Fossils - Introduction

Introduction

From dinosaurs to prehistoric humans, fossils provide a glimpse into Earth's past events, environment, and life forms. FossilsThe remains, trace, or impressions of a living organism that inhabited Earth more than ten thousand years ago. are the remains or traces of ancient organisms. Fossils can range in age from a mere ten thousand years to several billion years old. They can be microscopic or hundreds of feet long. From the Latin word fossilis, meaning something dug up, fossils are found on every continent. Scientists who study fossils are called paleontologistsScientist who studies the life of past geological periods as known from fossil remains..

Studying fossils has revealed a wealth of data about Earth's 4.6 billion-year-old history, including its past geography, weather, animals, plants, biodiversity, and how life has changed over time. Fossils can provide information on past environmental conditions. Different types of plants, for example, require specific temperature, acidity, and amounts of water to live. By studying fossils, scientists can also determine an ancient animal's age, health, eating habits, and movements. Unearthing 3.5 billion-year-old bacteria fossils led to theories on when life began and how it impacted the development of future life. Other fossil evidence shows how continents have shifted over time. Fossils can also create an understanding of modern Earth and how people can best preserve the planet.

Words to Know

Control experiment
A setup that is identical to the experiment, but is not affected by the variable that acts on the experimental group.

Until about two centuries ago, fossils were mysterious objects that cultures explained in varying ways. Some theorized that fossils were weapons left behind from the gods; others believed they were the seeds of adult animals, or the remains of animals that did not make it onto Noah's ark. In the 1800s, scientists began turning up fossils of strange animals by the thousands: the giant reptilian ichthyosaur, the 40-foot-long Megalosaurus, and teeth from the immense plant-eating Iguanodon. People began to understand what fossils were and, in the late 1800s, fossil hunting began in earnest.

Did You Know?

  • The fossil record shows a lot of extinct species: Scientists theorize that of all the species that ever lived on Earth, over 90 percent of them are now extinct.
  • Most of the dinosaur skeletons shown in museums are lightweight replicas of the original fossils to prevent damage and to keep the originals available for study.
  • History is filled with important fossils discovered by amateurs. In 1990, amateur fossil hunter Sue Hendrickson discovered the largest, most complete, and best-preserved Tyrannosaurus rex—it was 67 million years old and had a 5-foot-long (1.5-meter-long) skull.
  • In 2002 the oldest known skull related to humans was uncovered in Africa, a six-to-seven-million-year-old relic of our past.
  • In 2001 researchers found the largest, most complete fossil of a cockroach—it was about the size of a mouse and lived 55 million years before the first dinosaurs.
  • Along with fossil dung, scientists also study fossil vomit. In 2002 scientists discovered what they estimate is the world's oldest fossilized vomit, believed to be from a 160-million-year-old marine reptile!