The Geology-Paleontology Connection
Geologists use a special technique called radiometric dating to figure out the age of different rocks. Once paleontologists know the age of a rock, they know the age of the fossils that are inside it. This helps create a timeline of when different dinosaurs lived. Because Pisanosaurus remains were found in much older rocks than T. rex remains, we know that Pisanosaurus lived before T. rex. Geologists have divided Earth's history into four major
eras. The Mesozoic (Meh-zuh-ZOH-ik) Era lasted from 248 million years ago to 65 million years ago. Today, we live in the Cenozoic (sen-oh-ZOH-ik) Era.

James Hutton, the First Rock Star
Before the mid-1700s, most scientists believed that rocks formed as a result of a great flood. James Hutton, a Scottish scientist who lived from 1726-1797 didn't agree. Instead, Hutton proposed the theory that rocks are slowly worn down by water and wind over thousands of years. Then, this eroded material is washed into the oceans where it builds into layers of sedimentary rock. Hutton's theories caused much controversy during his time. However, today Hutton's "radical" ideas are so widely accepted that he is known as the "Father of Modern Geology."