Letter: When the birds got their bird-like hip joints

From Georgina Skipper, Weymouth, Dorset, UK

The article on dinosaur taxonomy was very interesting (5 May, p 38). Can you explain why the sparrow is deemed to have non-bird-like hips? Do the other birds know?

The editor writes:
• We're so glad you asked. We used sparrows to illustrate all birds, which belong to a branch of lizard-hipped dinosaurs that later evolved bird-like hips – in a classic case of convergent evolution.