Both the scientific name and the popular one (also assigned by specialists) can be misleading because Tully’s monster (Tullimonstrum gregarium) really had a strange appearance (compared to many other animals) and even threatening but, in any case, it would be a monster. tiny, if one takes into account that none of the fossils of this animal found to date exceeded 30 centimeters in length.
Regardless of its shape and size, this curious animal that inhabited the Earth -the sea, to be more exact- 300 million years ago drives paleontologists and taxonomists (biologists specialized in identifying, describing, naming and grouping all living beings) upside down. alive) since the amateur fossil hunter Francis Tully found the first specimen of this species, in 1958, in Mazon Creek, Illinois (United States).
The first scientific description of this creature was published in 1966, but even then it became clear that everything was really dark: experts could not even determine whether it was a vertebrate or an invertebrate.
In 2016, a study published in the journal Nature seemed to shed light on the darkness, listing Tully’s monsters among the primitive relatives of cyclostomous-like vertebrates (jawless fish such as lampreys and hagfish). If this hypothesis is confirmed, Tully’s monster could fill a gap in the evolutionary history of early vertebrates, said the authors of the 2016 study, whose first signatory was Victoria McCoy.
Now, five Japanese researchers have carried out a review of hundreds of fossils of this species with the help of the most advanced 3D vision techniques and their study provides new data on the morphology of this creature, as detailed in an article published in Paleontology magazine (April 16).
Firstly, the team led by Tomoyuki Mikami believes that their study shows that Tully’s monster was an invertebrate, although its exact classification and what type of invertebrate it was remains to be decided.
Mazon Creek is a paleontological site rich in fossils (what experts call a lagerstätte) and is one of the few places in the world where conditions were right to capture in detail the tracks of marine animals such as the sea monster. Tully, soft-bodied.
“We think the mystery of whether it is an invertebrate or a vertebrate has been solved,” said Tomoyuki Mikami, a doctoral student at the University of Tokyo Graduate School of Science at the time of the study and currently a researcher at the National Museum of Tokyo Nature and Science.
“Based on multiple lines of evidence, the hypothesis that Tully’s monster was a vertebrate is untenable. The most important point is that Tully’s monster had segmentation in the head region that extended from the body. This feature is not known in any vertebrate lineage, say the Japanese researchers.
The team studied more than 150 fossilized Tully monsters and more than 70 fossils of other assorted animals from Mazon Creek. With the help of a 3D laser scanner, they created color-coded, three-dimensional maps of the fossils that showed the tiny irregularities that existed on their surface through color variation. X-ray microcomputed tomography (which uses X-rays to create cross sections of an object so that a 3D model can be created), was also used to look at its proboscis (an elongated organ located in the head). These 3D data showed that the features previously used to identify Tully’s monster as a vertebrate were actually not consistent with those of vertebrates.
Although the researchers are confident from this study that Tully’s monster was not a vertebrate, the next step in the research will be to answer which group of organisms it belongs to, possibly a non-vertebrate chordate (such as a fish-like animal known as lancet) or some type of protostome (a diverse group of animals containing, for example, insects, roundworms, earthworms, and snails) with a radically modified morphology.
Troubling fossils like Tully’s monster highlight the challenge of reconstructing the dynamic history of Earth and the various organisms that have inhabited it. “There were a lot of interesting animals that were never preserved as fossils,†Mikami said. “In this regard, the investigation of the Mazon Creek fossils is important because it provides paleontological evidence that cannot be obtained from other sites. More and more research is needed to extract important clues from the Mazon Creek fossils to understand the evolutionary history of life.”
