More than half a century after first being unearthed from a Welsh quarry, four small fossil fragments have finally been assigned to a new species of dinosaur.
Researchers from London's Natural History Museum say Pendraig milnerae is the oldest meat-eating dinosaur ever discovered in the UK.
It existed over 200 million years ago, their analysis suggests.
The name Pendraig means "chief dragon" in Middle Welsh.
The animal was very likely the apex, or top, predator in its environment. That said, it wasn't exactly a giant. Think of something chicken-sized with a very long tail.
"It was a typical theropod; so, a meat-eating dinosaur that walked around on two legs, like T. rex or Velociraptor that you'll know from the movies, but much earlier in time," explained the NHM's Dr Stephan Spiekman.
This is one of those classic fossil stories.
Pendraig is described by just four, albeit beautifully preserved, bone pieces. A vertebra, elements of the pelvis and a femur. These items were originally pulled from a limestone quarry near Cowbridge in South Wales in the 1950s.
Their interesting features were occasionally discussed within the NHM, but then the fossil material somehow got lost in the vast collections of the museum, mistakenly stored with crocodilian remains.
Only recently were the bones recovered from the "wrong drawer" and recognised for their true significance.
Pendraig is really ancient. It's late Triassic in age. It could be as much as 214 million years old, putting it close to the base of dinosaur emergence.
Indeed, Pendraig would have been a fossil when the previously mentioned T. rex and Velociraptor were still strutting their stuff in the Cretaceous, just before the asteroid struck to wipe them both from the face of the Earth 66 million years ago.
"We've only got these four fragments, but the preservation is fantastic. The fossil is completely three dimensional; it's undistorted," Dr Spiekman told BBC News.
"What's so interesting and important here is that we're getting to see the very early stages of the evolution of the dinosaurs. These animals eventually came to dominate the Earth, but in the late Triassic they were only one of several groups of reptiles that were living on land."
The geological study of the British Isles tells us that during this time, what is now the Bristol Channel region of the UK was a series of islands made from much older limestone that had been folded and pushed upwards.
Pendraig would have lived somewhere across the archipelago.
How this particular specimen died, we can only speculate. But its bones were embedded in a gryke, or fissure, in the limestone. Perhaps the dino fell in; maybe it was already dead and got washed in during a flood. No-one can say for sure.
There's a bit of a puzzle related to the size of the animal, which is on the small side of what might be expected. Dr Spiekman wondered if Pendraig might be an example of dwarfism, a phenomenon you sometimes see in species that are confined to islands and their limited resources. But the analysis in this case came to no firm conclusions.
The second part of Pendraig's name - its species name - recognises an influential figure in British dinosaur science: Angela Milner, who died in August.
The former deputy keeper of palaeontology at the Natural History Museum was associated with another major theropod discovery in the 1980s - an animal called Baryonyx - and was key in helping to bring Pendraig milnerae to light again.
"It wasn't lost for very long in the collections, but it was Angela we have to thank for tracking it down. She'd remembered seeing it and went off to look through the museum's drawers. And after three or four hours she returned to say, I found it!" recalled co-author Dr Susie Maidment.
"Angela had a really influential career in UK palaeontology and was a huge loss to us here at the museum. We were some way through describing the fossil when she died, but we wanted to honour her by naming the fossil after her."
Pendraig milnerae is reported in the journal Royal Society Open Science.