This prehistoric fish may explain how animals first walked on Earth

Researchers at Flinders University have uncovered new details about one of the ancient fish species closely related to the first animals that eventually made the transition from water to land more than 380 million years ago. Using advanced neutron imaging technology, scientists examined the skull and braincase of Koharalepis jarviki , a large predatory fish that lived during the Devonian Period, often called the "Age of Fishes." The fossil was discovered in Antarctica's Lashly Mountains region a

"This precious fossil belongs to a group called the Canowindridae which highlights the ancient links between Australia and Antarctica," says Flinders University Research Fellow Dr. Alice Clement, coauthor of a new article in Frontiers in Ecology and Evolution . "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)," says Dr. Clement, from the College of Science and Engineering. Koharalepis belonged to the Canowindrid family, a group of fish that once lived across East Gondwana, with fossils now found in both Antarctica and Australia. Scientists consider these fish to be close relatives of the earliest four-limbed vertebrates that later evolved into land animals. Lead author Corinne Mensforth, a PhD candidate from the Flinders Palaeontology Lab, says the fossil is especially valuable because it preserves the internal bones of the skull. "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." The scans revealed that the fish's brain shared similarities with species associated with the evolutionary transition from aquatic to terrestrial life. "We found evidence that the brain of Koharalepis was similar to those of the fishes that straddle the vertebrate water-to-land transition. "We also found adaptations to life near the surface of the water, including openings in the top of the skull for additional air intake and an organ within the brain that detects light and circadian rhythms." The researchers believe these features may have helped the animal survive in shallow environments where access to oxygen near the water's surface was important. The study also sheds light on how Koharalepis may have behaved in its environment. Growing to around 1 meter in length, the fish was likely an ambush predator that hunted smaller animals in freshwater systems.

Key points

• "This precious fossil belongs to a group called the Canowindridae which highlights the ancient links between Australia and Antarctica," says Flinders University Research Fellow Dr.
• Alice Clement, coauthor of a new article in Frontiers in Ecology and Evolution .
• "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)," says…
• Clement, from the College of Science and Engineering.
• Koharalepis belonged to the Canowindrid family, a group of fish that once lived across East Gondwana, with fossils now found in both Antarctica and Australia.