When Arg told his mum he was going to Slimepot Swamp to collect brontosaurus poo, she frowned. Arg didn't know if it was a good frown or a bad frown. Sometimes it was hard to tell what his mum was thinking. Stone Age people always looked like they were frowning. Even when they weren't. And Arg's mum was frownier than most. Arg's dad said that's why he dragged her into his cave ...When Arg told his mum he was going to Slimepot Swamp to collect brontosaurus poo, she frowned. Arg didn't know if it was a good frown or a bad frown. Sometimes it was hard to tell what his mum was thinking. Stone Age people always looked like they were frowning. Even when they weren't. And Arg's mum was frownier than most. Arg's dad said that's why he dragged her into his cave ...