Dinosaurs under the big sky



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Panel: WHAT IS THE DIFFERENCE BETWEEN A HYPOTHESIS AND A THEORY?


When, after exhaustive attempts, no contrary evidence can be found to disprove a hypothesis, it becomes a theory. Scientific theories are scientific hypotheses that have been tested over and over and have not been disproved. The Theory of Gravity—the phenomenon through which all objects attract each other—is a scientific hypothesis that has not yet been disproved and is therefore considered scientific fact. Scientific theories are considered scientific fact if there is ample evidence for their support and no valid contrary evidence has been found to disprove them.

Panel: SCIENCE IS FUN!

Anyone who enjoys making new discoveries will love science! Science is fun because every piece of physical evidence is the result of a new discovery. Paleontology is a science where new discoveries can include discovering fossilized remains of animals no human has ever seen. At the Museum of the Rockies, we have found or named more than a dozen new species of dinosaurs. Einiosaurus procurvicornis and Achelousaurus horneri are two of these new species. You can see the Achelousaurus skull in the Hallway of Growth and Behavior.


Panel: WHAT IS PALEONTOLOGY?


Paleontology is the study of extinct life. Vertebrate paleontology is the study of extinct vertebrate animals (animals with backbones). Some vertebrate paleontologists study dinosaurs. Dr. Jack Horner, the retired curator of this exhibit, is a vertebrate paleontologist who studies dinosaurs.

Panel: THE THREE MOST IMPORTANT SCIENTIFIC THEORIES IN PALEONTOLOGY


  1. THEORY OF EXTINCTION: Species once lived that are now extinct.

  2. THEORY OF DARWINIAN EVOLUTION: New species arise through a process of descent with modification via natural selection.

  3. THEORY OF RADIOMETRIC DATING: Elemental isotopes have predictable rates of decay, and these rates can be used to determine the age of rocks.

These three theories are considered scientific facts because no one has found physical evidence to disprove them.



Panel: WHAT IS A DINOSAUR?


Dinosaurs were a group of reptiles that lived 230-65 million years ago. They are the only group of reptiles that walked with their legs directly underneath their bodies. They did not sprawl like other reptiles. Some dinosaurs were bipedal (walked on two legs), while others were quadrupedal (walked on four legs). There are two major groups of dinosaurs: non-avian (extinct) and avian (birds). All non-avian dinosaurs have been extinct for at least 65 million years. This includes animals like Tyrannosaurus, Stegosaurus, Diplodocus, Triceratops, Maiasaura, Centrosaurus, and Velociraptor, among many others.


Panel: ARE ALL EXTINCT ANIMALS DINOSAURS?


NO! The woolly mammoth, Dimetrodon, saber-toothed tiger, swimming reptiles, and flying reptiles were not dinosaurs, even though they are all extinct.



Panel: ARE THERE ANY DINOSAURS ALIVE TODAY?


Yes! Birds are a group of living dinosaurs. Paleontologists call the extinct dinosaurs non-avian dinosaurs. Living dinosaurs are called avian dinosaurs, or birds. Evidence for this hypothesis is presented throughout this exhibit. In this exhibit the non-avian dinosaurs are called dinosaurs, and the avian dinosaurs are called birds.



Panel: DID HUMANS AND DINOSAURS EVER LIVE TOGETHER?


Humans and avian dinosaurs (birds) do live together, but humans did not live with non-avian dinosaurs. Non-avian dinosaurs went extinct 65 million years ago, 64 million years before the first true humans existed on Earth. Birds did live at the same time as non-avian dinosaurs.


Panel: WHERE DID DINOSAURS LIVE AND DIE?


Dinosaurs lived and died on every continent, including Antarctica, for more than 150 million years. During this time, the earth was much warmer than it is today, and much more of its surface could be inhabited by dinosaurs and other animals.


Panel: WHERE CAN DINOSAUR FOSSILS BE FOUND?

Dinosaur remains can only be found in places where the right age rock is exposed at the surface of the ground. The right age rock is 230 million to 65 million years old—the time non-avian dinosaurs roamed the earth. Some parts of Montana are ideal for hunting dinosaur fossils, but in places like Florida and Ohio, the right age rocks have long since eroded away. Dinosaur skeletons can never be found in these states. In many other places the right age rock is hundreds or thousands of feet underground, and too deep to excavate.


Panel: FOSSILS AND FOSSILIZATION


Fossils are the mineralized or otherwise preserved remains or traces of once-living animals, plants, and other organisms. Fossils provide a great deal of information about past life on Earth. Fossilization occurs when organic material is replaced by mineral substances. Permineralization and replacement are two different kinds of fossilization. In permineralization the pores (and other open spaces) are filled with mineral material, but the original organic hard material remains in place. In replacement the original organic hard material is completely replaced by minerals. Note: Scientists use fossils as primary physical evidence to reconstruct ancient climates and environments, to determine the ages of rocks worldwide, to determine the lifestyles of extinct animals, and to understand the process of evolution. Remains such as bones, teeth, horns, shells, imprints, and tracks can be fossilized.

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