380-Million-Year-Old Antarctic Fish Reveals Clues to How Life First Walked on Land

Scientists have peered inside the 380-million-year-old skull of an Antarctic fish that was closely related to the first animals to walk on land, revealing surprising adaptations that may have facilitated one of evolution's most crucial transitions. Using advanced neutron imaging technology, researchers at Flinders University examined Koharalepis jarviki, a large predatory fish from the Devonian Period that provides new insights into how life began its momentous move from aquatic to terrestrial environments.

The fossil, discovered in Antarctica's Lashly Mountains region, represents the only known specimen of its kind and belongs to the Canowindridae family—a group of fish that once lived across East Gondwana with fossils now found in both Antarctica and Australia. These ancient fish are considered close relatives of the earliest four-limbed vertebrates that eventually evolved into land animals, making their anatomy crucial for understanding the water-to-land transition that fundamentally changed the course of life on Earth.

Research Fellow Dr. Alice Clement from Flinders University's College of Science and Engineering emphasized the fossil's significance: "This precious fossil belongs to a group called the Canowindridae which highlights the ancient links between Australia and Antarctica. It is important to study such specimens from the Devonian Age of Fishes when the waters teemed with predatory lobe-finned fish like this that are closely related to land animals (tetrapods)." The Devonian Period, often called the "Age of Fishes," was a critical time when various fish lineages experimented with different body plans and ecological strategies.

The non-destructive neutron scans revealed that Koharalepis possessed brain features similar to those found in fish species associated with the evolutionary transition from aquatic to terrestrial life. Most intriguingly, the researchers discovered adaptations specifically suited for life near the water's surface, including openings in the top of the skull for additional air intake and a specialized organ within the brain that detects light and controls circadian rhythms. These features suggest the fish was adapted for environments where access to atmospheric oxygen was advantageous.

Lead author Corinne Mensforth, a PhD candidate from the Flinders Palaeontology Lab, noted the fossil's unique preservation: "We chose to focus on Koharalepis as it is the only fossil in the entire family to preserve the internal bones of the skull, which gives us valuable insights into its braincase and neuroanatomy." Growing to about one meter in length, Koharalepis was likely an ambush predator in freshwater systems, using its advanced sensory capabilities to hunt in shallow environments where the boundary between aquatic and terrestrial worlds was becoming increasingly important for survival.