Douglassarachne, the spiny arachnid of Mazon Creek

[Halichoeres]

From the same Carboniferous locality that gave us the Tully Monster, a spiny-legged arachnid, maybe suggesting some fairly mean predators. Its exact relationships aren't known, but it's probably not a true spider. Still, a very cool addition to the Mazon fauna.

Fossil and interpretive diagram:


Open access in Journal of Paleontology: https://www.cambridge.org/core/journals/journal-of-paleontology/article/remarkable-spiny-arachnid-from-the-pennsylvanian-mazon-creek-lagerstatte-illinois/0E1B32BAFCAEA067018EF9BF349F8B81

[Totoro]

This is so very cool.  I grew up near the Braidwood, Illinois region of the Mazon Creek Lagerstatte and visited it once with a botany class where I was lucky enough to find a nodule with a nice fern leaf inside.  It's still a treasured possession that evokes fond memories.    I'd love to return to it one day, but not sure what it would take to get permission to collect there.   

[Bowhead Whale]

Very weird creature indeed. It looks a lot more like a giand acarid than a real spider. I have, in my life, never seen a spider with a segmented abdomen. Do you think this fossilized animal was a true arachnid? It does have the right number of legs, of course, but its segmented body makes me wonder...

[Ludodactylus]

Very weird creature indeed. It looks a lot more like a giand acarid than a real spider. I have, in my life, never seen a spider with a segmented abdomen. Do you think this fossilized animal was a true arachnid? It does have the right number of legs, of course, but its segmented body makes me wonder...

My first thought was that it looks like a thick-legged member of the opiliones, aka harvestmen/"daddy longlegs."

[Bowhead Whale]

Very weird creature indeed. It looks a lot more like a giand acarid than a real spider. I have, in my life, never seen a spider with a segmented abdomen. Do you think this fossilized animal was a true arachnid? It does have the right number of legs, of course, but its segmented body makes me wonder...

My first thought was that it looks like a thick-legged member of the opiliones, aka harvestmen/"daddy longlegs."

That is indeed possible. Do we have any other example of thick-legged opiliones animals in fossils or in modern times? Asking by sheer curiosity.

[Halichoeres]

This is so very cool.  I grew up near the Braidwood, Illinois region of the Mazon Creek Lagerstatte and visited it once with a botany class where I was lucky enough to find a nodule with a nice fern leaf inside.  It's still a treasured possession that evokes fond memories.    I'd love to return to it one day, but not sure what it would take to get permission to collect there.   

I went with some friends last year and the permit was pretty simple, fill out online and print it out. Didn't find much but it was fun anyway!

Very weird creature indeed. It looks a lot more like a giand acarid than a real spider. I have, in my life, never seen a spider with a segmented abdomen. Do you think this fossilized animal was a true arachnid? It does have the right number of legs, of course, but its segmented body makes me wonder...

Yeah, it's definitely not a true spider, but it's more closely related to them than to harvestmen or mites. It just has this primitive segmentation, like spiders' other relatives, the amblypygids and vinegaroons.

[Cenozoic Fauna]

@Bowhead Whale regarding opiliones, there is a modern genus called Trogulus comprised of a number of species which have larger limbs than other opiliones.









Also very fascinating fossil species