Little Grunt and the Big Egg — Tomie DePaola

Tomie dePaola's classic (and hilarious) story of a young cave boy and his mysterious egg.
Mama Grunt sends Little Grunt out to find a dozen eggs. All he can find is one huge egg. The egg hatches and out pops a baby dinosaur. Little Grunt names him George. Soon George grows too big for the Grunt family cave, and poor Little Grunt has to send him away. But when the local volcano erupts, there's only one dinosaur who can save the day!