The dinosaur was named D. horneri after the renowned paleontologist John “Jack” R. Horner, a former curator of the Museum of the Rockies in Bozeman, Montana.
The researchers conducted work that co-author Jayc Sedlmayr of the Louisiana State University Health Sciences Center New Orleans described as “arm deep in blood and guts,” dissecting birds, alligators, and crocodiles to see how facial nerves and arteries leave traces on bones. The scientists then used this information to flesh out the face of Horner’s Frightful Lizard that included small horns above the eyes.
The dinosaur’s super-sensitive snout likely would have been important “for prey manipulation, feeding, and for reproduction, such as building a nest, manipulating eggs, and safely moving hatchlings,” co-author David Varricchio, a professor at Montana State University, told Seeker.
He added that the snout could therefore function like an arm, given that “the small arms of tyrannosaurs were likely not effective at any of these tasks.”
The tender snout also appears likely to have served a sensual purpose when it came to mating.
“In courtship, tyrannosaurids might have rubbed their sensitive faces together as a vital part of pre-copulatory play,” says the report.
Horner’s Frightful Lizard used its snout skills to help devour prey that included horned, crested duckbill and dome-headed dinosaurs, in addition to much smaller carnivorous dinos, the researchers believe.
Carr said that “killing would have been the work of the jaws,” with their sensitive margins likely giving the hunter “important information regarding how hard to bite, whether or not the prey was still living, and the locations of soft and hard parts.”
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The dinosaur’s similarities with today’s crocodiles and alligators are evidence of a genetic inheritance from a shared ancestor.
“Crocodylians are not dinosaurs, and dinosaurs are not crocodylians," Carr clarified, "but they do share a common ancestor.”
Birds, on the other hand, are considered to be living dinosaurs. Birds probably inherited their lack of lips from their equally lipless dino ancestors, according to the scientists.
The researchers further believe that Horner’s Frightful Lizard evolved via a rare form of speciation known as anagenesis, where one species gradually morphs into a new one over time.
Co-author Jason Moore of the University of New Mexico explained that he most common form of speciation, known as cladogenesis, “most frequently occurs by a small population of one species being separated from the remainder of the members of that species and being subject to a different set of environmental conditions, and hence evolving different sets of traits."
"With a small population with limited genetic exchange, this can produce the genetic shifts that lead to speciation relatively quickly and easily,” he added. “With anagenesis, however, the entire parent species population is shifting traits to produce the new species. This would imply a broader, although not necessarily more severe, set of changes in the physical or biological environment of Daspletosaurus.”
It has even been theorized that some human ancestors evolved by anagenesis, but this idea has largely fallen out of favor in recent years.