This is Mazon Monday post #233. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
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As you probably know, the Tully Monster is the State Fossil of Illinois. It a real fan favorite. Everyone loves the Tully Monster... did you know there are stuffed Tullys you can buy online?!?
Last week, the Chicago Tribune did a vintage article called "How the Tully monster became Illinois’ official state fossil".
One small event made Francis Tully’s life extraordinary.
Almost 70 years ago, the Texaco pipe fitter and amateur explorer found something inside a rock previously unseen by humans. The rust-colored rock, or nodule, held inside it a small creature that had been hidden away for millions of years.
“When you’re hunting fossils, you’re looking for just anything at all,” Tully told Tribune reporter Peter Gorner in 1987. “The kick is to find something nobody has found before. Then, the idea is to share the things with others. That’s why I seldom have sold any. I trade them off or give ’em away.”
What Tully and geologists long had known is something many Chicagoans don’t — just about 50 miles south of the city is one of the world’s great fossil beds. Mazon Creek, south of Morris, was once home to the Sea of Illinois, part of a warm, shallow saltwater estuary that stretched across much of the Midwest about 90 million years before the first dinosaurs. Its lush trees and swamps were the perfect environment for fossil preservation for the many plants and animals that lived there — especially invertebrates (creatures without backbones). And since part of the area near Braidwood had been strip-mined by coal companies during the early 20th century, giant piles of soft shale provide a gold mine for fossil fanatics.
Tully’s discovery baffled scientists, who eventually christened the creature after the Lockport resident. Tully’s monster was recognized as the official state fossil of Illinois 35 years ago this week, but the designation did not come without hiccups along the way — and, unfortunately, arrived too late for its staunchest advocate to celebrate.
The Tully monster’s discoverer, Francis Tully, at a Field Museum Members’ Night in 1987. (Ron Testa/Field Museum)
“I found two rocks that had cracked open from natural weathering,” Tully told the Tribune about his major discovery near Mazon Creek. “They held something completely different. I knew right away. I’d never seen anything like it. None of the books had it. I’d never seen it in museums or at rock clubs. So I brought it to the Field Museum to see if they could figure out what the devil it was.”
A Tully monster holotype fossil — the fossil that’s used as a “Platonic ideal” — shows the characteristics of the species to which all other specimens are compared. (Paul Mayer and Alex Layng/Field Museum)
When Tully brought the specimen to the Field Museum, its experts confessed they didn’t know what it was.
“We could not even decide which phylum to put it in,” Eugene S. Richardson Jr., then curator of fossil invertebrates, later wrote. “And that was a serious and embarrassing matter.”
A decade later, Richardson decided the creature finally needed a name. In an excerpt published in Nature, Richardson merely Latinized what everyone was calling the thing, anyway: Tullimonstrum gregarium — Tully monster, common.
“I was very pleased,” Tully told the Tribune about the name in 1986. “Darn right.”
Richardson gave the creature the nickname "Mr. Tully's Monster", as he was unsure how to classify it. The nickname stuck, becoming the origin of its name. The animal was new to science as no one had seen anything quite like it. In the Tully's description in 1966, Richardson famously wrote "While this obscure but plentiful animal is being studied, I prefer not to assign it to a phylum." Later, in a paper with Ralph Gordon Johnson, they wrote "There is no compelling reason to assign Tullimonstrum to any of the known phyla. It could be imagined as an aberrant member of one of several phyla but the critical evidence is not available."
A Tully monster graphic shows the size, shape and science of the Tully monster. (Phil Geib/Chicago Tribune)
The so-called monster that once inhabited swamps in Will, Kankakee and Fulton counties was now considered for the state’s official fossil.
“I don’t believe there are a series of fossils of the import to the state like the Tully monster,” said Rep. Helen Satterthwaite ,D-Champaign, who sponsored the bill.
The Tully monster, though mysterious, put Illinois on the map for fossil hunters, Illinois State Museum curator of geology Richard Leary told the Tribune in March 1987.
The Tully monster was first considered a contender for the official state fossil of Illinois in March 1987. (Chicago Tribune)
After an almost two-year delay, Gov. Thompson finally signed legislation making the Tully monster the official state fossil in Illinois.
Here is an article about the desgination. It appeared in Andy Hay's "Creature Corner" and later in an ESCONI book by the same name.
State fossil, prairie grass chosen
Springfield--
The "Tully Monster" became Illinois' official state fossil! This was just one day after the "Big Bluestem" became Illinois' official state prairie grass.
Governor James R. Thompson signed into law both the fossil bill, sponsored by Rep. Larry Wennlund, R-New Lenox, and the prairie grass bill, sponsored by Rep. Tom Ryder, Rerseyville.
The Tully Monster and Big Bluestem are the latest additions to official Illinois symbols, which include the oak, violet cardinal, fluorite, monarch butterfly, white tailed deer and bluegill. Several, including the oak, violet, cardinal and blue- gill, were elected by Illinois school children.
Wennlund said his bill simply declared the Tullimonstrum gregarium to be the official state fossil because it is unique and there would not have been any opposition in a school election.
Amateur collector Francis Tully found the first stone impressions of the 300 million year old sea animal in the late 1950's in the Will-Grundy-Kankakee county area. Wennlund said it was a foot long, and had a soft body and ate meat.
The Big Bluestem, one of several prairie grasses that made Illinois soil rich, was still growing to heights of eight feet in the early 1800's. It had a three-branched seed head that gave it a nickname of turkeyfoot grass.
The Big Bluestem won its designation by beating Indiangrass, Prairie Dropseed and Little Bluestem in a 4316 vote contest at 50 grade schools.
(NOTE: Francis Tully was an ESCONI member.)
Recently, there have been attempts to classify the Tully Monster. The latest, by McCoy et al in 2016, again in 2016 by Clements et al, and by McCoy et al again in 2020, classify T. gregarium as a jawless fish similar to a lamprey or hagfish. If that theory is correct, the Tully Monster will fill in a gap in the evolutionary history of early vertebrates. There has been some disagreement (Sallan in 2017), although that study denies the vertebrate ancestry without proposing a viable alternative.
Some actual Tullys found by of Mr. Tully
Thanks go out to Ralph Jewell for some of the photos in this post. The Tully Monster photos come from slides he obtained from Walter Leitz. Walter and his wife Rita were a long time ESCONI collectors, who very generously contributed to The Mazon Creek Project, the science of Mazon Creek, and Mazon Creek fossil collecting in general.
