A new species of predatory tyrannosauroid dinosaur that lived about 92 million years ago (Cretaceous period) has been identified from fossils found in New Mexico.
The new dinosaur, named Suskityrannus hazelae, was a tiny relative of Tyrannosaurus rex, about 9 feet (2.7 m) long and 3 feet (0.9 m) tall at the hip.
The ancient creature weighed between 20 and 41 kg, compared to a Tyrannosaurus rex’s weight of up to 9 tons.
Its diet likely consisted of the same as its larger meat-eating counterpart, with Suskityrannus hazelae likely hunting small animals.
“Suskityrannus hazelae gives us a glimpse into the evolution of tyrannosaurs just before they take over the planet,” said Dr. Sterling Nesbitt, a paleontologist in the Department of Geosciences at the Virginia Tech College of Science.
“It also belongs to a dinosaurian fauna that just proceeds the iconic dinosaurian faunas in the latest Cretaceous that include some of the most famous dinosaurs, such as Triceratops, predators like Tyrannosaurus rex, and duckbill dinosaurs like Edmontosaurus.”
Two partial skeletons of Suskityrannus hazelae were found on 1990s expeditions to the Zuni Basin in western New Mexico.
“Suskityrannus hazelae has a much more slender skull and foot than its later and larger cousins, Tyrannosaurus rex,” Dr. Nesbitt said.
“The find also links the older and smaller tyrannosauroids from North America and China with the much larger tyrannosaurids that lasted until the final extinction of non-avian dinosaurs.”
The findings were published in the journal Nature Ecology Evolution.
Sterling J. Nesbitt et al. A mid-Cretaceous tyrannosauroid and the origin of North American end-Cretaceous dinosaur assemblages. Nature Ecology Evolution, published online May 6, 2019; doi: 10.1038/s41559-019-0888-0