Fossil specimens of pachycephalosuarians Are often only a piece of the skull cap, without other skeletal bones nearby. Explain why this is the case. What happens to the rest of the skeleton begore or diring fossilization?
Answers
Paleoanthropology is the study of early forms of humans and their primate ancestors. It is similar to paleontology except its focus is documenting and understanding human biological and cultural evolution. Paleoanthropologists do not look for dinosaurs and other early creatures. However, like paleontology, the data for paleoanthropology is found mainly in the fossil record. Before examining this evidence, it is necessary to first learn what fossils are and how they are formed. In addition, it is important to know how paleoanthropologists date fossils and other evidence of the prehistoric past. In order to understand fossils, it is useful to learn how they formed. Taphonomy is the study of the conditions under which plants, animals, and other organisms become altered after death and sometimes preserved as fossils. Research into these matters has shown that fossilization is a rare phenomenon. In order for a fossil to form, the body must not be eaten or destroyed by erosion and other natural forces. Preservation would most likely occur if the organism were buried quickly and deeply. In most environments, soft body parts, such as skin, muscle, fat, and internal organs, deteriorate rapidly and leave no trace. Only very rarely do we find the casts of such tissues. Similarly, the totally soft-bodied creatures, like jellyfish, are very uncommon fossils. Hard body parts, such as dense bones, teeth, and shells, are what most often are preserved. It is likely that the vast majority of fossils will never be found before they are destroyed by erosion. That coupled with the fact that extremely few living things are preserved long enough after death to become fossils makes the large collections of fossils in the museums of the world quite remarkable. It is a testament to the tenacious searching by fossil hunters over the last two centuries. People often think of fossils as being mineralized bones or shells stored in museums. However, they can be any remains or traces of ancient organisms. They even can be footprints, burrows, or casts of bodies with nothing else surviving. Some of the best preserved fossils were rapidly frozen in permafrost soil or ice, dehydrated in dry desert caves, or encased in tree resin that hardened into amber. In any of these three environmental conditions, even soft body parts can be remarkably well preserved indefinitely. Several wooly mammoths that lived during the last ice age have been excavated from frozen tundra soil in Siberia. Some were still in such good condition, that parts of their bodies were fed to the dogs of the Russian scientists who found them. One small mammoth was even transported intact to Moscow where it is kept in a specially made large freezer that allows it to be displayed for the general public. The oldest frozen human remains were discovered on the edge of a glacier in the Alps of northern Italy in 1991. It was a well preserved body of a man, along with his clothes and tools, who died about 5,300 years ago. Even tattoos on his skin were preserved by the extreme cold. Well preserved body from a Danish bog("Tollund Man", 4th century B.C.)Spider preserved in amber.The mummies of ancient Egypt were preserved by extreme, continuous dehydration. The complicated mummification practices used to prepare the bodies of important people only accelerated the dehydration, but it was not necessary in the dry conditions of Egypt. Mummies from other cultures have been found in deserts around the globe. Some of the best preserved ones were discovered in the Tarim Basin of Western China.Bodies of people submerged in stagnant swamps or bogs in Denmark and the British Isles thousands of years ago have also been found in remarkably good condition with their soft tissues intact. They were preserved naturally by cold anaerobic environments and by tannins with antibiotic properties released from decaying plants in the swamps. The bodies were essentially tanned like shoe leather. These conditions are hostile for bacteria and other organisms that normally reduce organic matter to basic soil nutrients in a matter of months.
Amber is a fossilized resin that originally oozed from cone bearing trees, such as pines and firs, millions of years ago. When fresh, it primarily consisted of sticky, non-water-soluble organic resins and volatile essential oils. Occasionally the resin fell on small creatures and trapped them. Under the pressure of burial deep underground for long periods of time, the resin was converted into a rock-like substance that is most commonly yellow-orange and translucent. Often well preserved plant fragments and animals can be seen within amber nodules. The oldest animal life found in amber so far are single cell organisms that date back to 220 million years ago.