Tully Monster's eyes prove it was a vertebrate



The most recent addition to the ranks of the vertebrates is the famed “Tully Monster”, state fossil of Illinois. This oddly-shaped aquatic beast, with its squid-like body and pincered mouth-on-a-trunk also had another secret. This time, it was its stalk-like “blobs.”

The state fossil of Illinois, the alien-looking Tullimonstrum, is an animal undergoing some serious image alterations. Tullimonstrum, known affectionately as the “Tully Monster”, was recently classified as an odd species of ancient fish rather than as an odd invertebrate. Yet this was not the end of its time in the limelight. New discoveries have revealed something extraordinary in the animal’s strange stalked “blobs,” one of its most distinctive features besides the pincer-bearing trunk.

These “blobs” show up in the animal’s amazingly preserved fossils and also in the creature’s life reconstructions, so this was where Thomas Clements began his analysis. Clements,, a PhD student from the University of Leicester showed that these so-called “blobs” were actually filled with dark granules that had melanosomes. Melanosomes are what give the color pigments to animals, says Dr. Jakob Vinther of the University of Bristol. Vinther’s claims to fame include discovering the color of several feathered dinosaurs, a massive achievement in itself.

Now, his studies have helped to reconstruct what seem to have been the eyes of the animal. According to Clements, Vinther and Professor Sarah Gabbott, not only have they discovered Tullimonstrum’s pigments but they have also found the oldest color pigments in the fossil record. The animal dates back to the Carboniferous, so it is around 300 million years old. Professor Gabbott, from the University of Leicester's Department of Geology says that for a long time, it had been hard to conclusively classify the strange beast, and now the shape of the animal’s melanosomes helps to further cement its vertebrate status. These pigment cells are actually of more than one shape, with some resembling “meatballs” and others looking like “sausages”. This means that they were certainly vertebrates and not invertebrates, as only vertebrates have such pigment cell shapes.