Trix, Tyrannosaurus rex

THE 66-million-year-old fossilised bones of a Tyrannosaurus rex were excavated in Montana in 2013. Named Trix – after the former Dutch queen Beatrix – it is among three of the most complete T. rex skeletons to exist anywhere in the world, with between 75-80 per cent of its bone volume recovered.

There are only about 15 known specimens in total, so any tyrannosaur material found is pretty exceptional. Some of the earliest ones, for instance, only had a partial jaw. Trix is considered to be female. There is a lump just above the eye socket and it is believed that the larger the lump, the more likely the animal is female.

Trix would have eaten other dinosaurs such as Triceratops. T. rex probably didn't run very fast, only about 11mph because the femur to tibia length in the leg are very similar. Fast-running animals tend to have a much shorter femur to tibia ratio. It could have caught some of the smaller dinosaurs that didn't run very fast and would probably have scavenged and eaten dead animals too. The T. rex had a well-developed part of the brain allowing it to smell things precisely.

Many early depictions of dinosaurs were as slow and lumbering creatures on four legs. Even the Megalosaurus, a big meat-eating dinosaur, was depicted as a lizard on four legs. Because the tyrannosaurus had such short limbs at the front, there is no way it could have walked about on four legs.

Why T. rex had such short arms is one of these things that is unsolved. But it probably did have reasonably bulky muscles on those arms. They weren't just passive and useless. They may have been used to rip flesh apart once prey was killed or while scavenging the meat off another animal. T. rex had a huge head full of teeth which were very sharp and serrated which suggests it was a meat-eater. If you compare its bite to a crocodile, it would have had roughly 10 times the snapping power.

There are interesting pathologies about Trix, including some in vivo damage to bones such as fractures that may have occurred as it battled with other T. rex or during mating. There may have been injuries caused during its early development or from a birth defect. If you look closely on the skeleton, there is what could be a small bite to the lower jaw that has healed over. On the ribs there is distorted growth, probably due to a fracture when it was younger.

It may be that Scotland is the birthplace of the tyrannosaurs. I found a tailbone of a theropod dinosaur in 1996 and a tooth in 2008 on Skye that may be from primitive tyrannosaurs. That was from the Middle Jurassic period, roughly 166 million years ago. The early ancestors of tyrannosaurs could have evolved in Scotland. And then evolved much later in the US and Russia as Tyrannosaurus. Trix is from the Cretaceous period, which was around 100 million years later than the Middle Jurassic.

Interview with Dr Neil Clark, curator of palaeontology at The Hunterian in Glasgow University.

T. rex in Town is co-organised by Glasgow Museums and The Hunterian. Trix will be on show at Kelvin Hall until July 31. Visit kelvinhall.org.uk/trex