This prehistoric fish may explain how animals first walked on Earth

Scientists have examined the skull of Koharalepis jarviki, a 380-million-year-old prehistoric fish closely related to the earliest animals that transitioned from water to land. Using advanced neutron imaging, researchers at Flinders University studied the fossil, discovered in Antarctica’s Lashly Mountains, revealing internal skull structures that provide new insights into the evolutionary steps leading to terrestrial life. The findings highlight adaptations suited for surface-dwelling, such as skull openings potentially used for gulping air and a light-sensitive brain organ linked to day-night cycles. Koharalepis jarviki belonged to the Canowindridae family, a group of predatory lobe-finned fish that lived during the Devonian Period, often called the "Age of Fishes." Fossils of this family have been found across East Gondwana, including Antarctica and Australia, underscoring ancient biogeographical connections. The preservation of internal skull bones in this specimen is unique, allowing researchers to analyze its braincase and neuroanatomy in unprecedented detail. This has provided valuable clues about the evolutionary transition from aquatic to terrestrial vertebrates. The study revealed that Koharalepis possessed brain features similar to those of species known to bridge the gap between water and land life. The presence of skull openings suggests adaptations for breathing air, while the detection of a light-sensitive organ indicates an ability to regulate circadian rhythms, important for surface or shallow-water living. These traits offer important evidence about how early vertebrates might have coped with environmental challenges during the move onto land. This research enhances understanding of the complex evolutionary processes that enabled vertebrates to colonize terrestrial habitats. By shedding light on the anatomy and lifestyle of a key Devonian fish, the findings contribute to broader knowledge of vertebrate origins and the biological innovations that paved the way for life on land.