A palaeontologist who found a fossil while still a high school student in 1998 has discovered it is a "new" species of dinosaur related to Tyrannosaurus rex.
The fossil was uncovered by Sterling Nesbitt, now an assistant professor at Virginia Tech in the US, back when he was 16.
Named Suskityrannus hazelae, the tiny dino lived 92 million years ago during the Cretaceous Period when the largest dinosaurs walked Earth.
The fossil suggests the dinosaur was only 3ft (0.9m) tall at the hip, and about 9ft (2.7m) long from snout to tail.
It is believed to have weighed between 20-40kg, compared to a fully grown T-Rex which could weigh up to 8,100kg and stand 20ft (6m) tall and 40ft (12m) long.
The tiny T-Rex likely had much the same carnivorous diet, but due to its size probably favoured going after smaller animals.
As a teenager Dr Nesbitt had been joining in with a dig expedition in New Mexico when he found a partial skeleton of the tiny T-Rex. It was the second ever found, although this one was the more complete fossil.
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The dig was led by palaeontologist Doug Wolfe, whose wife Hazel was credited by Dr Nesbitt in the naming of the dinosaur.
For two decades researchers didn't really know what they had discovered.
"Essentially, we didn't know we had a cousin of Tyrannosaurus rex for many years," Dr Nesbitt said.
He explained that the team at first thought they had uncovered the remains of a dinosaur similar to a Velociraptor.
"Suskityrannus gives us a glimpse into the evolution of tyrannosaurs just before they take over the planet," Dr Nesbitt said.