Palaeontologists from St Petersburg University and scientists from Great Britain discover the oldest intact skeleton of a tailed amphibian "superhero"

Salamanders, or tailed amphibians, are amphibious animals that look like lizards. They are believed to first appear on Earth at the end of the Triassic period, simultaneously with dinosaurs about 230 million years ago. Today, there are more than 760 of their species on the planet. Palaeontologists around the world have repeatedly found isolated bones of the most ancient representatives of these amphibians. However, the intact skeleton of the archaic salamander was found in the 1970s in Kazakhstan. These were the remains of the species Karaurus sharovi, which lived on the planet at the end of the Jurassic, i.e. about 150 million years ago.

The research findings are published in the journal Proceedings of the National Academy of Sciences. Pavel Skutschas, Professor at St Petersburg University, presented the results at the science lunch about what the University palaeontologists were engaged in.

Scientists from St Petersburg University, University College London, the University of Oxford, the National Museum of Scotland, and the London Museum of History discovered the world’s second oldest skeleton of the prehistoric tailed amphibian. The find is, palaeontologists say, at least 166 million years old. Today, it is the oldest well-preserved salamander skeleton ever found.

Amphibian fossils were discovered in Middle Jurassic deposits on the Isle of Skye in Scotland. According to Pavel Skutschas, the researchers removed the rock block with the skeleton and then analysed it using computed tomography. Pavel Skutschas is a member of the research group and Professor in the Department of Vertebrate Zoology at St Petersburg University. Based on the data obtained, the palaeontologists reconstructed each bone in 3D. As a result, the scientists established that the skeleton belongs to a salamander of a previously unknown species from the genus Marmorerpeton. This is an extinct genus, whose representatives lived in the territory of modern Great Britain about 166-168 million years ago.

Marmor means marble in Latin. The Marmorerpeton salamanders are named after the marble quarries where the first isolated remains of these amphibians were found.

Pavel Skutschas, member of the research team, Professor at St Petersburg University

‘The analysis showed that our salamander is very similar to other representatives of Marmorerpeton, yet it has several significant distinguishing features. As a result, we concluded that the find was a new, previously unknown and undescribed species,’ explained Pavel Skutschas. The scientists named it Marmorerpeton wakei in memory of David Wake, an American researcher in the biology and evolution of salamanders.

Since the new species had distinctive features, the scientists faced the question of where the animal should be on the general evolutionary tree and who were its closest relatives from the previously studied salamanders. The palaeontologists compared the features of Marmorerpeton wakei with other known prehistoric salamanders.

The comparative samples included data on: representatives of the crown group, i.e. modern salamanders and their closest ancestors; and primitive stem tailed amphibians, i.e. more archaic than the direct ancestors of modern salamanders. Information about ancient Central Asian and Siberian amphibians for research was provided by the palaeontologists from St Petersburg University, who had previously found and described these animals.

The scientists entered detailed information about each genus and species of salamanders into a special matrix in the form of a digital code. Each number in it denoted the presence, absence, or other parameters of a specific trait by which the animals were compared. The researchers used the matrix and special computer programmes to develop a new relationship tree, which provided a new view on the origin of the living tailed amphibians.

A science lunch about the innovative methods of work of St Petersburg University palaeontologists and their new discoveries was held as part of the Year of Zoology at the University. Earlier, as part of the celebration of the University’s anniversary, there was an art exhibition "200 Years of Zoology of St Petersburg University"; a scientific and historical session "Zoology at St Petersburg University: Past and Present"; and a science lunch on the latest research on invertebrates. A thematic issue of the popular science magazine "St Petersburg University" was released.

‘Incorporating a species Marmorerpeton wakei into the phylogenetic tree has changed the idea of how all salamanders were related and what the early stages of their evolution are,’ said Pavel Skutschas, Professor at St Petersburg University. ‘It turned out that some of the tailed amphibians, which were considered crown, i.e. the oldest representatives of modern salamanders, are actually more primitive and belong to the stem group.’

The data obtained by the scientists will enable us to understand in more detail the appearance and evolution of tailed amphibians. It is important to gain a deeper insight into the gaps of what we know about salamanders because these animals are superheroes in the amphibian world, said Pavel Skutschas. ‘They have real superhero powers. For example, they regenerate not only the tail and paws, but also the spinal cord, part of the brain, the lens of the eye, and internal organs. If we understand how this happens, we may learn to apply the mechanisms of regeneration,’ added the palaeontologist.

According to Pavel Skutschas, studying salamanders can enable us to understand how the first terrestrial vertebrates moved with paws, and to learn more about neoteny, i.e. the ability of some organisms to spend their whole lives in the form of a larva and give offspring at the same stage of development. In some salamanders, neoteny appears in a unique form. Amphibians, after hatching from eggs, are equally likely to stop developing at the larval stage and remain in the water or turn into an adult and go to land if the conditions in their native reservoir are no longer favourable. This is not observed in any other vertebrate animal.