A new species of feisty amphibian that lived in the shadows of dinosaurs has been discovered by a researcher at the University of Portsmouth.
The discovery fills a gap in the evolutionary history of a now extinct group, the albanerpetontids.
Wesserpeton, nicknamed ‘Wessie’, was tiny, about the size of a small, modern-day newt. Unlike most amphibians, albanerpetontids had a scaly skin and eyelids showing that they spent most of their time on land. Details of the skeleton also suggest that they were well adapted to burrowing.
The creature lived on the Isle of Wight, often called Dinosaur Island, about 130 million years ago during the Early Cretaceous, at the same time as dinosaurs such as Neovenator, Iguanodon and giant, long-necked sauropods.
Broken but healed jaws among the bones suggest Wessie was a fiesty creature. Like some modern-day salamanders it probably engaged in fierce battles for mates and territory, and sharp chisel-like teeth indicate that it was a predator.
Lead researcher, Dr Steve Sweetman, said: “When I started looking for the little animals that lived with the dinosaurs a Wessie jaw was the first thing I found and I can still remember how excited I was. I also remember thinking that ‘albanerpetontid’ was a heck of a mouthful for such a tiny creature.
“Of the 50 or so new four legged animals I have now found, Wessie bones are the most common and it was clearly well adapted to the ancient floodplain environment in which it lived.”
The researchers have no complete skeletons of Wessie but they have a large number of isolated bones representing almost all parts of the animal.
Dr Sweetman and his co-author, Dr Jim Gardner of the Royal Tyrrell Museum of Palaeontology, Canada, named the animal Wesserpeton because its bones come from rocks known as the Wessex Formation.
Dr Sweetman said: “It is a pure coincidence that the nickname rhymes with another well-known monster.”
The discovery of Wessie neatly fills an evolutionary gap. Albanerpetontids are first found in rocks of Middle Jurassic age and their last occurrence is in the Late Pliocene. During this period of more than 165 million years, skull bones known as frontals gradually changed from bell-shaped to triangular. Until now, part of this transition was missing from the fossil record.
Dr Sweetman said: “Until the discovery of Wesserpeton there appeared to be an abrupt transition from the more primitive elongated and bell-shaped frontals of the early albanerpetontids to the triangle shaped frontals of later forms. The frontals of Wesserpeton are elongated but they are also triangular, neatly filling the gap between the two.”
Palaeoherpetologist and albanerpetontid specialist Dr Jim Gardner from the Royal Tyrrell Museum of Palaeontology travelled to the UK to work on the project and Dr Steve Sweetman from the University of Portsmouth’s School of Earth and Environmental Sciences made the journey in the opposite direction to work on material held in the Royal Tyrrell’s collections.
The Wessex Formation is unique as it contains plant debris beds of a type so far not recorded anywhere else in the world. Decaying plant material in the sediment removed oxygen and provided ideal conditions for the preservation of bones.
Dr Sweetman said: “From the plant debris beds we have bones of some of the largest creatures to have walked the earth during the Early Cretaceous mixed with those of some of the smallest, including those of Wessie. This is really quite remarkable and it is what makes the dinosaur-bearing rocks of the Isle of Wight so special.”
The discovery is published online in the journal Acta Palaeontologica Polonica.