When the concretion from the lab was prepared, the team discovered that a previously undiscovered species of dinosaur had been preserved in perfect articulation. This included part of the spine, hips, and complete legs, all encased together and indicating that the dinosaur was buried and preserved before its body decayed and parts scattered. Finding dinosaur bones still in articulation with each other is quite rare, especially given the amount of sediment needed to bury such a large animal.
Upon studying Koleken’s vertebrae and femur fossils, technicians were able to make detailed observations about the dinosaur’s anatomy. The small arms and evidence of a deadly bite found in these fossils provide additional insight into the behavior and characteristics of this new species. Paleontologist Mauricio Cerroni, who was not involved in the study, found the arguments put forth by the authors to be very compelling, further supporting the significance of this new discovery. Although it wasn’t immediately clear that Koleken was a new dinosaur, as a famous carnivore named Carnotaurus had been named from the same geologic formation in 1985, further analysis revealed that the bones belonged to an entirely different species. The absence of horns and other traits typical of Carnotaurus led scientists to believe that they had discovered a new species of carnivore that no one had ever seen before.
