A new study published in Scientific Reports has just revealed the discovery of a new species of tyrannosaur in the making Hall Lake, in New Mexico, on the border between the United States and Mexico. This species, according to the investigation carried out by the team Sebastian Dalman, paleontologist at the New Mexico Museum of Natural History and Science, lived between 73 and 71 million years ago, 7 million before the appearance of the more familiar Tyrannosaurus rex in North America.
Scientists were able to identify the new species by analyzing an ancient skull that was discovered in the sediments of Lake Hall in 1983 and mistaken for a T. rex specimen until 2013. Dalman decided to name the species Tyrannosaurus mcraeensis, with reference to McRae Grouprock layers from which the find was extracted.
Anatomical differences between this species and T. rex are very minimal, but according to scientists, the shape of the lower jaw in T. mcraeensis it is curvier and thinner than its direct successor. Furthermore, the skull also lacks several bony projections above the eyes, which are one of the typical elements of recognition T rex. However, this did not stop paleontologists from thinking that the two species were related, so much so that the two species were considered “sisters” as part of the study.
Finally, Dalman’s team counted the number of teeth and realized how to do it T. mcraeensis it had a smaller number of teeth and most likely was unable to exert the same destructive force with its bite, although it remained remarkable even by today’s standards of the animal world.
Paleontologists specify that they are not yet able to evaluate what the final dimensions of the species might have been, but Nick Longrichstudy co-author and paleontologist atUniversity of Bath, specified that it could most likely exceed 12 m and theoretically could even exceed the magnitude of a T rex adult, often mistaken by non-experts as the largest carnivorous dinosaur of its time.
The fossil material of the holotype of the species (the individual with which it was identified, with the abbreviation NMMNH P-3698) is very rare, and according to paleontologists, scientists will have a long time to analyze it to better understand the evolution of the Tyrannosaurus genus over time. It consists of a right postorbital, right squamosal, left palate, and an incomplete maxilla from the skull, as well as a left dentary, other bones, and several isolated teeth that were collected near the skull in 1983.
This species lived in that part of North America that geologists call Southern Laramidia, an island subcontinent that stretched from present-day Alaska to the northern tip of Mexico, which today joined the rest of the continent. The authors also assume that the evolution of giant tyrannosaurs in North America, a group that includes not only T rex and T. mcraeensis but also L’Albertosaurus discovered in Canada, may have been driven by the large size of their prey, which included creatures such as ceratopsids, horned dinosaurs, hadrosaurs, and ankylosaurs that were very difficult to kill due to their defensive weapons.
In recent months, reports of this group of predators have been multiplying. For example, an adolescent tyrannosaurus was recently found with an intact stomach containing food. This discovery along with the discovery T. mcraeensis and the debate over the nature of some of the controversial findings seems to demonstrate the great interest that research into these animals continues to enjoy.