Researchers have discovered the 90-million-year-old skeletal remains of a horse-sized dinosaur that is believed to be the missing piece that would complete the family tree of the fearsome tyrannosaurus rex.

In a study featured in the journal Proceedings of the National Academy of Sciences, researchers from various scientific organizations, including the University of Edinburgh in the United Kingdom and the Smithsonian National Museum of Natural History in the United States, describe a set of dinosaur bones they found in a desert in Uzbekistan.

The creature, which has been given the name Timurlengia euotica, showed characteristics that were similar to an earlier and a much smaller species of tyrannosaurus known as tyrannosauroids. However, the advanced ears and large brain outlined on the dinosaur's skull fragment suggest that it may have also shared traits with a later and much larger species, the tyrannosaurus rex.

The team believes the Timurlengia euotica may very well hold the key to the secret of how the tyrannosaurus was able to grow so big.

Evolution Of The Tyrannosaurus

Scientists estimate that the first tyrannosaurs came into existence about 170 million years ago. Some of the early tyrannosauroids were merely the size of dogs.

However, about 80 million years ago during the latter part of the Cretaceous Period, one species of tyrannosauroids, the tyrannosaurus rex, evolved into a large and menacing land predator.

This creature had massive heads and very powerful jaws that produce a bite force of about 13,000 pounds. It can also grow to become as big as a full-sized bus.

Tyrannosaurus rex was not only one of the largest creatures of its time, but it was a very capable hunter as well.

Hans-Dieter Sues, a researcher from the Smithsonian National Museum and one of the authors of the study, said that contrary to what many people thought about the tyrannosaurus rex from the first "Jurassic Park" film, the creature was gifted with a keen sense of smell, hearing and even eyesight.

The tyrannosaurus rex's killer instincts come from its two grapefruit-sized olfactory lobes that allowed it to smell objects very acutely. Its long, looped ear canals, on the other hand, allowed it to hear even low-frequency sounds generated by the footsteps of their prey from a distance.

"It was sort of a superpredator," Sues pointed out.

Finding out exactly how tyrannosaurs became quite the gifted predators, however, remained an elusive achievement for paleontologists over the years. This was because they did not have enough data on 100-million-year-old fossil records that pertain to the earlier and smaller tyrannosauroids.

Discovery Of The Timurlengia Euotica

With the dissolution of the Soviet Union, researchers from different parts of the world now had access to territories where tyrannosauroids remains could be found.

In 2004, a team of scientists unearthed a braincase fragment that was believed to be owned by some sort of dinosaur. It was kept in storage at the Zoological Institute of the Russian Academy of Sciences, until one of the members of the current research team, Steve Brusatte, came across the bone fragment in 2014.

Brusatte and his colleagues made use of CT scans in order to better understand the structure of the braincase fragment. They discovered that the Timurlengia euotica had elongated inner ear canals, much like those seen on the tyrannosaurus rex. These would have given the creature an acute sense of hearing.

The size of the braincase fragment, however, showed that the Timurlengia euotica lacked the knobs and recesses that a tyrannosaurus rex would likely have. This means that the Timurlengia also shared some physical similarities with the earlier tyrannosaur known as Xiongguanlong.

The researchers believe that tyrannosaurs were able to develop their brain structure and keen hunting senses first before they became gigantic creatures. Their smarts for hunting prey made them more than capable of becoming the apex predators of their time.

Photo: Alan Wu | Flickr