Home » Ancient salamander fossil discovered in Scotland after 45 years

Ancient salamander fossil discovered in Scotland after 45 years

by News Staff

In the enchanting landscape of the Isle of Skye, nestled off the north-west coast of Scotland, an extraordinary discovery emerged from the ancient depths of Jurassic limestones: the skull of one of the most ancient salamanders ever unearthed. However, it would be several decades before scientists could piece together this remarkable salamander’s story, hindered by technological and funding constraints.

The initial chapter of this tale unfolded in the early 1970s when paleontologists Michael Waldman and Robert Savage noticed a peculiar sight - black bone peeking out from the unyielding gray rock, hinting at a hidden fossil treasure. Recognizing its potential significance, they collected the find, but the portions of the fossil revealed at the time were insufficient to justify a comprehensive study. Consequently, the fossil remained entwined in the rock, unexplored, for another 45 years.

The story took a turn in 2004 when field expeditions to the site resumed, unearthing various fossils, including elusive salamanders. Roger Benson, a seasoned paleontologist, took a closer look at the block collected in the 1970s and made a connection - the broken surface mirrored a specimen he had collected in 2016.

In the realm of paleontology, most collected bones don’t receive immediate attention. Acquiring funds for fieldwork is challenging, and securing resources for the subsequent fossil study is an even greater obstacle. Consequently, many specimens remain dormant and unstudied for decades.

It was only through the lens of X-ray microCT scanning that the secrets held within the rock were unveiled - a new fossil species of salamander, christened Mamorerpeton wakei, emerged. At a staggering age of 166 million years, it stands as one of the oldest-known salamanders, providing a remarkable window into the earliest stages of their evolutionary journey.

Salamander fossils, in the grand tapestry of paleontology, are a rare find. Throughout the entire Jurassic period, spanning from 201 to 145 million years ago, fewer than 20 species have come to light. In stark contrast, we have documented over 450 dinosaur species. The scarcity of salamander fossils may be attributed to their petite and fragile nature, but it also reflects the historical lack of scientific attention they have received.

Image of digital bones within a transparent digital model of the rock (Specimen NMS G.1992.47.9 which comprises three blocks). Credit: Elizabeth Griffiths, Lucy Hill, Roger Benson, Marc Jones

Recognition at last

Three decades ago, the first tantalizing hints of an extinct salamander species emerged when fossilized backbone and jaw bones were discovered near Oxford, England. Oddly, this find was largely overlooked by the scientific community, overshadowed by the allure of researching the Karaurus salamander from the Middle Jurassic period, which had often been hailed as the common ancestor of modern salamanders.

The fossilized bones of Mamorerpeton remained shrouded within unforgiving rock, their true contents concealed until the advent of X-ray microCT scanning. Many of the blocks collected in the field held secrets unknown to the researchers at the time. Astonishingly, a fossil block retrieved in 2016 turned out to be the missing piece of a specimen collected over four decades earlier from the same location.

This discovery, which included an exceptionally well-preserved skeleton with the skull and tail intact, ushered in an intricate process of transforming bones into digital models. The painstaking effort led to the creation of an unprecedented three-dimensional model of the salamander’s skull.

In the realm of paleontology, it’s not uncommon for fossils to languish unexamined for years due to constraints in time and expertise. The 1971 specimen, for instance, revealed only the edges of some bones, making their extraction a daunting challenge. Mechanical removal posed a risk of damage, but X-ray microCT scanning brought clarity to the situation.

Upon in-depth analysis, this newly unearthed species, Marmorerpeton, was positioned within the extinct Karauridae group. Members of this group were distinguished by skull bones adorned with crocodile-like features and bony projections behind the eyes. In honor of the late Professor David Wake, an esteemed authority on salamander evolution, the new species received its name.

The salamander’s distinctive features, including its wide skull, deep tail, and limb bones with unfinished ends, hinted at an aquatic lifestyle similar to the North American hellbender salamander (Cryptobranchus) and the giant salamander of China and Japan (Andrias). It is likely that Marmorerpeton subsisted on insects through suction feeding and laid externally fertilized eggs.

Salamanders typically fall into one of three categories: aquatic, terrestrial, or they begin as aquatic and transition to land-based life in adulthood. While it’s plausible that the earliest salamanders were exclusively aquatic, the dearth of fossils leaves room for uncertainty.

This groundbreaking study challenges established notions of salamander evolution, suggesting that several fossils from China, previously thought to be early members of modern salamander groups, are not closely related to present-day salamanders. The overreliance on Karaurus, often dubbed the “Archaeopteryx of salamanders,” from the Late Jurassic of Kazakhstan, has been called into question.

Simplified evolutionary tree of amphibians showing how Marmorerpeton is probably related to other salamanders. Ma = millions of years ago. Credit: Silhouettes are from Phylopic.org and originals by Marc Jones
Modern salamander diversity. Top row: Amphiuma; Bolitoglossa; Andrias; Middle row: Necturus; Plethodon; Desmognathus; Bottom row: Triturus; Eurycea; Salamandr. Credit: See individual images.

Salamanders today

Salamanders play a pivotal role in the world of science, serving as a wellspring of knowledge for understanding various aspects of life. Researchers have delved into the mysteries of salamanders to gain insights into skeletal development, limb and organ regeneration, and toxicology across all vertebrates. Surprisingly, despite their significance, salamanders remain shrouded in relative obscurity for many people, who often mistake them for lizards and underestimate their incredible diversity.

Presently, there are over 750 salamander species scattered across the northern continents. Within this diverse family, one can encounter eel-like forms dwelling in submerged caves, aquatic herbivores sporting beak-like mouths, and small land-dwelling salamanders that exhibit remarkable climbing abilities, using their tails. Some even employ chameleon-like tongues to capture their prey. What’s more, several salamander species demonstrate intriguing parental care behaviors, including nest preparation and vigilant guarding.

In the United Kingdom, a trio of salamander species calls it home. These creatures spend their juvenile stages in the water, often referred to as newts, before transitioning to a land-based lifestyle as adults. They make a poignant return to the aquatic realm when it’s time to breed. Salamanders hold a crucial position in various food webs, as they have a hearty appetite for insects, and they, in turn, become prey for a multitude of animals, and even certain plants. However, the shadow of habitat loss looms over many salamander species, putting them at risk.

The Middle Jurassic fossil sites on Skye stand as global treasures in the field of paleontology. These locations have yielded a rich tapestry of ancient life, including fossils of lizard-like reptiles, early lizards, crocodylomorphs, turtles, pterosaurs, mammaliaforms, and long-necked dinosaurs. The historical significance of Skye’s fossils extends far beyond the realm of salamanders, offering a window into the fascinating diversity of prehistoric life.

Source: The Conversation

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