TYRANNOSAURUS MATH, a close relative of Tyrannosaurus rex, lived in the late Cretaceous Period, 65 to 68 million years ago, in Western North America. He and his siblings were eleven to fourteen feet tall, weighed five to seven tons, had two-and-a-half foot long arms, two-and-a-half foot long feet, and teeth that were ten inches long! MICHELLE MARKEL, the author of five children's books, has also written for national newspapers and taught in elementary schools. Tyrannosaurus Math grew out of an experience in the classroom: "One day I was teaching math to second graders. Knowing how kids loathe word problems, I invented some of my own, using dinosaurs. The kids loved them." The rest is prehistory. Michelle lives near Los Angeles. DOUG CUSHMAN, a Northern Californian now living in Paris, has written and/or illustrated more than one hundred children's books.

In high school, Doug created comic books lampooning his teachers, and he sold them to classmates for five cents a piece.