Which condition aids the process of fossilization

Inheritance 5. Genetic Modification 4: Ecology 1. Energy Flow 3. Carbon Cycling 4. Climate Change 5: Evolution 1. Evolution Evidence 2. Natural Selection 3. Classification 4. Cladistics 6: Human Physiology 1. Digestion 2. The Blood System 3. Disease Defences 4.

Gas Exchange 5. Homeostasis Higher Level 7: Nucleic Acids 1. Although in many cases the vestigial structure is of no direct harm, all structures require extra energy in terms of development, maintenance, and weight and are also a risk in terms of disease e. The vestigial versions of a structure can be compared to the original version of the structure in other species in order to determine the homology of the structure.

Homologous structures indicate common ancestry with those organisms that have a functional version of the structure. Vestigial traits can still be considered adaptations because an adaptation is often defined as a trait that has been favored by natural selection.

Adaptations, therefore, need not be adaptive, as long as they were at some point. The biological distribution of species is based on the movement of tectonic plates over a period of time. Biogeography is the study of the geographic distribution of living things and the abiotic factors that affect their distribution. Abiotic factors, such as temperature and rainfall, vary based on latitude and elevation, primarily.

As these abiotic factors change, the composition of plant and animal communities also changes. Ecologists who study biogeography examine patterns of species distribution. No species exists everywhere; for example, the Venus flytrap is endemic to a small area in North and South Carolina. An endemic species is one which is naturally found only in a specific geographic area that is usually restricted in size. Other species are generalists: species which live in a wide variety of geographic areas; the raccoon, for example, is native to most of North and Central America.

Since species distribution patterns are based on biotic and abiotic factors and their influences during the very long periods of time required for species evolution, early studies of biogeography were closely linked to the emergence of evolutionary thinking in the eighteenth century.

Some of the most distinctive assemblages of plants and animals occur in regions that have been physically separated for millions of years by geographic barriers. Biologists estimate that Australia, for example, has between , and , species of plants and animals. Australia : Australia is home to many endemic species.

The a wallaby Wallabia bicolor , a medium-sized member of the kangaroo family, is a pouched mammal, or marsupial. The b echidna Tachyglossus aculeatus is an egg-laying mammal.

The geographic distribution of organisms on the planet follows patterns that are best explained by evolution in conjunction with the movement of tectonic plates over geological time. Broad groups that evolved before the breakup of the supercontinent Pangaea about million years ago are distributed worldwide.

Groups that evolved since the breakup appear uniquely in regions of the planet, such as the unique flora and fauna of northern continents that formed from the supercontinent Laurasia and of the southern continents that formed from the supercontinent Gondwana.

Biogeography : The Proteacea family of plants evolved before the supercontinent Gondwana broke up. Today, members of this plant family are found throughout the southern hemisphere shown in red.

Privacy Policy. Skip to main content. Evolution and the Origin of Species. Search for:. Evidence of Evolution. The Fossil Record as Evidence for Evolution Fossils tell us when organisms lived, as well as provide evidence for the progression and evolution of life on earth over millions of years.

Learning Objectives Synthesize the contributions of the fossil record to our understanding of evolution. Key Takeaways Key Points Fossils are the preserved remains or traces of animals, plants, and other organisms from the past.

Fossils are important evidence for evolution because they show that life on earth was once different from life found on earth today. Usually only a portion of an organism is preserved as a fossil, such as body fossils bones and exoskeletons , trace fossils feces and footprints , and chemofossils biochemical signals. Paleontologists can determine the age of fossils using methods like radiometric dating and categorize them to determine the evolutionary relationships between organisms.

Key Terms biomarker : A substance used as an indicator of a biological state, most commonly disease. Fossil Formation Fossils can form under ideal conditions by preservation, permineralization, molding casting , replacement, or compression. Learning Objectives Predict the conditions suitable to fossil formation. Key Takeaways Key Points Preservation of remains in amber or other substances is the rarest from of fossilization; this mechanism allows scientists to study the skin, hair, and organs of ancient creatures.

Permineralization, where minerals like silica fill the empty spaces of shells, is the most common form of fossilization. Molds form when shells or bones dissolve, leaving behind an empty depression; a cast is then formed when the depression is filled by sediment. Replacement occurs when the original shell or bone dissolves away and is replaced by a different mineral; when this occurs with permineralization, it is called petrification. In compression, the most common form of fossilization of leaves and ferns, a dark imprint of the fossil remains.

