The fearsome Tyrannosaurus Rex is often referred to as the ‘King of the Dinosaurs’.
But what came before it and how did it evolve to become the terrifying beast that it did?
Palaeontologists now think they are closer to having the answer after discovering the remains of a ‘frightful’ new species of tyrannosaur with horns around its eyes.
They think that Daspletosaurus wilsoni, which was identified by fossilised skull and skeletal fragments that date to about 76.5 million years ago, could have been a director ancestor of T.Rex.
Meet the ‘frightful’ one: Palaeontologists have discovered a new type of tyrannosaur with horns around its eyes. Daspletosaurus wilsoni (shown in an artist’s impression) was identified by fossilised skull and skeletal fragments that date to about 76.5 million years ago
Palaeontologists from the Badlands Dinosaur Museum in North Dakota uncovered the fossils, which include a rib and toe bone, at the Judith River Formation, in northeastern Montana, between 2017 and 2021
The new species was found in Montana and is seen as a ‘half way point’ or ‘missing link’ between older and younger tyrannosaur species.
It has a mix of features found in more primitive tyrannosaurs from older rocks, such as a prominent set of horns around the eye, as well as features otherwise known from later members of this group (including T. rex), like a tall eye socket and expanded air-pockets in the skull.
The genus Daspletosaurus is Greek for ‘frightful lizard’.
Palaeontologists from the Badlands Dinosaur Museum in North Dakota uncovered the fossils, which include a rib and toe bone, at the Judith River Formation, in northeastern Montana, between 2017 and 2021.
The original discovery was made by crew member Jack Wilson, who spotted a small flat piece of bone projecting out from the bottom of a towering cliff.
This distinctive flat bone was the middle part of the nostril of a tyrannosaur and careful digging around the bone revealed a complete premaxilla – the bone at the tip of the snout.
The new species was found in Montana and is seen as a ‘half way point’ or ‘missing link’ between older and younger tyrannosaur species
The new specimen is one of four tyrannosaur skeletons recently collected by Badlands Dinosaur Museum. This images depicts the four disputing ownership of the fresh carcass of a Centrosaurus
The new species has a mix of features found in more primitive tyrannosaurs from older rocks, such as a prominent set of horns around the eye, as well as features otherwise known from later members of this group, like a tall eye socket and expanded air-pockets in the skull
A few broken vertebrae from around the site showed that this was a large tyrannosaur, but there was 25ft (8m) of rock on top of the bones
The researchers think that D. wilsoni was the descendant of Daspletosaurus torosus and the predecessor of Daspletosaurus horneri, which likely emerged between 77 and 75 million years ago
WHAT WAS T. REX?
Tyrannosaurus rex was a species of bird-like, meat-eating dinosaur.
It lived between 68–66 million years ago in what is now the western side of North America.
They could reach up to 40 feet (12 metres) long and 12 feet (4 metres) tall.
More than 50 fossilised specimens of T. Rex have been collected to date.
The monstrous animal had one of the strongest bites in the animal kingdom.
An artist’s impression of T. Rex
A few broken vertebrae from around the site showed that this was a large tyrannosaur, but there was 25ft (8m) of rock on top of the bones.
In 2020 and 2021, palaeontologists used a jackhammer to dig down to the bone layer whereupon they discovered a partial skull and skeleton.
The specimen was nicknamed ‘Sisyphus’ in recognition of the enormous effort required to remove the surrounding rock.
Sisyphus is a figure from Greek mythology who, after cheating death twice, was forced by Hades, the god of death, to repeatedly roll a boulder up a mountain for eternity.
The researchers think that D. wilsoni was the descendant of Daspletosaurus torosus and the predecessor of Daspletosaurus horneri, which likely emerged between 77 and 75 million years ago.
They say the anatomy of their new discovery supports the theory that the Daspletosaurus lineage is ancestral to T. rex.
All three daspletosaur species belong to the family Tyrannosauridae, which includes nine genera, including Tyrannosaurus.
‘Many researchers disagree as to whether tyrannosaurids represent a single lineage evolving in place, or several closely related species that do not descend from one another,’ said study co-authors Elías Warshaw and Denver Fowler.
This has been hindered by a lack of high-quality specimens to examine, they added.
But the discovery of Daspletosaurus wilsoni suggests that the three daspletosaurs came one after the other, like ‘consecutive ladder-like steps in a single evolutionary lineage,’ the researchers wrote, rather than branching off from one another like ‘evolutionary cousins’.
The findings suggest that previous research was correct in identifying several species of Daspletosaurus as a single evolving lineage, and supports the descent of T. rex from this group.
The discovery was revealed in the journal Paleontology and Evolutionary Science.
The original discovery was made in by crew member Jack Wilson, who spotted a small flat piece of bone projecting out from the bottom of a towering cliff
This spine from the middle of the back was one of the first bones found at the site in 2017
The skull bones are very finely preserved. Here you can see a closeup of the pits and grooves on the side of the upper jaw. These would have housed blood vessels and sensitive nerves
Study co-author Dr Denver Fowler is pictured posing with the upper jaw found in the quarry