T-Rex's three foot tall relative

10 May 2019

Suskityrannus hazelae NOT FOR RE-USE

An artist's rendering of how Suskityrannus hazelae may have looked.

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Meet T-Rex's pint-sized ancestor, revealed after twenty years hidden away...

You’ve probably heard of Tyrannosaurus rex: the twenty-foot-tall monsters that ruled the earth millions of years ago. But you probably haven’t heard of their miniature ancestors.

A team of palaeontologists have just described a new dinosaur, a carnivore called Suskityrannus hazelae. This evolutionary cousin to the T-Rex looks similar to it, but an adult Suskityrannus stood only three to six feet tall.

It also fills in a missing link in dinosaur evolution. We don’t have many fossils of predators from the time when Suskityrannus lived, so it gives a hint into how some of the most iconic dinosaurs like T-Rex or Triceratops grew to be so big.

What’s unusual is that it’s taken more than twenty years to describe the creature. Robert Denton, an expedition leader for the Zuni Basin Paleontological Project, found part of its skull in New Mexico in 1997. Then, the next year, his team invited a sixteen-year-old student called Sterling Nesbitt to join them out in the basin. Nesbitt found the second fossil, an almost complete skeleton.

At the time, the team had no idea what this animal was - they only knew it was some sort of three-foot-tall carnivore from around 92 million years ago. Nothing like it had been found before. Nesbitt said he took his fossil with him around different universities as he followed a career in research. “It was always in the back of my head.”

Since finding the fossils, a number of similar dinosaurs called tyrannosauroids have been discovered in China. The Chinese creatures are smaller, and date from millions of years earlier than Suskityrannus - suggesting that as these tyrannosauroids evolved, they got larger, until eventually reaching T-Rex’s size.

Today Nesbitt is an assistant professor in geosciences at Virginia Tech. Last summer, he finally decided there was enough information to classify Suskityrannus. He called up his old paleontological team, and together they described it, had it illustrated, and named it. ‘Suski’ means ‘coyote’ in the Native American Zuni language; ‘tyrannus’ is latin for ‘king’; and ‘hazelae’ refers to Hazel Wolfe, the wife of Nesbitt’s supervisor when he found the fossil.

Suskityrannus hazelae is the most complete skeleton of a predatory dinosaur that we have from the time - a period 92 million years ago called the Middle Turonian, where there was a big rise in sea level. There are very few fossils from the Middle Turonian, so this one fills an important gap.

Suskityrannus helps to pin down the evolutionary timeline of how dinosaurs grew to massive sizes 25 million years later, just before they went extinct. It also sheds light on the evolution of certain features, like a unique foot design that some therapod dinosaurs used for running.

After more than two decades, Nesbitt’s discovery has finally been shown to the world. To him, this miniature T-Rex has framed his journey through science. “This is the end of the beginning of my career.”

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