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PaleontologyTable of Contents
Teaching Tip: Fossils When animals or plants are rapidly buried in layers of mud during a natural catastrophe, their bodies are protected from normal processes of decay: scavengers, bacteria, and chemicals are prevented from breaking down their bodies at the usual rate. The hard parts of the animals (such as their bones, teeth, and shells) are eventually replaced with minerals from the mud, which turn them into rock. The soft parts of the specimen, such as the scales of a fish or the leaves of a plant, sometimes leave a colored imprint in rock before they eventually decay. Trees or other organic matter that are covered with silica-rich water become petrified--they turn into solid mineral. All of these methods result in what we know as fossils. Fossils are most commonly found in limestone, shale, and sandstone, all relatively soft rock that erodes more easily than most rocks do. As the rock gradually wears away, the fossil layers within it are exposed. One enjoyable way of demonstrating how fossils are made is to make fossil casts. Start with a clean tuna can or styrofoam bowl and fill it to a depth of about 1" with modeling clay. Then press a plastic animal, rock, or other object halfway into the clay. Remove the object, leaving a clean imprint in the clay. A paleontologist is a scientist who studies fossils to find out more about extinct species or about any species that are evident in the fossil record. Teaching Tip: Do We Know What Dinosaurs Looked Like? What did dinosaurs look like? If you hear the word "Stegosaurus", what picture immediately comes to mind? What about "Tyrannosaurus"? "Brontosaurus"? You've probably seen illustrations or models of many different dinosaurs: gigantic creatures with long necks and tails, stocky creatures with hard heads and horns or fierce teeth, and even swimming dinosaur-like creatures! But have you ever wondered what scientists really know about an extinct species? What they looked like? What they ate? How do scientists find out that sort of information? Complete dinosaur skeletons are rare; usually a paleontologist has to piece together a fragmented skeleton and use the available parts to try to determine the way the full skeleton would look. Sometimes, fossilized skeletons get put together wrong--the case of the Brontosaurus is an example of this. The Brontosaurus, perhaps the most famous dinosaur after the T. rex, is really an Apatosaurus, with the head of a Camarasaurus. However, the name Brontosaurus is still the most popular. Dinosaurs are a tricky thing to study, since the evidence about them is limited. It's easy to confuse where science ends and assumption begins--forming theories is part of a paleontologist's job, but theories should not be accepted as fact when based on insufficient evidence. Good science is careful to go no further than the evidence, clearly distinguishing between theory and facts. The pictures we see of dinosaurs are models based on the best idea scientists have of them. Scientists base their assumptions about dinosaurs on fossilized bones, claws, teeth, bony plates, eggs, dung, and footprints. They also consider characteristics of similar animals, such as living reptiles. Even this evidence can be tricky to decipher, though: for instance, giant pandas and some other mammals have sharp teeth, yet are herbivores, so sharp teeth on a dinosaur does not necessarily preclude the possibility of it eating primarily plants. You can demonstrate to your kids how easy it is to make wrong guesses about what an animal looks like based on its bones. Using this picture of a skeleton, have your children draw what they think the bones would look like assembled. Then draw what they think the live animal looks like. Count the vertebrae, toes, etc.; can they tell how many of each body part the animal has? What do they know for sure about the animal? Don't tell them until after they're done that the skeleton actually belongs to a mouse. How close were their guesses to the truth? In the same way, good scientists do their best to imagine accurately from the evidence, but cannot always be certain they are headed in the right direction. In the case of things which cannot be experienced again or seen firsthand (e.g., the Flood), science is limited in what it can prove. Thus, both a creationist viewpoint and an evolutionist viewpoint are more dogmatic than scientific. Teaching Tip: "Here be Dragons" One aspect of dinosaurs that is important to consider and discuss is how "dinosaur theory" differs between those who believe in evolution and those who believe in biblical creationism. Both sides are offering answers, but they can't both be right! When were dinosaurs alive? Did people live at the same time as they did? Evolutionists claim that dinosaurs lived 65-245 million years ago during