How was the microscope important in determining the true nature of fossils

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Fossils are physical evidence of preexisting organisms, either plant or animal. The most common and obvious fossils are the preserved skeletal remains of animals. Other fossils, which are also evidence of past organisms, include leaf impressions, tracks and trails, burrows, droppings, and root casts. Microfossils are the microscopic skeletons of previously existing plants or animals, and their examination requires an optical or an electron microscope for close study. A very small fraction of the organisms that have lived on the Earth is found in the fossil record: Many did not possess skeletons or other hard parts that could be preserved; many did not survive the process of fossilization, wherein skeletons and tissues are replaced by minerals; and many were subsequently destroyed either by chemical or physical processes such as recrystallization, metamorphism, or erosion.

Fossils of any kind are useful in "reading the rock record," meaning they help us decipher the history of the earth. They can help us determine the geologic age and environment (the paleoenvironment) in which they were deposited. Finally, and if the fossil record is complete enough, their study can help us better understand the evolution (or progression) of life through geologic time.

Our understanding of the meaning of fossils is based on the accumulated knowledge from previous generations of investigators who carefully recorded the identity and distribution of fossils from numerous geologic exposures or samples from wells and recorded their findings in the scientific literature. When the regional or global distribution of fossils through geologic time is taken into consideration, we can gain important insights into such phenomena as continental drift, community migration, and climatic (paleoclimatic) reconstruction.

Fossils are the preserved remains, or traces of remains, of ancient organisms. Fossils are not the remains of the organism itself! They are rocks. A fossil can preserve an entire organism or just part of one. Bones, shells, feathers, and leaves can all become fossils. Fossils can be very large or very small. Microfossils are only visible with a microscope. Bacteria and pollen are microfossils. Macrofossils can be several meters long and weigh several tons. Macrofossils can be petrified trees or dinosaur bones. Preserved remains become fossils if they reach an age of about 10,000 years. Fossils can come from the Archaeaean Eon (which began almost 4 billion years ago) all the way up to the Holocene Epoch (which continues today). The fossilized teeth of wooly mammoths are some of our most "recent" fossils. Some of the oldest fossils are those of ancient algae that lived in the ocean more than 3 billion years ago. Fossilization The word fossil comes from the Latin word fossus, meaning "having been dug up." Fossils are often found in rock formations deep in the earth. Fossilization is the process of remains becoming fossils. Fossilization is rare. Most organisms decompose fairly quickly after they die. For an organism to be fossilized, the remains usually need to be covered by sediment soon after death. Sediment can include the sandy seafloor, lava, and even sticky tar. Over time, minerals in the sediment seep into the remains. The remains become fossilized. Fossilization usually occur in organisms with hard, bony body parts, such as skeletons, teeth, or shells. Soft-bodied organisms, such as worms, are rarely fossilized. Sometimes, however, the sticky resin of a tree can become fossilized. This is called fossilized resin or amber. Amber can preserve the bodies of many delicate, soft-bodied organisms, such as ants, flies, and mosquitoes. Body Fossils and Trace Fossils The fossils of bones, teeth, and shells are called body fossils. Most dinosaur fossils are collections of body fossils. Trace fossils are rocks that have preserved evidence of biological activity. They are not fossilized remains, just the traces of organisms. The imprint of an ancient leaf or footprint is a trace fossil. Burrows can also create impressions in soft rocks or mud, leaving a trace fossil. Paleontologists Paleontologists are people who study fossils. Paleontologists find and study fossils all over the world, in almost every environment, from the hot desert to the humid jungle. Studying fossils helps them learn about when and how different species lived millions of years ago. Sometimes, fossils tell scientists how the Earth has changed. Fossils of ancient marine animals called ammonites have been unearthed in the highest mountain range in the world, the Himalayas in Nepal. This tells scientists that millions of years ago, the rocks that became the Himalayas were at the bottom of the ocean. Fossils of an ancient giant shark, a megalodon, have been found in the landlocked U.S. state of Utah. This tells scientists that millions of years ago, the middle of North America was probably entirely underwater.

Fast Fact

Mary Anning
The 19th-century British fossil collector Mary Anning proved you don't have to be a paleontologist to contribute to science. Anning was one of the first people to collect, display, and correctly identify the fossils of ichthyosaurs, plesiosaurs, and pterosaurs. Her contributions to the understanding of Jurassic life were so impressive that in 2010, Anning was named among the ten British women who have most influenced the history of science.

Fast Fact

Microfossils
Even though most of us have only seen dinosaur fossils in museums, most fossils are not that big. Some of them are so small, you can't see them without a microscope.

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