Rulers of the Mesozoic

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.

Dinosaurs, a diverse group of reptiles, first appeared in the early to middle Triassic, but these creatures were much smaller than the enormous and better-know “dinos” that were to come later. The Jurassic was a golden age for the herbivorous dinosaurs such as Brachiosaurus and Apatosaurus, among the largest creatures to have walked the earth.

You often see images of a Stegosaurus battling a Triceratops. That would never have happened, because the Triceratops lived much later, during the Cretaceous. The two genera (that’s the plural of genus) missed each other by about 80 million years.

The dinosaurs on our ruler are listed chronologically, that is, in order of their probable first appearance on earth.

There are three “head” images on the ruler, one for each of the periods. The Triassic is represented by Asilisaurus, the Jurassic by Brachiosaurus, and the Cretaceous by Tyrannosaurus Rex, which translates to “Tyrant Lizard King”.

If you like this ruler, you might also be interested in the State Birds Ruler.