The Tully Monster, one of the weirdest creatures that ever lived, has finally been identified
For more than half a century, scientists have scratched their heads over the nature of an outlandishly bizarre creature dubbed the Tully Monster that flourished about 307 million years ago in a coastal estuary in what is now northeastern Illinois.
But researchers on Wednesday announced they have finally solved the mystery.
“I would rank the Tully Monster just about at the top of the scale of weirdness,” said paleontologist Victoria McCoy of Britain’s University of Leicester, who conducted the study while at Yale University.
It boasted a torpedo-shaped body, a jointed, trunk-like snout ending in a claw-like structure studded with two rows of conical teeth, and its eyes were set on the ends of a long rigid bar extending sideways from the head. Up to about 35cm long, it had a vertical tail fin and a long, narrow dorsal fin.
A sophisticated reassessment of the fossils determined it was a vertebrate, with gills and a stiffened rod, or notochord, that functioned as a rudimentary spinal cord and supported its body. The notochord previously had been identified as the gut.
There are some body differences between lampreys and the Tully Monster: Modern lampreys have the same long, tube-like bodies, but they have small tail fins and long dorsal fins. Tully Monsters had the opposite. McCoy suggests that the Tully Monster may have evolved to propel itself forward with tail movement, as opposed to its close relatives that had bodies made for full-body wiggling.
In other words, even if T. gregarium really was a lamprey, it was still an oddball.
Tullimonstrum shared its shallow marine environment with fish including sharks as well as jellyfish, shrimp, amphibians and horseshoe crabs.
“It fed by grasping things with the proboscis [snout] and scraping bits off with its tongue. We don’t know what it ate or if it was a predator or scavenger,” McCoy said.
It is called the Tully Monster in honour of amateur fossil-hunter Francis Tully, who first found it in Illinois coal-mining pits in 1958 and brought it to experts at the Field Museum in Chicago.
“This puzzle has been gnawing at paleontologists,” said Field Museum paleontologist Scott Lidgard, whose museum holds 1,800 specimens of Tullimonstrum, the official state fossil of Illinois. “I was blown away when the results started coming in.”
The research was published in the journal Nature.
Assuming no one upends the Tully Monster’s new designation, scientists can now focus on figuring out how the strange critter lived based on what we know about its close relatives. It may have found a phylum, and perhaps even an order, but the state fossil of Illinois has plenty of mystery left.
“There are plenty of fossils that are really enigmatic, but the Tully Monster has always been kind of in a class of its own,” said McCoy.
Additional reporting by The Washington Post
