The combination of hide-and-seek and sliders to manipulate with fanciful dinosaurs should guarantee an audience for this board book. Beginning with the front cover, a smiling green dinosaur is hiding in plain sight in every picture: in a window, behind a sofa, in the shower, in bed, in the freezer. On each page the titular refrain is repeated, followed by a question that hints at where the dinosaur will be found. It doesn't hurt success that the dinosaur doesn't really fit in its hiding places. Toddlers will quickly find the clearly marked slider that confirms their guess, sliding the head of one out from behind the sofa or pulling back the shower curtain to reveal another. The book ends with a final affirmation: "I knew I saw a dinosaur. There it is!" The slider on that page makes the dinosaur's head nod up and down. The format is repeated in the companion volume, I Thought I Saw a Lion, with the lion hiding in a restaurant, costume shop, library, and beauty shop. Digitally produced drawings in a retro palette are reminiscent of mid-20th-century printmaking and folk art. Except for a brown-skinned waiter and a brown-skinned customer getting her straight brown hair cut in the beauty parlor in Lion, the people in both books are white. Unfortunately, the sliders have a tendency to become quite loose after repeat readings and slide when the book is merely tilted.The minor flaw in the construction makes this a nonessential purchase for all but the most dino-happy tots. (Board book. 2-3)