the Mesozoic Age, and were extinct long before man evolved. Creationists, on the other hand, believe that man and dinosaur lived at the same time. And rather than dinosaurs ruling the earth, mankind was given the task of ruling it. How did dinosaurs become extinct? One theory that evolutionists put forth is that an asteroid wiped all the dinosaurs out: they could not survive in the changed conditions of the earth that were caused by the asteroid's crash. The theory that is most likely from a creationist viewpoint, however, is that the majority of dinosaurs died in the Great Flood. This supports the evidence of so many dinosaur fossils being together in some places; there must have been many dinosaurs before the Flood, that were buried in silt from the flood waters. However, not all dinosaurs were killed: God brought at least a pair of every animal to Noah, to be preserved on the Ark. So what happened to those dinosaurs after the Flood? Most of them probably died out slowly, based on the availability of food. Dinosaurs, of course, were not the only animals to become extinct--there are over a thousand plant and animal species that have died out in the last few centuries alone. Are there still dinosaurs? According to the evolutionist viewpoint, dinosaurs became extinct more than 60 million years ago. From a biblical creationist viewpoint, however, there is no reason to believe that all dinosaurs died out after the Flood. In Job 40:15-24 and 41:1-34, God talks about mighty creatures that could be dinosaurs. (As near as scholars can discover, Job lived in 2000 BC or slightly after.) Beside the Bible, there are universal stories of dinosaur-like creatures. Just like worldwide stories of a great flood, there are dragon tales from places all around the earth. Perhaps the most famous dragons are from China, Babylon (the story of Gilgamesh), and the one that Saint George is supposed to have killed. It seems likely that these legends were caused by some real creature and, as with all myths, the truth was expanded upon to make the story more exciting. There's even evidence that supports the possibility of a fire-breathing lizard, though that might sound hard to believe! The bombardier beetle, which can be found in North America, has chemicals in its abdomen that it is able to shoot out of a "cannon" in its rear. When the chemicals mix, they cause a spurt of smelly, boiling liquid. It is possible that there was a dinosaur with similar capabilities. The coelacanth (say it "see-luh-kanth") is a fish that is present in many fossil records, and was long believed to be extinct. However, in the 1950s a live coelacanth was found off the east coast of Africa. Animals like this, which were once believed to be extinct, are called "living fossils" by evolutionists. Whether there are any actual dinosaurs alive today is speculation; no one has yet found conclusive proof. Although we have learned much about dinosaurs, they are still a mystery! Teaching Tip: Frozen Mammoths, Mummified People Fossilization isn't the only way for a creature to be preserved. Natural preservatives such as ice, sand, and peat bogs have kept the bodies of both animals and people from decaying, making them records of ancient times in a similar way as fossils. Extinct mammoths and mastodons belong to the same order as the two living elephant species: Proboscidea. Mammoth bodies have been found in Siberia and other places, frozen and so well preserved that in at least one instance their meat was given to sled dogs to eat! The ice that the mammoths were "buried" in worked like a giant freezer, effectively keeping the bodies from decaying. Mammoths most likely were not able to survive entirely in a land of snow and ice, based on the evidence of living elephants, who have to eat a huge amount of plants every day in order to stay alive. Mammoths were about the size of an Indian elephant at the largest, and some were smaller. (Male Indian elephants are about 9' at shoulder height and weigh five tons; females are smaller.) People can also be preserved, as mummies. In Egypt, the first mummies were accidental--bodies buried in hot, dry sand naturally mummified. Later, embalmers removed a person's organs immediately after death, so that the body would not begin to decay. They washed the body and then dried it out with a salt called natron. (Natron is a mixture of sodium bicarbonate--baking soda--and sodium carbonate.) After the body was dry, it was anointed with scented oils and then covered with resin for further preservation. For the final touch, the body was wrapped in cloths, placed in a sarcophagus, and then sealed in a tomb. Not all mummies were preserved on purpose the way ancient Egyptians were, though. The "Bog People", found in locations throughout Europe, are well-preserved bodies that did not decay, due to properties of the peat bogs they were found