12" Wooden Ruler made in U.S.A. of American-grown basswood.
The Mesozoic Era lasted for something like 186 million years, from 252 to 66 million years ago. It is known as the Age of Reptiles, or the Age of Dinosaurs. Geologists subdivide the Mesozoic Era into three major periods, the Triassic, the Jurassic, and the Cretaceous periods, each between 50 and 80 million years long.
The dinosaurs on our ruler are listed chronologically, that is, in order of their probable first appearance on earth.
This ruler lists people who have made important contributions in any number of scientific disciplines: Medicine, Astronomy, Physics, Chemistry, Mathematics, Biology, Psychology, to name just a few. We have tried to find individuals whose contributions were important to mankind, and who came from various time periods, regions of the world and educational backgrounds.