Evolution of Landforms Mold fossil – forms when sediments bury an organism and the sediments change into rock; the organism decays leaving a cavity in the shape of the organism. Cast fossil – forms when a mold is filled with sand or mud that hardens into the shape of the organism. Petrified fossil (permineralized fossil) – forms when minerals soak into the buried remains, replacing the remains, and changing them into rock. Preserved fossil – forms when entire organisms or parts of organisms are prevented from decaying by being trapped in rock, ice, tar, or amber. Carbonized fossil – forms when organisms or parts, like leaves, stems, flowers, fish, are pressed between layers of soft mud or clay that hardens squeezing almost all the decaying organism away leaving the carbon imprint in the rock. Trace fossil – forms when the mud or sand hardens into stone where a footprint, trail, or burrow of an organism was left behind. Precambrian Era
The Precambrian Era is Earth's first era of time. It began with the creation of the Earth around 4.6 billion years ago.
5 major events occurred during this era: (1) the formation of the Sun and light, (2) the creation of the Earth, (3) the creation of the atmosphere through volcanic out-gassing, (4) the creation of the oceans, and (5) the creation of life.
Began with simple life forms such as bacteria and simple algae.
There was a rise of simple organisms such as jellyfish and sea worms by the end of the era.
Few fossils because the life forms were soft-bodied and had no hard skeleton.
Paleozoic Era
Began with the early invertebrates, such as trilobites and brachiopods; continued to develop early vertebrate fish, then arachnids and insects; later came the first amphibians, and near the era’s end the reptiles became dominant.
Early land plants included simple mosses, ferns, and then cone-bearing plants.
By the end of the era, seed plants were common.
The mass extinction that ended the era caused most marine invertebrates as well as amphibians to disappear.
Mesozoic Era
Reptiles were the dominant animals of this era, including the various dinosaurs.
Small mammals and birds also appeared.
Toward the end of the era, flowering plants appeared and the kinds of mammals increased.
The mass extinction that ended the era caused the dinosaurs to become extinct.
Cenozoic Era
New mammals appeared while others became extinct.
The diversity of life forms increased.
Flowering plants became most common.
Humans are also part of the most recent period of this era.
Absolute (radioactive) Dating - measurement of the known rates of decay of radioactive materials that an object contains in order to determine the age of the object Law of Superposition - states that in undisturbed rock layers that newer layer will be deposited over older layers Law of Crosscutting Relationships - states rock layers that cut across other rock layers are younger than those they cut Relative Dating - determining the age or order of things from the past or past events without knowing or calculating the actual age Sedimentary rock - rock formed by deposition of sand, clay and other pieces of rock that are compacted together under pressure Uranium - radioactive heavy metal that is an abundant source of nuclear energy that has 14 known isotopes used in radioactive dating Fault - fracture along which blocks of the Earth's crust that can be caused by the shifting or dislodging of the Earth's crust. Types include normal, strike slip, or reverse Geology - the study of the rocks, processes, and history of Earth Geologic Time Scale - system of chronological measurement that relate to the history of events in Earth's past, consisting of fossils and major events. Ice Core - a core sample of ice removed from a sheet of ice. Properties of the ice and the crystallized components in the ice are used to reconstruct climatic record Igneous rocks - type of rock formed under or above ground when magma or lava cools Metamorphic rock - rock created from the transformation of other types of rock through heat and pressure
Evolution of Life Forms Adaptation: a trait that increases the chances that an organism will survive and reproduce Analogous structures: similar structures that evolved independently in two living organisms to serve the same purpose. Artificial selection: the breeding of plants and animals with desired traits to attempt to produce offspring with these same traits. Biological evolution: the change over time of living organisms Darwin: was a naturalist who proposed and provided scientific evidence that all species of life have evolved over time from common ancestors through the process he called natural selection. Evolution: the change in population of a species over time. Extinction: The evolutionary termination of a species caused by the failure to reproduce and the death of all remaining members of the species; the natural failure to adapt to environmental change. Fossil: evidence of past life preserved in rock. Fossil record: the complete body of fossils that shows how species and ecosystems change over time. Fossilized: the process of becoming a fossil Homologous structures: organs or skeletal elements of animals and organisms that, by virtue of their similarity, suggest their connection to a common ancestor Index fossil: a fossil found in a narrow time range but widely distributed around the earth; used to date rock layers Mutation: a random change to a gene that results in a new trait Natural selection: survival of the fittest organisms that are the best adapted to their environment and the ones that will live long enough to reproduce and pass on their favorable adaptations Species: the most specific classification of living things Speciation: the process of natural selection producing a new species out of existing species over thousands or millions of years. Theory: an explanation that ties together many hypothesis and observations. Trace fossil: a fossilized mark that is formed in soft sediment by the movement or actions of an animal. Trilobite: a marine organism that is an example of an index fossil