Fossils found over two decades ago in Japan’s Ajimu area have been reexamined, revealing a previously unknown giant salamander species that lived 3.5 million years ago during a warmer, wetter era.
- Limnospondylus ajimuensis lived around 3.5 million years ago in Kyushu.
- It may have reached lengths of approximately 1.1 meters.
- Discovery suggests more unknown salamander species in fossil records.
What happened
In the late 1990s, scientists found three vertebrae fossils in the Ajimu area of Oita prefecture, Japan. These fossils, preserved in lake sediments about 3.5 million years old from the Pliocene epoch, initially were thought to belong to the genus Andrias, which includes today's largest amphibians. However, detailed anatomical comparisons were limited at the time.
Recently, a Kyoto University team revisited these fossils and conducted a thorough analysis comparing them to modern giant salamander skeletons. They discovered unique features on the mid trunk vertebra not seen in any known giant salamander species. This led the team to identify the fossils as a new genus and species, named Limnospondylus ajimuensis after the lake-rich environment and locality where it was found.
Why it feels good
This discovery enriches our understanding of prehistoric biodiversity and the evolutionary history of salamanders. Finding a completely new genus within a well-known family highlights the potential for many unidentified species lurking in existing fossil collections, promising fresh insights into ancient ecosystems.
It also places Japan in a more prominent role in prehistoric research, showing the region’s environment was once much warmer and more humid. This broader context helps scientists appreciate how climate shifts influenced species survival and extinction, offering valuable lessons on environmental change and biological adaptation.
What to enjoy or watch next
Enthusiasts and researchers can look forward to further studies on giant salamander fossils, particularly those assigned too quickly to known species. This research suggests that many fossils in the Northern Hemisphere may reveal new diversity upon closer examination, potentially reshaping amphibian evolutionary trees.
Moreover, awareness of the fragile status of Japan’s living giant salamanders, such as Andrias japonicus, is growing. Preservation efforts are increasingly important as these native species face challenges from habitat loss and genetic mixing with non-native species. Keeping their history alive contributes to conserving their future.