Ancient footprints in Australia challenge timeline of reptile evolution

In Australia, researchers announced a groundbreaking discovery of fossilized footprints belonging to a primitive reptile, found on a 356 million-year-old slab of rock. These findings suggest that the origins of reptile ancestors and the amniote lineage are significantly older than previously believed, dating back approximately 35 to 40 million years earlier than existing evidence indicated. These ancient tracks also prompt a reevaluation of the evolutionary timeline for tetrapods transitioning from aquatic to terrestrial life. The discovery had immediate implications for our understanding of the amniote group, which includes reptiles, birds, and mammals. Previously, the earliest recognized body fossils and associated footprints of amniotes were dated to around 318 million years ago. The new evidence indicates that these crucial evolutionary stages likely occurred much more rapidly, signaling a sophisticated level of diversity among tetrapods at that time. Researchers led by John Long, a strategic professor in paleontology at Flinders University, assert that this finding compels a reinterpretation of established notions regarding amniote evolution and its diversification. The fossil footprint slab, which was easily manageable for an individual to lift, was discovered in the Mansfield district, where Long has been studying ancient fish fossils since 1980. The researchers noted that the footprint design bears similarity to that of a modern water monitor, suggesting the animal may have been comparable in size to a small goanna-like creature. Insights drawn from this discovery imply that the evolutionary divergence between the two main lines leading to modern tetrapods occurred earlier than previously understood, potentially during the Devonian Period, around 380 million years ago. Such findings are crucial for understanding the evolution of life on Earth, particularly the pivotal shift from marine to terrestrial habitats. This research not only reveals a richness of diverse tetrapod species existing concurrently but also opens up new avenues for fossil exploration. The authors recommend extending fossil-search efforts into areas that previously formed part of the southern supercontinent Gondwana, which incorporated regions that are now Africa, South America, Arabia, Madagascar, Antarctica, and India. The implications of this discovery may significantly enhance our understanding of the evolutionary history of various life forms, contributing vital knowledge to the saga of life’s transition onto land.