Amber is an extremely valued material, due to the unique process of its creation and the precious elements it often hides within. It is found in a few locations in the world, and it has been used in jewelry pieces and for natural healing for more than 50 million years.

Amber is a fossilized tree resin and can have green, red, and blue hues. During its formation, it might pick up various items from the surface, like insects, bark, or leaves, and they get trapped in it and become fossils.

These fossils often reveal important facts about the development of species throughout the years.

Two independents teams investigated amber mined in Myanmar for jewelry. The four 100-million-year-old specimens of spiders resembled a cross between a spider and a scorpion.

Prashant Sharma, an evolutionary developmental biologist at the University of Wisconsin in Madison, who was not involved in the work, stated that the discovery “could help close major gaps in our understanding of spider evolution.”

The group of arachnids contains spiders, scorpions, and ticks, and spiders. Spiders have been here for around 300 million years and are known for their spinnerets, which are modified “legs” that produce silk and control its extrusion from small pores called spigots. Male spiders have another modified “leg”, used to insert sperm into the female.

The segmented abdomens of the scorpions are believed to have diverged from an ancestral arachnid more than 430 million years ago.

In 1989, researchers found a spigot-bearing fossil that was 100 million years older than the earliest known spider. Yet, by 2008, paleobiologists understood that it was just a spider relative, and probably a stepping stone to true spiders. They enlisted it into the group Uraraneida, believed to have thrived between 400 million and 250 million years ago.

Several years ago, two independent paleobiologists at the Nanjing Institute of Geology and Paleontology in China were shown specimens that looked like 5-millimeter-long Uraraneida encased in amber.

One of them, Wang Bo, investigated two specimens of the creature, which was later named Chimerachne yingi (“chimera spider” in Latin). The team of the other paleobiologist, Huang Diying, examined a different pair of the fossils.

Teams found out about each other when the results of both teams were published in the same journal.

Gonzalo Giribet, an invertebrate biologist from Harvard University and an author on one of the papers, wrote:

“Take the front of a spider, the end of a vinegarroon and then you put spinnerets on it and that’s our fossil.”

Greg Edgecombe, a paleobiologist at the Natural History Museum in London, said:

“The material is stunning in the quality of its preservation. It throws up a combination of characters that initially seems alien to an arachnologist.”

He explained that despite some differences, both teams came to the same conclusion, “ that fossil uraraneids, as this group is called, are the closest extinct relatives of spiders.”

The specimens of the first team revealed the top of this organism and the ones of the other group provided a good look at the underside.

Sharma explained:

“The presence of the spinnerets, means they must have originated “very early” in arachnid evolution. The male specimens also have the special appendages for inserting sperm into the female. “

It was not confirmed, but it was believed that the tail as used for sensing.

According to paleontologist and arachnologist Paul Selden of the University of Kansas, that worked in one of the teams:

“Any sort of flagelliform appendage tends to be like an antenna. It’s for sensing the environment. Animals that have a long whippy tail tend to have it for sensory purposes.”

“We don’t know if it wove webs. Spinnerets are used to produce silk but for a whole host of reasons -- to wrap eggs, to make burrows, to make sleeping hammocks or just to leave behind trails. If they live in burrows and leave, they leave a trail so they can find their way back.”

An evolutionary biologist at Auburn University in Alabama, Jason Bond, who was not involved with the work, said that the creatures look like “spiders with tails.”

Therefore, early arachnids possessed a mixture of these traits, and they were selectively lost over time, leading to the look of arachnids we know today.

Bond added:

“And what is even more amazing is that the amber is only 100 million years old. So these spider relatives hunted side by side with spiders for 200 million years.”

Sources:
www.sciencemag.org
www.sciencealert.com
www.nytimes.com