Fossil of a 308-million-year-old spiny-legged spider ancestor found

Once an arachnid species that crawled through the carboniferous coal forests of North America and Europe has now been traced back to an ancient species of arachnid called Douglassarachne acanthopoda.

A team of researchers from the University of Kansas, the Natural Museum of London and the Museum für Naturkunde Berlin analyzed a fossil discovered by Bob Masek in the 1980s. It was later acquired by the David and Sandra Douglass Collection.

This fossil was recently examined to understand more about the diversity and evolutionary history of arachnids during the Carboniferous period.

Ancient arachnid fossil about 308 million years old

Douglassarachne acanthopoda represented several features, such as robust and spiny legs, that scientists consider an important specimen for studying ancient arachnid adaptations and their ecological role in prehistoric environments.

Douglassarachne acanthopoda comes from the famous site of Mazon Creek in Illinois and is approximately 308 million years old,” said lead author Paul Selden of the University of Kansas and the Natural History Museum of London.

“This compact arachnid had a body length of about 1.5 centimeters and is characterized by its remarkably robust and spiny legs, making it quite unlike any other known arachnid, living or extinct.”

The analysis was intended to help paleontologists understand the variety of body plans that existed among arachnids and how these forms evolved or became extinct over time.

The spider-like fossil was found in the clay-ironstone concretion, a type of rock formation known to occasionally preserve fine details of ancient species.

It was examined at the Field Museum of Natural History in Chicago, where researchers suspected that the mouthparts were not clearly visible, making it challenging to characterize the species within a specific arachnid order.

Some facets made the characterization inconclusive

Scientists noted that despite the clear visibility of the legs, the other parts made the characterization inconclusive.

They also noted that coal measures played a crucial role in the Carboniferous by providing a rich source of well-preserved fossils, including the newly described arachnid species. These rock layers provide valuable insights into the diversity and evolution of ancient life during the Carboniferous.

According to the statement, the fossil arachnids represented the first time in Earth’s history that most living groups of arachnids occurred together.

“Spiders were a fairly rare group, known at the time only from primitive lineages, and they shared these ecosystems with several arachnids that have long been extinct,” says co-author Jason Dunlop of the Museum für Naturkunde Berlin.

Douglassarachne acanthopoda is a particularly impressive example of one of these extinct forms. The fossil’s very spiny legs are reminiscent of some modern harvestmen, but its body plan is very different from that of a harvestman or any other known group of arachnids.”

He said the fossil could belong to a broader group including spiders, whip spiders and whip scorpions. However, it was confirmed that these spiny arachnids appear to have originated from a time when arachnids experimented with a range of different body plans, whatever their evolutionary affinities may have been.

“Some of these later became extinct, perhaps during the so-called ‘Carboniferous Rainforest Collapse,’ a time shortly after the Mazon Creek era, when the coal forests began to fragment and die. Or perhaps these strange arachnids persisted until the end of the Permian mass extinction?”


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Shubhangi Dua As a quirky and imaginative multimedia journalist with a Masters in Magazine Journalism, I’m always thinking of new ideas and finding innovative ways to tell stories. I’ve dabbled in a variety of mediums, from wielding a pen as a writer to capturing moments as a photographer and even strategizing on social media. With my creative mind and eye for detail, I have worked in the dynamic landscape of multimedia journalism, writing on sports, lifestyle, arts, culture, health and wellbeing at Further Magazine, Alt.Cardiff and The Hindu. I’m on a mission to create a media landscape as diverse as a Spotify playlist. From India to Wales and now England, my journey has been filled with adventures that inspire my paintings, cooking and writing.

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