Decay, chemical weathering, erosion, and predators are factors that deter fossilization. Fossilization of soft body parts is rare, and hard parts are better preserved when buried. Key Terms amber : a hard, generally yellow to brown translucent fossil resin permineralization : form of fossilization in which minerals are deposited in the pores of bone and similar hard animal parts petrification : process by which organic material is converted into stone through the replacement of the original material and the filling of the original pore spaces with minerals.

Gaps in the Fossil Record Because not all animals have bodies which fossilize easily, the fossil record is considered incomplete. Learning Objectives Explain the gap in the fossil record. Because hard body parts are more easily preserved than soft body parts, there are more fossils of animals with hard body parts, such as vertebrates, echinoderms, brachiopods, and some groups of arthropods.

Key Terms transitional fossil : Fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group. Carbon Dating and Estimating Fossil Age The age of fossils can be determined using stratigraphy, biostratigraphy, and radiocarbon dating. Learning Objectives Summarize the available methods for dating fossils. Key Takeaways Key Points Determining the ages of fossils is an important step in mapping out how life evolved across geologic time.

The study of stratigraphy enables scientists to determine the age of a fossil if they know the age of layers of rock that surround it. Biostratigraphy enables scientists to match rocks with particular fossils to other rocks with those fossils to determine age. Scientists use carbon dating when determining the age of fossils that are less than 60, years old, and that are composed of organic materials such as wood or leather.

Key Terms half-life : The time required for half of the nuclei in a sample of a specific isotope to undergo radioactive decay. The Fossil Record and the Evolution of the Modern Horse The detailed fossil record of horses has provided insight into their evolutionary progress. Learning Objectives Analyze the fossil record to understand the evolution of horses. Key Takeaways Key Points A dog-like organism gave rise to the first horse ancestors million years ago.

The fossil record shows modern horses moved from tropical forests to prairie habitats, developed teeth, and grew in size. The first equid fossil was a tooth from the extinct species Equus curvidens found in Paris in the s. Thomas Huxley popularized the evolutionary sequence of horses, which became one of the most common examples of clear evolutionary progression. Horse evolution was previously believed to be a linear progress, but after more fossils were discovered, it was determined the evolution of horses was more complex and multi-branched.

Horses have evolved from gradual change anagenesis as well as abrupt progression and division cladogenesis. Key Terms cladogenesis : An evolutionary splitting event in which each branch and its smaller branches forms a clade. Homologous Structures Homologous structures are similar structures that evolved from a common ancestor. Learning Objectives Describe the connection between evolution and the appearance of homologous structures.

Key Takeaways Key Points Homology is a relationship defined between structures or DNA derived from a common ancestor and illustrates descent from a common ancestor. Analogous structures are physically but not genetically similar structures that were not present the last common ancestor.

Homology can also be partial; new structures can evolve through the combination or parts of developmental pathways. Analogy may also be referred to as homoplasy, which is further divided into parallelism, reversal, and convergence. Key Terms homology : A correspondence of structures in two life forms with a common evolutionary origin, such as flippers and hands. The most important thing to do if you find what you believe is a fossil or an artifact is to leave it where you found it.

When scientists study these items, we need to know exactly where they came from so that we can learn everything possible about them. Perfect for amateur paleontologists, students, and professional scientists alike, The Digital Atlas of Ancient Life is a free app created by scientists at the University of Kansas to help people identify fossils in the field. A rock or concretion, like the one I showed to my professor, will be solid, and the inside of the rock will look like the outside.

Fossil bone, on the other hand, will probably preserve the internal bone structure. Skip to content Technology. Deep coverings of sediments decaying plant organisms organisms with hard parts soil with high mineral content.

Answer from: lasardia. Another question on Geography. Tides are caused by a differences in the gravitational force of the sun at different points on earth. In the middle east, a blank is a dry riverbed that often fills briefly with water after strong rains. Differences in courtship or other behaviors prevent mating Sarah had 7. How many pints is left. How do I do this problem Most peas in the market are green.

The angle of elevation from a viewer to the top of a flagpole is 50 degrees.