A new fossil discovery is upending long-held assumptions about how vertebrates first colonized land. Palaeontologists report that the early ancestors of amphibians, reptiles, and mammals did not pass through a larval stage with external gills, as modern frogs and salamanders do.
The findings directly challenge the traditional view that the first land animals underwent a fish-like metamorphosis. Instead, these early tetrapods appear to have developed more directly into terrestrial forms, suggesting a far more rapid evolutionary shift than previously imagined.
Details of the fossils, described by researchers at New Scientist, reveal anatomical features inconsistent with an aquatic larval phase. The evidence points to a developmental pathway that bypassed external gills entirely, though specific counts or percentages of species affected were not provided in the available material.
If confirmed, this discovery would rewrite the textbook narrative of how animals conquered land. It implies that the evolutionary pressures driving the water-to-land transition were more complex and potentially more urgent than assumed, possibly tied to changing environments or competition.
Some experts caution that the fossil record remains fragmentary, and the sample may not represent the full diversity of early tetrapod development. Broader sampling is needed before conclusions can be drawn.