Listener Tim got in touch to ask: Why do the poles go north-south as opposed to east-west? Graihagh Jackson spoke to Imperial College's Stuart Higgins to find out... Like this podcast? Please help us by <a href="https://www.thenakedscientists.com/donate">supporting the Naked Scientists</a>

How did birds survive the dinosaur mass extinction?

Each week we set out to solve one of the world's weirdest, wackiest, funniest and funkiest scientific puzzles. And along with the answer there's a brand new question to think about for next time...