A controversial idea suggests the ancestors of echidnas were more like the platypus. For the first time, fossil evidence ...

A recent reanalysis of a 108-million-year-old bone challenged the consensus that echidnas and platypuses descended from a single land-bound ancestor. The aquatic life was believed to have attracted a ...

What is the molecular clock? Levels of molecular variation could be used, in principle, to estimate divergence times, serving as evolutionary "clocks" that "tick" at different rates. Subsequent ...