Spiders with tails, ew.
A list of things creepier than spiders: parasitic worms, ticks, ancient proto-spiders.
What, you may ask, is a proto-spider? It's the thing that preceded spiders in evolution—the first attempt, the dry run. Thanks to two international teams of paleobiologists, we now have a collection of four proto-spider specimens preserved in amber and dating back some 100 million years. Their work is published this week in two papers in Nature Ecology and Evolution.
The spiders are of the type Chimerachne yingi, a name that translates from Latin to “chimera spider.” This is meant to reflect its evolutionary "in-betweenness." C. yingi has a lot in common with the scorpion, an arachnid that predates the oldest spider by about 100 million years, including a segmented body and a long tail-ish appendage. At the same time, they share some spider-like sex organs as well as spinnerets, the organs spiders use to produce silk.
All of the samples came from amber mines in Myanmar via fossil dealers. The two groups of researchers, both originating at Nanjing Institute of Geology and Paleontology in China, were independently approached by dealers and weren't actually aware they were studying the same thing until after they'd submitted their papers to the same journal, which seems weird. Generally, one paper looks at the top part of the spider, while the other focuses on the bottom part.
C. yingi is the closest extinct relative of spiders. Part of what makes this interesting is that the species actually co-existed with spider-spiders for at least 100 million years before dying off.