The holotype, or first specimen, of the new arachnid species Chimerarachne yingi. Photo / Bo Wang.
The holotype, or first specimen, of the new arachnid species Chimerarachne yingi. Photo / Bo Wang.
Deep in a tropical rain forest, during a time when dinosaurs walked the Earth, four itsy bitsy spiders crawled down a tree, got stuck in some sticky resin and never climbed up again.
Some 100 million years later, blocks of amber containing their fossilised forms wound up on the desksof two scientists in China. Both researchers looked at the perfectly preserved animals and came to the same conclusion: This was an entirely new kind of animal.
They introduced their discovery, dubbed Chimerarachne yingi, in a pair of papers published today in the journal Nature Ecology and Evolution.
With its curious mix of ancient and modern traits - a long, skinny tail inherited from a distant arachnid ancestor, but a silk-producing organ like those found in spiders today - the tiny chimerarachne, or "chimera spider," is not a member of the immediate family.
But it is one of modern spiders' closest cousins, and it presents some intriguing hints at how they evolved.
The C. yingi fossils were uncovered by amber miners in northern Burma, sold to dealers, then purchased by researchers at the Chinese Academy of Sciences. By coincidence, two sets of the fossils became available around the same time, and Bo Wang and Diying Huang - colleagues in the academy's paleobiology lab - began to analyse them almost simultaneously.
Neither was aware of what the other was up to until they submitted their studies for publication. Happily, their results were close enough that the journal opted to publish both papers.
Both describe creatures so small they could fit on the tip of a fine-point pen, with eight legs and tiny but formidable fangs. Their hindquarters bear spinnerets, the same organs from which living species spin their silken webs. The males also have modified pedipalps - syringe-like appendages on the fronts of their faces that modern spiders use during mating.
The holotype, or first specimen, of the new arachnid species Chimerarachne yingi. Photo / Bo Wang.
Other features of chimerarachne appear much more primitive. Their torsos are segmented, like those of older arachnid groups, and they have long, whip-like tails, called telsons, that seem to be inherited from a more primitive ancestor. This mix of features gave the spiders their name: a reference to a mythical creature with a lion's head and serpent-like tail.
This odd appendage, which is absent in modern spiders, can be found in vinegaroons, a group of nightmarish scorpion-looking creatures that lives today. And it's visible in one of the oldest fossils from a close spider relative, Attercopus fimbriunguis, which dates back 380 million years.
