Halloween is only a few months away. Here is an early scare:Â primordial spiders in 3D! (See the videos of two different ancient spiders.)
Early relatives of spiders that lived around 300 million years ago are revealed in new three-dimensional models, in research published today in the journal Biology Letters.
Scientists at Imperial College London have created detailed 3D computer models of two fossilised specimens of ancient creatures called Cryptomartus hindi and Eophrynus prestvicii, closely related to modern-day spiders. The study reveals some of the physical traits that helped them to hunt for prey and evade predators.
The researchers created their images by using a CT scanning device, which enabled them to take 3,000 x-rays of each fossil. These x-rays were then compiled into precise 3D models, using custom-designed software.
…Cryptomartus hindi had ball-like growths at the base of its limbs, called coxal endites. The scientists believe the coxal endites could be an evolutionary hang-over from their last common ancestor, who probably used the growths at the base of their limbs to help them grind their food. These coxal endite-type growths can still be seen today in species such as horseshoe crabs, which use them to grind up their prey before pushing it into their backward-facing mouths.
The computer models also revealed that Cryptomartus hindi’s mouth appendages, called pedipalps, had tiny ‘tarsal’ claws attached at the end to help the creature to manipulate its prey. These claws are seen in rare modern-day arachnids such as the Ricinulei. The researchers say that the existence of this common physical feature, shared by the Cryptomartus hindi and the Ricinulei, lends further weight to the theory that they are closely related.
The models also reveal new information about Eophrynus prestivicii. Previous studies of fossilised remains of this creature suggested that it could have hunted on the open forest floor. It had long legs that enabled it to run through leaf litter to chase, catch and kill its prey.The new models reveal, for the first time, that Eophrynus prestivicii had defensive spikes on its back. The researchers say that the spikes may have been a defensive adaption by Eophrynus prestivicii, to make them a less tempting meal for the amphibians that would have recently emerged from the oceans onto land.