CHAMPAIGN, Ill. — A giant mollusk measuring several feet across lived in shallow marine waters in southern Illinois long before the time of the dinosaurs.
Endolobus spectabilis was one of the largest sea creatures of the time in the murky lagoons of Illinois. It was a member of the nautiloid family and had a large, coiled shell that could be two to three feet across. Its soft body parts might extend another foot outside the shell, and its tentacles even further.
It had lobes on the side of its shell, and a beak common to all cephalopods that it could use to crack open the shells of bivalves to eat or to scavenge shark remains.
An exhibit will open Thursday at the Science Center of Southern Illinois in Carbondale, with an original, life-size model of E. spectabilis – its first reconstruction – as well as a fossil shell of the mollusk.
“I thought, what a neat thing to recreate it like it was during life … so the people in the state of Illinois can see this ancient creature that was right here way before the dinosaurs,” said Joe Devera, a paleontologist with the Illinois State Geological Survey who put together the exhibit and is giving a talk on the mollusk.
One of the fossils found recently of the inner coil of a shell of the ancient mollusk, Endolobus spectabilis. Each whorl of the shell gets wider as it expands, and the entire shell would likely have been two to three feet across, said Illinois State Geological Survey paleontologist Joe Devera, who found the fossil.
The impetus for the exhibit was the discovery of several E. spectabilis fossils since 2000 around Chester, Illinois, including a large fossil found by Devera in 2013 that allowed him to pinpoint much more precisely when and where the creature lived.
The original E. spectabilis fossils were found in the 1850s and 1860s by Amos Worthen, a paleontologist for the state of Illinois, and Fielding Meek, from the Smithsonian Institution. It was the discovery of a new genus and species, but the location of their finds was vague – in Gravel Creek in Randolph County, Illinois, they wrote. And because there were no detailed records of where the fossils were in the layers of rock making up the area’s geology, it was impossible to precisely determine when E. spectabilis existed, other than sometime during the Carboniferous Period 360 million to 300 million years ago.
“It’s a huge swath of time,” Devera said. “In space and time, it had no context.”
In 2013, Devera found a large fossil in place in the rock layers. He was able to determine E. spectabilis lived in the latter part of the Mississippian Period, roughly 330 million years ago.
E. spectabilis would have been found all across southern Illinois, Devera said. At the time, Illinois was located near the equator and was “very humid and tropical. It looked quite different than today. There were large shallow seas. A large interior continental seaway flooded most of the continent.”
The mollusk likely lived in shallow lagoons, he said.
Devera worked closely with Bill Adams, a sculptor for the Science Center of Southern Illinois, to create a model of E. spectabilis based on the fossils and comparisons to modern nautiloids. The model will be unveiled at 7 p.m. Thursday at the Science Center, and Devera will discuss the creature and his work.
The model and one of the fossils Devera found will be shown at a rock, mineral and fossil show in Springfield, Illinois, during the first weekend of October. He’s hoping to arrange for them to be displayed in other regional museums next year. The model will be permanently housed at the Illinois State Geological Survey.
Editor’s notes: To reach Joe Devera, email j-devera@illinois.edu.
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