Researchers have debated the evolution of the Tully monster since the creature was discovered in the 1950s. However, there are still many mysteries about this species that have not been solved until now.

The ancient monster Tully haunted Earth’s oceans 300 million years ago and left behind fossils so bizarre that researchers don’t even know exactly if these strange creatures have a backbone. or not.

Recently, an investigation using 3D lasers discovered that the Tully monster was likely an invertebrate, but not everyone believes the results of this study. This quirky alien-looking creature is only found in the Mazon Creek fossil beds in Illinois.

They have soft bodies, eyes located on a “stalk” and a claw-like part protruding from the face. The most recent studies of the Tully monster suggest that it was a relative of the modern round-mouthed vertebrates (including lampreys) or a previously unknown species of invertebrate. Now, researchers in Japan think they have answered this question with the help of a 3D laser scanner.

“We believe the mystery of whether it is an invertebrate or a vertebrate has been solved,” said study author Tomoyuki Mikami, PhD at the University of Tokyo and a researcher at the Science Museum Tokyo National Science and Nature, said. “Based on a lot of evidence, the theory that the Tully monster is a vertebrate is not true.”

Researchers scanned more than 150 Tully monster fossils to create a color-coded 3D map of the creature’s anatomical structure. They also X-rayed a well-preserved proboscis fossil (a claw-like protrusion) to examine the creature’s teeth.

The results show that the assumption that the Tully monster is related to the round-mouthed fish and is a vertebrate is wrong. The teeth analyzed in the new study had bulging bases – unlike the teeth of roundmouth fish, which are thinner at the base. The authors say what appeared to be gills was actually just divisions in Tully’s body.

However, Victoria McCoy, an assistant professor at the University of Wisconsin-Milwaukee, is not convinced by the study. McCoy led a 2016 study that placed the Tully monster near a round-mouthed fish, and a 2020 study found that the Tully monster’s tissues are made up of vertebrate-like proteins.

“I won’t change my mind about the Tully monster, but this study is also new information that will help improve our understanding,” McCoy said. McCoy is interested in the Japanese researchers’ 3D imaging technique, but she says there are “small technical problems with some of their conclusions.”

“The actual morphology is greatly altered during the fossilization process. If you have a thousand specimens, any one feature can be preserved in hundreds of different ways,” McCoy said. Deciding where the Tully monster belongs is important because the species is so unusual that it will expand the diversity of whatever group of creatures it belongs to.

Currently, the location of the monster Tully on the evolutionary tree is still a mystery to us.