A large jaw of a predatory archosaur species from the latest Triassic of South Wales, named Zanclodon cambrensis, has long intrigued paleontologists. Could it be the oldest large theropod dinosaur? In a new study, paleontologists from the University of Bristol and the National Museum Cardiff reanalyzed the specimen based on a new 3D digital reconstruction. They confirmed first that it is indeed latest Triassic in age, most likely extracted from sandstones of the Cotham Member of the Lilstock Formation; anatomically the specimen shows features of theropod dinosaurs and likely represents a species of early neotheropod dinosaur, named Newtonsaurus cambrensis.
The two separate blocks containing the jaw impression of Newtonsaurus cambrensis. Image credit: Evans et al., doi: 10.1016/j.pgeola.2025.101142.
“This specimen has been referred to many times in scientific papers, but had yet to be successfully identified — we were not even sure whether it was dinosaur,” said Dr. Owain Evans, a paleontologist at the University of Bristol.
“It was named Zanclodon cambrensis by Edwin Tully Newton in 1899, but we knew the name Zanclodon had been abandoned as referring to a broad variety of early reptiles.”
“Therefore, we name it after Newton, calling it Newtonsaurus. It is different from all other dinosaurs from around that time, and requires a distinctive name.”
Newtonsaurus cambrensis roamed our planet around 202 million years ago (latest Triassic period).
The fossil was found at the locality of Stormy Down near Bridgend, Wales, the United Kingdom.
The specimen is the natural mould of a left jaw, showing both the interior (housed at the National Museum of Wales) and exterior surfaces (housed at the British Geological Survey)
“The natural moulds of the inner and outer faces of the jawbone show amazing detail — every groove, ridge, tooth, and even the serrations along the edges of the teeth,” said University of Bristol’s Professor Michael Benton.
“We decided to use digital photography to make a 3D model.”
“We began by surface scanning the fossil using photogrammetry.”
“Once we had our digital scan, we then inverted it — essentially giving us a digital negative of the mould.”
“It was then a simple case of fusing the two sides together and analyzing the anatomy from there.”
“The digital reconstruction we have extracted from the specimen gives a much better idea of what the original structure of the bone would have looked like.”
Now that the fossil could be studied, the team was able to use its anatomy to piece together its position in the reptile family tree — and most crucially — whether it was a dinosaur or not.
“We can now confirm that this specimen very likely belonged to a large predatory theropod dinosaur, that roamed the shores of South Wales during the latest Triassic,” Dr. Evans said.
“It has some definite unique dinosaur features in the emplacement of the teeth, and it is a theropod — a predatory, flesh-eating dinosaur.”
“Otherwise, it sits near the origins of both major divisions of Theropoda, the Coelophysoidea and the Averostra.”
“Most unexpected is the size of the animal. The preserved jawbone is 28 cm long, and that is just the front half, so originally the jawbone was 60 cm long, corresponding to a dinosaur with a body length of 5-7 m.”
“This is unusually large for a Triassic theropod, most of which were half the size or smaller.”
“These historical specimens are vitally important in paleontology and often yield new and exciting results — even if they have been sitting in collections for years,” said Dr. Cindy Howells, a paleontologist at the National Museum Cardiff.
“The Victorians were fascinated by the fossil record and prospected all across the UK for fossils.”
“On top of this, the re-description of Newtonsaurus cambrensis once again highlights the significance of Wales in paleontological research.”
“These Triassic beds are rare worldwide, and yet there are several across Wales.”
“There might very well be another dinosaur waiting to be discovered.”
The findings were published online today in the Proceedings of the Geologists’ Association.
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Owain Evans et al. Re-assessment of a large archosaur dentary from the Late Triassic of South Wales, United Kingdom. Proceedings of the Geologists’ Association, published online September 11, 2025; doi: 10.1016/j.pgeola.2025.101142