in. The sphagnum moss in the bogs works as an antibacterial, and the bog itself is an anaerobic environment which helps prevent decay and "tans" the bodies of the Bog People like leather. Some of the bodies are thousands of years old, and many still had clothes and other personal effects with their bodies when they were found. You can demonstrate how mummification works, using some fruit or other food and a bag of salt. First, show your children how grapes and plums look compared to raisins and prunes. The dehydration process in Egyptian mummification caused somewhat similar results! Pick out the kind of fruit that you want to "mummify" and put in a container, then cover it with salt. You'll need to let the fruit sit for two or more weeks before it's dried all the way. If you'd like to compare mummification to the freeze method, put one of the same kind of fruit in the freezer for several days and then compare it to the salt-dried fruit. How are they different? Which seems most helpful for scientific study? Noteworthy Scientist: Georges Cuvier (1769-1832) Georges Cuvier, the great comparative anatomist, was born in August 1769 in the Jura Mountains between France and Switzerland. As a young man, he studied in the German town of Stuttgart and then worked as tutor for a noble family in Normandy. In 1795 Cuvier moved to Paris, where he taught and did research at the Musée National d'Histoire Naturelle (National Museum of Natural History). During his lifetime he served in government positions under three widely different French regimes: the Revolution directorate, Napoleon, and the monarchy. Cuvier, who was skilled at accurately reconstructing skeletons, founded the science of vertebrate paleontology and established that extinction of species was a fact. He did careful comparisons of elephant anatomy and demonstrated that Indian and African elephants were separate species from each other, and that the species that mammoth fossils from Siberia and Europe belonged to were distinct species that differed from living elephants. At the same time, Cuvier believed that evolution from one species to another was impossible--species were too unique. An organism could not survive a change to its anatomy. He examined mummified cats and ibises that Napoleon brought back from Egypt, and showed that they were the same as living species. To explain the extinction of species, Cuvier speculated that there must be periodic "revolutions" in the earth's history; times of natural catastrophe that affected geology. Cuvier classified animals in four branches: Vertebrata (animals having backbones), Articulata (arthropods and segmented worms), Radiata (echinoderms and cnidarians), and Mollusca (all other soft invertebrates). He believed similarities between animals were based on shared functions, not ancestors, as later evolutionary scientists suggested. Like Pasteur and Fabre, Georges Cuvier was a French scientist who was influential during his lifetime. He was acclaimed by both the scientific community and the government: Louis Agassiz, another famous scientist, was one of his followers; and under the rule of the monarchy he was made a baron. Fabulous Facts It just keeps growing and growing €¦ Dinosaurs, like other reptiles, probably did not stop growing during their lifetime. After reaching maturity, they only grew more slowly. If you consider the longer lifespan of mankind in the beginning as representative of all lifespans at the time, this might explain why some dinosaurs were so enormous. Fossil Fuels! The term "fossil fuel" is used to refer to fuels formed from plant remains: coal comes from plants who have nothing left but carbon, and oil is thought to be carbonized algae. The Scientific Speaker Dinosaur comes from the Greek deinos ("monstrous" or "terrible") and sauros ("lizard"). The name was first used by the British scientist Richard Owen in the 1840s; he classed the three then-known species as Dinosauria. Gastroliths are gizzard stones, located in the stomachs of dinosaurs to aid their digestion. The stones helped grind up food that the dinosaurs ate. Some living birds, reptiles, and fish also have gastroliths. Fossil fittingly comes from the Latin for "dug up". Science Links This page lists many stories of dinosaur-like creatures throughout history, including one by the first English printer, William Caxton. http://www.ldolphin.org/cooper/ch10.html Here's an e-text of Beowulf, the first known work of English literature. After defeating the monster Grendel, Beowulf fights a dragon. http://etext.library.adelaide.edu.au/b/b48g/ In 1938, the first hint that coelacanths weren't extinct came when a South African natural history museum curator got hold of an odd-looking fish. Read the story of the original discovery at this site: http://www.pbs.org/wgbh/nova/fish/letters.html. |
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