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Dinosaur Facts

What is a dinosaur?

ApatosaurusThe word "dinosaur" was created in 1842 by Sir Richard Owen, a scientist working at the British Museum, now known at the British Museum of Natural History. His original word was "dinosauria" which means "fearfully great lizard," from the Greek, deinos - "fearfully great" and sauros - "lizard." He created this word after some giant fossils of reptile like creatures were discovered in England earlier in that century. Since that time, "dinosaur" has become a common word all over the world for a group of creatures with strange names and unknown histories.

PalentologistWhat we commonly think of as dinosaurs lived from about 230 million to about 65 million years ago and they ruled the earth for over 140 million years! Check out this "geologic staircase of time" to learn about how old the earth is and when the dinosaurs lived! Some creatures that lived during the time of the dinosaurs still live today such as the alligator and the shark.

Although there has been a lot learned about dinosaurs, scientists are still discovering details to help them determine what dinosaurs looked like, how they lived and what the earth was like during the time they lived. Scientists that study ancient life are called Paleontologists!

Did people live with dinosaurs?

Dino RiderNot even close!!! The dinosaurs were long gone, or extinct, before people appeared in earth's history. 65 million years passed away before man was around. Cartoons and movies make a great story out of cavemen fighting off huge dinosaurs, but it never could really have happened.

Where did the dinosaurs go?

AsteroidThere are several theories as to what happened to the dinosaurs but scientists don't know for sure what really happened. Here are some of the current theories about why the dinosaurs died:

  • An asteroid hit the earth causing climate changes.
  • Massive volcanoes erupting all over the earth caused acid rain and global climate changes.
  • A supernova star caused them to die from radiation.
  • Continental drift altered the climate.
  • They died from disease.

Learn more about dinosaurs and how they may have died! Go to COTF.

Did dinosaurs live in Idaho?

Dinosaurs have not been found in Idaho but there have been a huge number of ancient fossils found in Idaho! The most famous is the Hagerman Horse, one of the earliest known ancestors of the modern day horse! The Hagerman horse was a species known as the Equus simplicidens and lived during the Pliocene period. It may have been related to the zebra.

The Hagerman Horse National Monument is located about 100 miles southeast of Boise and has one of the largest concentrations of horse fossils in North America!! Besides horses, there have been over 140 animal species and 35 plant species identified from the Pliocene age at the Hagerman Horse National Monument!

Hagerman Horse
National Park Service
Hagerman "Horse"
Equus simplicidens

Where did dinosaurs live?

Although dinosaurs have not been found in Idaho there have been dinosaurs found all around us. Dinosaurs have been found in Montana, Utah, Colorado (PDF file), Wyoming and Canada! Dinosaur fossils have been found on all seven continents around the world.

Montana, Utah, Colorado, Wyoming, and Canada

What is a fossil anyway?

fossilA fossil is a kind of mold of a plant or animal that when it died, the remains sank to the bottom of a lake or other body of water. Sediments covered over the plant or animal creating layers and layers that protected the body from fast decay. After much time had passed, these layers of sediment became hard. The layers of sediment eventually turned to rock with the impressions of a plant or animal imbedded in its layers.

Fossils can also be found in amber, volcanic ash, tar pits, bogs, and quicksand. Footprints can also be fossilized.

Kinds of dinosaurs

Dinosaurs can be grouped into two main categories:

Saurischia (lizard-hipped)

Tyrannosaurus RexThe lizard-hipped dinosaur group contains herbivores and carnivores. In this category there are 2 major groups of dinosaurs:

Find out more about Saurischia dinosaurs here.

Ornithischia (bird-hipped)

TriceratopsThe bird-hipped dinosaurs were all herbivores (plant-eaters). In the Ornithischia category there are 3 major groups of dinosaurs:

Learn more about the Ornithischia dinosaurs.

For information on how dinosaurs get named, visit The University of California Museum of Paleontology.

Dinosaur Fossils

The first known dinosaur fossils were found in the 1820's in England and since then dinosaurs have been discovered on all seven continents! So how do paleontologists find their fossils? When scientists go looking for fossils, they investigate areas where the sedimentary rock is between 65 and 230 million years old. But, sometimes paleontologists find dinosaurs by accident. As the earth is exposed to weather, the ground and rock erodes exposing fossils. So as you are exploring - keep your eyes open!

A great fossil site in Idaho is Tolo Lake, which is located near Grangeville. In 1994, construction crews made a surprise discovery when they unearthed a huge bone! This surprise led to the discovery of several mammoths and ancient bison!

Dinosaur bones

Fun Facts


SauropodThe largest dinosaur ever found may have been the Argentinosaurus, first discovered by a farmer in 1988. While no complete Argentinosaurus skeleton has been found, palentologists can estimate the size of the creature from the bones they do have. By their estimations, the Argentinosaurus was 115 feet long and weighed between 80 to 100 tons. Only the modern Blue Whale, at 200 tons, is larger.



The microraptor may have been the smallest dinosaur at 16 inches tall. This dinosaur was discovered in China in the year 2000. It was a bird-like creature with feathers, but may not have been capable of flight. It even had wings on its back legs.


It would be hard to judge the fastest dinosaur since no one was around then to compare them. But the Ornithomimus may have been able to keep up with a present day ostrich which can run up to 43 mph.


The oldest known dinosaurs were from the Triassic period. The prosauropods from Madagascar are the oldest, about 230 million years old.

Largest egg collection

Over 100 dinosaur eggs were discovered in India all in one location thought to be a nest. Large footprints were discovered nearby.


By The Numbers

Dinosaurs by the numbers(Courtesy of Oregon Museum of Science and Industry)

  • 8 inches - The length of a T. Rex tooth - the largest tooth of any meat eater.
  • 500 pounds - The amount of meat a T. Rex could swallow in one bite.
  • 6 feet long - The length of the skull of biggest meat-eater ever, Giganotosaurus.
  • 930 - The number of kinds of dinosaurs.
  • 21 days - The current average time between dinosaur discoveries - the fastest pace ever.
  • 5 feet high, 4 feet wide - The largest bone in the world; the backbone of Argentinosaurus, a plant-eating dinosaur and the largest land animal ever.
  • 24 - The largest known number of dinosaur eggs in a nest.
  • 120 tons - The weight of 1 Argentinosaurus, the heaviest of all land animals, equal to 100 elephants.
  • 33 feet - The longest neck of any animal - Mamenchisaurus, a planteater 68 feet long.
  • 228 million years - The age of the oldest dinosaur, the dog-sized meateater Eoraptor from Argentina.

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