The nature of the Tullimonstrum gregarium, or Tully monster, has confused scientists ever since it was first found. Now, a new study finally sheds light on this paleontology mystery.
Tully Monster: Vertebrate or Invertebrate?
Science Alert notes that, for the past decades, scientists have gone back and forth in claiming that the Tully monster was a vertebrate or invertebrate. This taxonomic difficulty was because of the creature's strange anatomy.
The Tully monster had a length of around 15 centimeters, and its tail had fins that were similar to those of a cuttlefish. It also had protruding eyes and a narrow proboscis.
Unlike hard-shelled creatures and dinosaur bones that were often recovered and preserved, the Tully monster had a soft body. Science Daily reports that the Mazon Creek Lagerstätte, where the fossilized creature was first recovered, is among the world's few areas where it would be just right for these animals' imprints to be documented in the mud below the water.
There have been no bone structures recovered in any Tully monster fossils, but such a factor is not diagnostically sufficient. Skeletons of cartilage, which can be found in certain vertebrate fish, would not have been preserved like bones.
Thus, whether the Tully monster is a vertebrate or invertebrate has remained a long-standing mystery. Though much effort has been exerted to support and reject the hypothesis, a unified consensus has not been achieved. However, now, with a recent study, this debate could finally reach its end.
300-million-year-old Tully Monster Did Not Have Bones
Tomoyuki Mikami, a paleontologist who was at the University of Tokyo when the study was being conducted but is now working at the National Museum of Nature and Science, says that they think the mystery regarding the creature's bone structure has been solved. Mikami notes that, according to several lines of evidence, the vertebrate hypothesis seems untenable.
Interestingly, the Tully monster had a specific segmentation in its head that reached out from its body. Such a feature has not been observed among any vertebrates, which, thus, suggests that the creature was indeed a nonvertebrate.
To delve deeper into this issue, Mikami and his team gathered over 150 specimens of Tully monsters as well as over 70 fossils of different creatures from the fossil bed of Mazon Creek. They subjected each specimen to 3D laser scanning that was high-resolution and X-ray microcomputed tomography. Their study was published in the Palaeontology journal.
The researchers looked into structures that were seen to harbor vertebrate features. However, the researchers found that none of these could compare to the structures present in vertebrates. Science Alert notes that what was seen as myomeres were entirely different from the structures in vertebrates. Moreover, the vertebrate-like gill pouches, fin rays, cartilages, and brain were totally absent. To add, the proboscis teeth are very different from lampreys, which is contrary to earlier comparisons.
Considering how unique the creature is, it is no wonder that scientists have been confused by its anatomy and taxonomy. Now that the researchers know that it does not have any bones, they are now set to know the type of invertebrate that it was.
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