From Mary Voice, Melbourne, Australia
Your report on rethinking when kangaroos first hopped made me recall a question I have long pondered (16 February, p 20). Members of the kangaroo family exhibit magnificent racing and jumping ability due to their long hind leg tendons, elasticity of stride and counterbalancing tail, with smaller but useful front paws.
Many dinosaurs appeared to have the beginnings of similar traits. They mainly walked on hind legs with counterbalancing tails. But they seem to have continued to lumber along for tens of millions of years. Maybe it was just bad luck that they didn’t evolve the grace and efficiency of the kangaroo. But it would be great to hear the views of evolutionary biologists who may have pondered the same question.
