When a warm March day beckons Aldo and his best friend, Jack, outdoors to their fort under the giant pine tree, stick-in-the-mud Aldo gets, well, stuck in the mud. As they dig Aldo’s sneakers out from the embankment, they unearth a humungous bone, which rock-hound Jack believes to be a dinosaur fossil from the Jurassic period.

Their hilarious quest to figure out the bone’s origin and value takes them to the nearby university, the local pawn shop, the famous dino dig site a few hours away, and finally, over spring break, to Dinosaur National Monument.

Meanwhile, Aldo discovers the Indiana Jones movies, writes a book report on Journey to the Center of the Earth, starts in on a jumbo jawbreaker, and tolerates Bee, whose newfound passion for journalism could make or break him.

This tenth installment in an A-to-Z alphabet series also includes a glossary of fun and challenging “J words,” such as juju, jocular and jinx.