Michael Morris 
The Amazing Imagination of Joshua [EPUB ebook] 

One day, I came home from work, and my son was at the dinner table playing with his toy dinosaurs. As I settled in on the couch to watch TV, I noticed how much fun he was having and wanted to play too. I sat down at the table with him and began to explain to me what he was doing. He told me how he was making his two favorite T. rex dinosaurs arm wrestle. He explained to me how the smaller one was the arm wrestling champ because he was so small that he has the most power. That’s how the story was born.