A newly discovered diminutive T-Rex relative–Suskityrannus hazelae– sheds light on the abundance of Tyrannosauroids and their evolution before becoming Earth’s most formidable predators.
A new relative of the Tyrannosaurus rex – albeit much smaller than the huge, ferocious dinosaur made famous in countless books and films –has been discovered and named by a Virginia Tech palaeontologist and an international team of scientists.
The newly named tyrannosauroid dinosaur – Suskityrannus hazelae – stood roughly 3 feet tall at the hip and was about 9 feet in length. That means the entire animal was only slightly longer than the just the skull of a fully grown Tyrannosaurus rex, says Sterling Nesbitt, an assistant professor with Department of Geosciences in the Virginia Tech College of Science.
In a wild twist to this discovery, Nesbitt found the fossil aged just 16 whilst a high school student participating in a dig expedition in New Mexico in 1998, led by Doug Wolfe, an author on the paper.
Nesbitt says: “Suskityrannus gives us a glimpse into the evolution of tyrannosaurs just before they take over the planet.
“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 the Triceratops, predators like Tyrannosaurus rex, and duckbill dinosaurs like Edmontosaurus.”
Suskityrannus hazelae is believed to have weighed between 45 and 90 pounds, minuscule compared to the typical weight for a full-grown Tyrannosaurus rex which is roughly 9 tons.
Its diet likely consisted of the same as its larger meat-eating counterpart, with Suskityrannus hazelae likely hunting smaller animals. This particular dinosaur was at least 3 years old at death based on an analysis of its growth from its bones.
The fossil dates back 92 million years to the Cretaceous Period, a time when some of the largest dinosaurs ever found lived.
Describing the new find, Nesbitt says: “Suskityrannus has a much more slender skull and foot than its later and larger cousins, the Tyrannosaurus rex.
“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.”
No arm fossils of either specimen were found, but partial hand claws have been discovered. And, they are quite small. As the claws were incomplete, researchers can’t be sure if the new Tyrannosaurid had two fingers or three.
Two partial skeletons were found of Suskityrannus have been found thus far. The first included a partial skull that was found in 1997 by Robert Denton–now a senior geologist with Terracon Consultants–and others in the Zuni Basin of western New Mexico.
A second, more complete specimen, was found in 1998 by Nesbitt, then a high school junior with a burgeoning interest in palaeontology, and Wolfe. James Kirkland, now of the Utah Geological Survey, who helped the pair recover the specimen, says: “Following Sterling out to see his dinosaur, I was amazed at how complete a skeleton was lying exposed at the site.”
For much of the 20 years since the fossils were uncovered, the science team did not know what they had. In fact, the team first thought they had the remains of a dromaeosaur, such as Velociraptor.
During the late 1990s, close relatives Tyrannosaurus rex simply were not known or not recognized. Since then, more distant cousins ofTyrannosaurus rex, such as Dilong paradoxus, have been found across Asia
Nesbitt says: “Essentially, we didn’t know we had a cousin of Tyrannosaurus rex for many years.”
The fossil remains were found near other dinosaurs, along with the remains of fish, turtles, mammals, lizards, and crocodylians. From 1998 until 2006, the fossils were stored at the Arizona Museum of Natural History in Mesa, Arizona. After 2006, Nesbitt brought the fossils with him through various postings as student and researcher in New York, Texas, Illinois, and now Blacksburg. He credits the find, and his interactions with the team members on the expedition, as the start of his career.
He says: “My discovery of a partial skeleton of Suskityrannus put me onto a scientific journey that has framed my career.
“I am now an assistant professor that gets to teach about Earth history.”
The name Suskityrannus hazelae is derived from “Suski,” the Zuni Native American tribe word for “coyote,” and from the Latin word ‘Tyrannus‘ meaning king and ‘hazelae‘ for Hazel Wolfe, whose support made possible many successful fossil expeditions in the Zuni Basin.
Nesbitt said permission was granted from the Zuni Tribal Council to use the word “Suski.