Oldest theropod dinosaur in the UK discovered in southern Wales

Scientists from the Natural History Museum and the University of Birmingham have described a new species of dinosaur from specimens found in a quarry in Pant-y-ffynnon in southern Wales.

Following on from a new species of ankylosaur, Pendraig milnerae marks the second new species of dinosaur described by Museum scientists in the last few weeks.

The new dinosaur is a theropod, a group which also includes T. rex and modern birds. Pendraig milnerae is the earliest example of a theropod found in the UK so far, living between 200 and 215 million years ago during the Late Triassic period. It likely had a body size around that of a modern-day chicken and would have been a metre long including its tail.

The fragmentary fossils of the species consist of an articulated pelvic girdle, sacrum and posterior dorsal vertebrae, and an associated left femur, and by two referred specimens, comprising an isolated dorsal vertebra and a partial left ischium.

Dr Stephan Spiekman, Research Fellow at the Natural History Museum and first author on the paper, said: ‘Pendraig milnerae lived near the beginning of the evolution of the meat-eating dinosaurs. It’s clear from the bones we have that it was a meat-eater, but early in the evolution of this group these animals were quite small, in contrast to the very famous meat-eating dinosaurs like T. rex which evolved much later.’

Dr Spiekman and his colleagues described the species and named it Pendraig milnerae: Pendraig meaning ‘Chief Dragon’ in Middle Welsh, a reference to the species’ likely position as an apex predator of the area and its discovery in Wales, and milnerae honouring Dr Angela Milner, who passed away on 13 August 2021 and who was instrumental in relocating the specimen, as well as contributing significantly to our understanding of theropod dinosaurs from the UK.

Dr Susannah Maidment, a Senior Researcher in paleobiology at the Museum who worked with Angela, says, 'I told Angela that I couldn't find the specimen, and so she went away and about three hours later she had it.

'She found it in a drawer with crocodile material.  She must have had the specimen in her mind's eye from when she had previously looked through that drawer. This paper would not have been possible without her.

'Angela was really important in the Museum for many years, she was not only the premier dinosaur researcher but also in a senior administrative position as Deputy Keeper of Palaeontology when women didn't generally occupy such roles in the Museum, so for me as a student it was really important.

'She really inspired me and was incredibly helpful when I joined the Museum. She went out of her way to show me the ropes, and that goes for me and so many others, including three of the authors of this paper.'

The discovery of this new species could also provide evidence for potential island dwarfism among species in the area, but this is not currently conclusive.

‘The area where these specimens were found was most likely an island during the time period in which it lived,’ explains Dr Spiekman. ‘Species which live on islands often tend to become smaller than those on the mainland in a phenomenon called island dwarfism.

‘Because the fossil reptiles from this area, including Pendraig, are all quite small-sized, we used statistical analyses to investigate whether Pendraig might have been an insular dwarf. The results indicate that Pendraig is indeed small, even for a theropod of that time period, but not uniquely so.

‘Furthermore, based on several characters on the bones, we were able to determine that, although the specimens of Pendraig were not very young, they were also likely not fully grown. So Pendraig might have gotten somewhat bigger than the specimens we have so far, which limits our ability to perform reliable body size analyses.

‘With this in mind, we need more evidence from more species to investigate the potential for island dwarfism in this area during that time, but if we could prove it, it would be the earliest known occurrence of this evolutionary phenomenon.’

The study Pendraig milnerae, a new small-sized coelophysoid theropod from the Late Triassic of Wales is published in Royal Society Open Science.