New Species of Dinosaurs 'Khankhuuluu Mongoliensis' Sheds Light on Tyrannosaurus Family Tree

Dinosaurs have always been intriguing creatures to study for experts. Now, researchers have made another breakthrough in figuring out the legacy of these beasts, according to the BBC. They have uncovered a new species of dinosaur by analyzing two specimens. Findings regarding this new species have been published in the journal Nature. Named as Khankhuuluu (pronounced khan-KOO-loo) mongoliensis, which translates to "Dragon Prince of Mongolia." The researchers did the identification based on two specimens present in the collection of a Mongolian museum. Both specimens were estimated to be around 86 million years old. Further analysis revealed the species to be the closest known ancestor of all tyrannosaurs, a group that includes the popular T. rex.

The species appears to predate Tyrannosaurus by around 20 million years, according to The Independent. It was a mid-sized dinosaur standing around 13 feet in height and weighing on average 1,600 pounds. The creature walked on two legs and exhibited a long snout accompanied by sharp teeth. The features suggested the creature was a swift predator, hunting small prey. Since Khankhuuluu shared several anatomical traits with tyrannosaurs but not defining characteristics, researchers proclaimed it to be a predecessor but not a part of the tyrannosaur lineage. It means that they were of a different species from which tyrannosaurs evolved.

"Khankhuuluu was almost a tyrannosaur, but not quite. For example, the bone along the top of the snout and the bones around the eye are somewhat different from what we see in tyrannosaurs. The snout bone was hollow and the bones around the eye didn't have all the horns and bumps seen in tyrannosaurs," Paleontologist Darla Zelenitsky of the University of Calgary in Canada and a lead author of the study shared. The finding has been deemed valuable, as it fills a crucial early gap in the available fossil record of tyrannosaurs, according to CNN. The filling of this gap could help experts understand how tyrannosaurs eventually evolved into becoming the apex predators of their habitats. The species was allegedly labeled as a 'prince' due to its smaller size compared to many of its close relatives, like Tyrannosaurus rex, whose name translates to "the tyrant lizard king."

The two specimens examined in the study were partial skeletons uncovered from Mongolia's Gobi Desert in 1972 and 1973. Experts think that Khankhuuluu mongoliensis was possibly a transitional species between earlier tyrannosauroid species and tyrannosaurs. Insights from Khankhuuluu mongoliensis indicated that tyrannosauroids conducted three migrations between Asia and North America, causing them to diversify and eventually become the massive beasts that terrorized North America in the late Cretaceous Period.

The finding forced researchers to re-work the family history of tyrannosaurs available to them, per The Independent. Before the discovery, there was a lot of debate on how one group was related to others in the family tree. Analysis of the two specimens challenges some past assertions. China's Qianzhousaurus, also known as 'Pinnochio-rexes' because of its long snout, was believed by some to be an ancestor of the giant tyrannosaurs like Tyrannosaurus rex. However, the prominent difference between Qianzhousaurus and Khankhuuluu mongoliensis indicates that the ancestral theory was possibly wrong. 

Zelenitsky believes that the findings show that the tyrannosaur family did not take a straightforward path to evolution. It did not develop from small sizes in early species to larger sizes in later species. Examination of Khankhuuluu mongoliensis also reveals that tyrannosaur ancestors lived in Asia. "Around 85 million years ago, these tyrannosaur ancestors crossed a land bridge connecting Siberia and Alaska and evolved in North America into the apex predatory tyrannosaurs," lead study author Jared Voris, a postdoctoral scholar at the University of Calgary, shared.

After the evolution, one group of North American tyrannosaurs returned to Asia and diversified into two branches, "Pinnochio-rexes" and Tarbosaurus. The tyrannosaurs then returned to North America and eventually transformed into giant creatures like T Rex. This "king" dominated western North America until it vanished 66 million years ago, along with other dinosaurs. Experts believe there is still much more to be uncovered about the evolution, as there is a 20-million-year gap between Khankhuuluu mongoliensis and tyrannosaurs.