| A | B |
|---|
| Sedimentary rock contains | most fossil evidence. |
| Law of Superposition | A general law stating that the rock layers on the bottom have been there the longest, therefore they are the oldest, and the one's above them are younger. |
| Unconformity | A layer of rock erased by weathering and erosion. |
| Fossils | Grouped based on how they are formed. |
| Mold Fossil | Forms when sediments bury an organism and the sediments are compacted into rock; the organism decays leaving a cavity in the shape of the organism. (The pan) |
| Cast Fossil | Forms when a mold is filled with sand or mud or other sediment that hardens into the shape of the organism. (The cake) |
| Petrified Fossils are also known as | Permineralized Fossils. |
| Petrified Fossil | Forms when minerals dissolved in a solution soak into the buried remains of an organism, replace the remains, and end up creating a "rock replica", a mineral copy of the organism. |
| Preserved fossil / original remains | Forms when entire organisms or parts of organisms are prevented from decaying by being trapped in rock (such as volcanic ash), 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 print on the rock. |
| Trace fossil | Gives clues as to the activities of an organism; forms when the mud or sand hardens to stone where a footprint, trail, or burrow of an organism was left behind. |
| There are variations among | species of similar populations |
| Organisms of a species differ from one another in | many of their traits |
| Gene mutation can cause | variation in a trait |
| An adaptation is | a trait or behavior that helps an organism survive and reproduce |
| Natural selection is | the process that explains this survival and shows how species can change over time. |
| An example of natural selection is | certain traits or adaptations involving color, camouflage, food gathering (beaks, claws) and other physical traits, sensory abilities, or behaviors enhance the survival of a species. |
| Populations in a particular environment that are better adapted to living conditions are | able to meet their survival needs and are more likely to survive and reproduce offspring with those same traits. |
| A fossil is | the preserved remains or traces of an organism that lived in the past, usually more that 10,000 years ago |
| Fossils give | clues to the diversity of living things over the history of Earth, give clues to past climate and surface changes on Earth, and give clues to changes that have occurred with organisms over time. |
| Changes in life forms, additions and extinctions, are often accompanied by | changes in environmental conditions on Earth |
| Environmental changes have been influenced by | the impact of an asteroid or comet, climatic changes, and volcanic activity. |
| Scientists hypothesize that possibly | a large asteroid or comet impacted with Earth and caused dust and smoke to rise into the atmosphere and cause climatic changes, as well as the dying of many forms of plant life and animals that depended on those plants for food. |
| Eras are divided into | periods |
| Periods are divided into | epoches |
| Geologists divide the time between Precambrian and the present into three long units called | eras, from oldest to most recent, Paleozoic, Mesozoic, Cenozoic |
| Present day Earth is in the | Cenozoic era and the Quaternary period in the Holocene epoch. |
| The geologic time scale is | a record of the major events and diversity of life forms in Earth’s history. |
| 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. |
| Paleozoic Era; | Early land plants included simple mosses, ferns, and then cone-bearing plants. |
| Paleozoic Era; | By the end of the era, seed plants were common. |
| Paleozoic Era; | 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. |
| Mesozoic Era; | Small mammals and birds also appeared |
| Mesozoic Era; | Toward the end of the era, flowering plants appeared and the kinds of mammals increased. |
| Mesozoic Era; | The mass extinction that ended the era caused the dinosaurs to become extinct |
| Cenozoic Era; | New mammals appeared while others became extinct. |
| Cenozoic Era; | The diversity of life forms increased. |
| Cenozoic Era; | Flowering plants became most common. |
| Cenozoic Era; | Humans are also part of the most recent period of this era. |
| Relative age means | Relative age means the age of one object compared to the age of another object. |
| Relative age does not | tell the exact age of an object. |
| The relative age of rocks and fossils can be determined using two basic methods: | ordering of rock layers and index fossils |
| Absolute age means | determining the number of years since the object was formed |
| The absolute age of igneous rocks can | be determined using radioactive decay |
| The law of superposition states that | each rock layer is older than the one above it |
| To be an index fossil | the organism must have lived for a brief period of time and all over the world. |
| A species is extinct if | no members of that species are still alive. |
| Natural factors can cause | extinctions such as has happened throughout Earth history. |
