New details of Tully monster revealed

Newswise —

The Tully monster (Tullimonstrum gregarium), a puzzling creature that existed around 300 million years ago, has been a source of bewilderment for paleontologists for over half a century due to its unusual anatomy defying easy categorization. Recently, a group of researchers put forth a hypothesis proposing that the Tully monster was a type of vertebrate akin to jawless fish like lamprey and hagfish, which would fill a gap in the evolutionary timeline of early vertebrates. However, this hypothesis has been both supported and refuted by various studies. Now, a team of scientists in Japan has utilized cutting-edge 3D imaging technology to shed light on the matter, and their findings strongly indicate that the Tully monster was not a vertebrate. Nevertheless, the exact classification and identification of this enigmatic creature as an invertebrate is still pending further investigation.

During the 1950s, Francis Tully stumbled upon a peculiar creature while indulging in his hobby of fossil hunting in Mazon Creek Lagerstätte, located in Illinois, USA. This marine "monster," measuring an average of 15 centimeters, dated back 300 million years and soon became a subject of intrigue among researchers. Unlike the fossilized remains of dinosaurs or hard-shelled organisms, the Tully monster had a soft body, posing a challenge for taxonomic classification. Mazon Creek Lagerstätte is renowned for its exceptional preservation of marine animals in detailed imprints within underwater mud, a rare occurrence in the fossil record. In 2016, a hypothesis emerged from a group of scientists in the US, suggesting that the Tully monster may be a vertebrate, potentially filling a crucial gap in the understanding of vertebrate evolution.

The long-standing debate over whether the Tully monster was an invertebrate or a vertebrate may have finally come to a resolution, thanks to recent research conducted by a team from the University of Tokyo and Nagoya University. Despite numerous studies presenting conflicting evidence, the team's findings have shed new light on the mystery. "We believe that the mystery of it being an invertebrate or vertebrate has been solved," said Tomoyuki Mikami, a former doctoral student at the University of Tokyo and currently a researcher at the National Museum of Nature and Science. "Based on multiple lines of evidence, the vertebrate hypothesis of the Tully monster is untenable." The team's research revealed that the Tully monster displayed segmentation in its head region that extended from its body, a characteristic not observed in any vertebrate lineage. This strongly suggests that the Tully monster had a nonvertebrate affinity, putting an end to the long-debated question of its classification.

The team of researchers embarked on an extensive study, analyzing more than 150 fossilized Tully monsters and over 70 other animal fossils from Mazon Creek. To aid their investigation, they utilized advanced technology, including a 3D laser scanner, to create detailed, color-coded maps of the fossils in three dimensions. These maps revealed subtle surface irregularities through color variation. In addition, the team employed X-ray micro-computed tomography, a technique that uses X-rays to generate cross-sectional images of an object, allowing for the creation of a 3D model. This approach was used to examine the proboscis, an elongated organ located in the head of the Tully monster. The resulting 3D data revealed that the characteristics previously thought to indicate vertebrate features were actually inconsistent with known vertebrate anatomy. This further supported the conclusion that the Tully monster was not a vertebrate, challenging the previous hypothesis and providing new insights into its classification.

While the recent study has provided evidence that the Tully monster was not a vertebrate, the exact classification of this enigmatic creature is yet to be determined. The researchers believe that the Tully monster may belong to a different group of organisms altogether, possibly a nonvertebrate chordate such as a lancelet, or a protostome, which is a diverse group of animals that includes insects, roundworms, earthworms, and snails. However, due to the radically modified morphology of the Tully monster, further investigation is needed to shed light on its true taxonomic position. This intriguing creature continues to captivate paleontologists, and future research may provide new insights into its evolutionary history and its place in the tree of life.

The Tully monster serves as a prime example of the challenges faced by paleontologists in unraveling the complex history of Earth and its diverse inhabitants. Many intriguing organisms, like the Tully monster, have not been well-preserved as fossils, making it difficult to piece together their evolutionary significance. However, the fossils from Mazon Creek Lagerstätte provide invaluable paleontological evidence that cannot be obtained from other sites. As Tomoyuki Mikami pointed out, further research on these fossils is crucial in extracting important clues that can help us better understand the evolutionary history of life on our planet. The enigmatic Tully monster continues to be a fascinating subject of study, highlighting the ongoing quest to uncover the secrets of Earth's past and the diversity of its ancient inhabitants.

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