From Russell Barlow
Your article on the lizard that digs the deepest nest in the vertebrate world (4 July, p 16) reminded me of an episode of the BBC’s Walking with Monsters. It showed a diictodon of the late Permian with a spiral nest about 1.5 metres deep.
So the spiral is not a recent invention. It allows an extended entrance within a small soil area, to help maintain the environment of the nest chamber.
I was comforted in two ways by this article. It confirms that nature knows better than to mess with a good idea, even after 250 million years; and it shows that we do not know everything.
Stafford, UK
