Tully monster mystery solved

Tully monster mystery solved

Tully monsters lived in Illinois 307 million years ago and they look like something out of science fiction--aquatic animals with tube-shaped bodies up to a foot long, skinny snouts ending in a toothed jaw or claw, and eyes at the end of short stalks. Field Museum scientists, along with colleagues at Yale, Argonne National Laboratory, and the American Museum of Natural History, have finally figured out what it is.

An earlier attempt was made in 1958 by an amateur fossil collector named Francis Tully, as he discovered a prehistoric animal so bizarre that it could only be termed a monster .

Tullimonstrum gregarium, colloquially known as the Tully Monster, was a soft-bodied vertebrate that lived in shallow tropical coastal waters of muddy estuaries during the Pennsylvanian geological period, about 300 million years ago. Examples of Tullimonstrum have been found only in the Mazon Creek fossil beds of Illinois, United States. Tullimonstrum probably reached lengths of up to 35 centimetres (14 in); the smallest individuals are about 8 cm (3.1 in) long.

For decades, scientists couldn't determine what kinds of animals the monsters actually were--they were categorized as soft-bodied invertebrates, with theories ranging from worms to shell-less snails. But in a paper published in Nature, the team of scientists announced that Tully monsters are in fact vertebrates--more specifically, they're jawless fish similar to today's lampreys.

Researchers from the Chicago Field Museum brought a Tully monster fossil March 2015 to be studied under rays at Sector 8 of the U.S. Department of Energy's Advanced Photon Source at Argonne National Laboratory. Researchers that time hoped that the X-rays will give them clues to what evolutionary group the Tully monster belongs to. It lived 150 years before the first dinosaurs. Scientists disagree on its origin and whether it represents a new branch on the tree of life.

It's a beautiful example of how science works to solve mysteries of nature, and how museums fit in, said Field Museum Curator of Invertebrate Paleontology Scott Lidgard. The project relied on the Field's collection of Tully monsters--at over 2,000 specimens, the best in the world--as reference material for scientists to compare and analyze the animals' features. Digitization of The Field Museum's collections and X-ray analysis at Argonne National Laboratory helped paleontologists take a closer look at the fossils and determine what they were.

By digitizing our collections, taking photographs of our fossils and placing all of the data into a database, we made it easier for our researchers to search our collections and find specimens with new and sometimes rarely preserved evidence that may be critical for their research, explained Paul Mayer, The Field Museum's Fossil Invertebrates Collections Manager.

The monsters are related to the jawless fishes that are still around today by a unique combination of traits, including primitive gills, rows of teeth, and traces of a notochord, the flexible rod-like structure along the back that's present in chordate animals--including vertebrates like us, it was added.

Tully monsters are only found in the Mazon Creek region, one of the world's richest fossil sites, about fifty miles southwest of Chicago. Mazon Creek specimens paint a vivid picture of Illinois hundreds of millions of years ago, when the area was a swampy shoreline bordering a tropical sea. Research like this is a great way of learning where our world today comes from.

The Tully monster is a wonderful fossil that captures the imagination of every school kid, adds Mayer.

Tully monster mystery solved