried half of the arachnid, to be able to create a 3D model that reveals different arachnid characteristics and features like modern spiders' fangs. 

After scanning the specimen, researchers were able to measure the arachnid's features which also resemble spiders' mouthparts and legs, where the arachnid's body measured 0.4 inches long. However, one feature that is lacking from this ancient spider was the lack of spinnerets or the silk producing, spinning organ of spiders.

The absence of these spinnerets is suggesting that this prehistoric arachnid does not yet possess the ability to spin spiderwebs like modern ones do, although it can still produce silk in order to cover and protect their burrows or wrap their egg sacs.

Scientists also discovered that the fossilized arachnid possesses an abdomen with segments similar to other species of arachnids from the same period. The only difference is, modern spiders have a fused abdomen not like this. 

According to lead author of the study, Russell Garwood of the University of Manchester, this fossil is apparently the closest specimen that is related to a spider that is not a spider. This ancient arachnid ancestor is known as Idmonarachne brasieri that is named after Idmon, who is the father of Arachne in ancient Greek mythology.

Researchers conclude that the Idmonarachne is a crucial ancestor that links the ancient arachnids to modern day spiders down the evolution line. Garwood adds, arachnids are an entirely very successful group. They are really successful in evolving and surviving, however we still have a limited understanding how they are related to one another.

This new study is published in the journal Proceedings of the Royal Society B.