Grundy County, Illinois
Range from 36 to 340 millimeters
What can this be? It’s a question that still puzzles paleontologists. Tullimonstrum was a worm-like or snail-like creature. We do know that this sea-living creature dates back some 300 million years. The fossil impression you see here came from the coal shale of Illinois.
The accompanying full-body model shows some strange features of Tullimonstrum. Its eyes are located on the ends of stalks on either side of its body. It had a long proboscis, like an elephant’s trunk, with small teeth at the end to capture prey. The proboscis delivers the prey to the mouth located in the middle under belly of the creature. It swam about powered by its squid-like tail.
The brown fossilized impression is preserved in an ironstone concretion of delta sediments that formed around the animal shortly after it died and settled to the bottom of the sea. The impression shows only the lower proboscis and upper torso of the creature. It's estimated length is 170 millimeters. This specimen shows Tullimonstrum's underside with the bar organ containing optic nerves and the left stalk of the eye structure. The tail is missing.
The drawing on the left depicts how the creatures likely lived in open ocean water near shore and aquatic plants. Tullimonstrum was preyed on by bony fishes and sharks.
Feeling creative? Try writing your own label to explain Tullimonstrum to other museum visitors in the box below.