Paper Topic:

Evolution

Fossils : A Direct Link to Macroevolution

Paleontology is used to study macroevolution , or large evolutionary trends . Fossils give us the only true evidence of the history of evolution . Fossils are bones , shells , or teeth that have been buried in rock but can also be outlines of leaves , footprints , or trails , called trace fossils . Fossils are formed when residue covers some type of material , such as bone . By piecemeal , the bone absorbs chemicals from rocks surrounding it . In the end , all that is left is basically a rock in the shape of the

original material

Fossil records and new radioactive carbon dating both help us determine the age of the fossils and the environment from which a plant or animal lived . Also , we can learn about the balance of gases in the atmosphere from which the fossil originated

Fossil records provide numerous examples of macroevolution over huge geologic time spans . We know that certain animals roamed the Earth during different time periods and some , though most are not , are still alive today . Trilobites , crinoids and brachiopods ruled over shallow water environments in the Paleozoic era 540 million years ago to 250 million years ago . Rocks from that era are peppered with fossils of these extinct or less creatures

There are no trilobites alive today but during the Paleozoic era , these varied arthropods scampered about feasting on food particles from the ocean floor . With more than 15 ,000 species identified , they are the most variant group in the fossil record

Crinoids are less plentiful today with only a few hundred species remaining . But during the Paleozoic era , these creatures , known as sea lilies , were very common . So much so that parts of their skeletons make up entire rocks in certain areas of the central United States , which used to be part of the shallow ocean floor . To flee from predators today 's crinoids find homage in the deep ocean or tucked into cracks in rocks

Brachiopods are still alive but less common today . With shells like clams for housing , they have little nets made for skimming seawater for food . During the Paleozoic era there were very diverse with sixteen plus s and thousands of species

The preservation of the fossils of these Paleozoic creatures enables scientists to visualize what the shallow waters of the oceans were like millions of years ago . The ecosystems and fossils are somewhat of a diary or journal of biological evolution in the shallow ocean waters and other environments as well . Paleontologists study the fossils in sedimentary rocks from various geologic time periods and locations across the globe...

2 pages

21.0 KB

Free sing-up