A significant discovery has emerged from the Murchison House Station near Kalbarri, Western Australia, where a bone dating back 100 million years was excavated. This fossil, identified as the flipper bone of an ichthyosaur—a marine reptile popularly referred to as a “fish lizard”—is the youngest of its kind found in the southern hemisphere.
Researchers have dedicated considerable effort to studying this remarkable find, which offers vital insights into the ichthyosaur’s existence and eventual extinction. The paleontologist who uncovered the fossil in 1995, Dr Mikael Siversson, describes ichthyosaurs as air-breathing reptiles reminiscent of a mix between sharks and dolphins. Through rigorous analysis, scientists determined that this ichthyosaur lived between 94 and 97 million years ago, suggesting that its extinction occurred later than previously thought.
During this period, ichthyosaurs were facing a significant decline, and although they did not reach the major extinction event that eradicated many species approximately 100 million years ago, they were experiencing dire challenges. This extinction event was driven by severe global warming, with carbon dioxide levels soaring to 1500 to 2000 parts per million—far exceeding current atmospheric levels.
In refining the dating of the ichthyosaur fossil, researchers also examined a fossilised shark tooth found in the same geological layer, reinforcing the age determination. This discovery is part of a larger endeavour to catalogue all marine reptiles from the dinosaur era in Western Australia.
Dr Siversson expressed enthusiasm for future research, noting that many new species and exciting discoveries await. This find not only enhances our understanding of the ichthyosaur but also contributes to a broader narrative regarding marine reptiles during the age of dinosaurs.