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Life on Earth
Ch8 Test: Geologic Time Scale
| Question | Answer |
|---|---|
| Earth’s history is recorded on a time line called the ___ ___ ___. | geologic time scale |
| Paleontologists divide units of time using __ __ selected by certain criteria. | index fossils |
| Index fossils must have ___ ___, so they are preserved easily. | hard parts |
| Index Fossils must be geographically ____, so they are easily found | widespread |
| Index fossils must have lived in many ____, so as to be preserved in many rock types. | environments |
| Index fossils must become ____ after a short period, so that small units can be established. | extinct |
| The divisions of the geologic time scale are eons, eras, periods, and ____ | epochs |
| ___ are the largest divisions and represent the longest time periods | Eons |
| The Phanerozoic Eon is divided into three ____: Paleozoic, Mesozoic, and Cenozoic | eras |
| The Cenozoic Era is divided into the Paleogene, Neogene, and Quaternary _____. | periods |
| A ___ ___ is the dying off of many different species during a short geologic time period. | mass extinction |
| ___ percent of all species that ever lived are now extinct | Ninety-nine |
| Mass extinctions can happen over a period of several ___ years | million |
| A ___ ___ causes a drastic change in the numbers of organisms over a short period of time. | catastrophic event |
| There is evidence that ___ ___(global warming or cooling) has caused some mass extinctions, including those ending the Devonian and Ordovician periods. | climate change |
| Global warming is linked to ___ ___, such as carbon dioxide, in the atmosphere | greenhouse gases |
| ___ ___ can cause can cause oxygen levels in water to decrease and sea levels torise. | Global warming |
| ___ ___ could lower sea levels and decrease warm, shallow-water environments | Global cooling |
| ___ can contribute to mass extinctions by emitting dust, ash, lava, and gases that can affect climate and organisms | Volcanoes |
| The 1902 eruption of Mt. Pelee produced a cloud of dust and gas that caused worldwide___. | cooling |
| The mass extinction ending the ___ period is attributed to volcanic eruption | Cretaceous |
| ___ ___, including the Siberian and Deccan Traps, may have caused mass extinctions | Basalt flows |
| ___ ___ can cause climate change by blocking the Sun’s rays | Volcanic haze |
| An ___ impact is thought to have contributed to the Cretaceous mass extinction | asteroid |
| The impact could shroud the Earth in sun-blocking dust and haze, lowering temperaturesand inhibiting ___. | photosynthesis |
| ___ time represents 88 percent of Earth’s history | Precambrian |
| ___ in adjacent rock layers are more similar than fossils in widely separated layers | Fossils |
| The more ___ a fossil was formed, the more it resembles a living organism | recently |
| Precambrian time is divided into three ___: Hadean, Archean, and Proterozoic | eons |
| Most Precambrian rock is ___, so it is more difficult to date. | metamorphosed |
| Precambrian atmosphere had very little ___ and no ozone layer | oxygen |
| Ancient ___ contain fossils of Earth’s earliest known organisms | stromatolites |
| Stromatolites are composed of alternating layers of sediments and ___ | cyanobacteria |
| ___ are single-celled,photosynthetic blue-green algae | Cyanobacteria |
| Cyanobacteria released ___ into the atmosphere through photosynthesis | oxygen |
| ___ ___ began to favor organisms that used oxygen | Natural selection |
| An ___ ___ developed to shield Earth from ultraviolet rays | ozone layer |
| More complex, soft-bodied organisms, called ___ ___, evolved | Ediacaran fauna |
| Organisms with hard parts evolved during the ___ Era | Paleozoic |
| During the ___ explosion, shelled animals and other invertebrates greatly increased in number and diversity. | Cambrian |
| ___ were the most commonly fossilized organisms of the Cambrian Period | Trilobites |
| Invertebrates, such as corals and brachiopods, evolved, as did ___ | insects |
| Vertebrates evolved during the ___ Era, many of which lived in oceans | Paleozoic |
| One group of bony fish evolved into modern fish; the other evolved into ___ | amphibians |
| ___, which lay watertight eggs, allowed organisms to spread into drier habitats | Amniotes |
| Plants developed ___ systems, allowing them to spread onto land | vascular |
| ___ ___, ferns, and pine trees appeared during the Mississippian and PennsylvanianPeriods | Club mosses |
| Club mosses, ferns, and pine trees became large ___ deposits used as an energy resource today | coal |
| ___ ___ occurred during the Ordovician, Devonian, and Permian Periods | Mass extinctions |
| The late ___ extinction ended the Paleozoic era, with the extinction of 90 percent of marine species and 70 percent of land pecies. | Permian |
| Two causes of the Permian extinction are the uplifting of ___ and the emission of ash and sulfur from theSiberian Traps. | Pangaea |
| The ___ Era includes the Triassic, Jurassic, and Cretaceous Periods | Mesozoic |
| Algae, ___, stromatolite organisms, and reef-building corals evolved during the Mesozoic Era | clams |
| Ocean vertebrates included predatory reptiles; land vertebrates included frogs, crocodiles, ___, and dinosaurs | pterosaurs |
| ___ evolved from small to larger species, including the Apatosaurus | Dinosaurs |
| Scientists originally thought dinosaurs were ___-___, but they now believe dinosaurs’structures were more similar to those of mammals and birds | cold-blooded |
| Dinosaurs became ___ at the end of the Cretaceous Period | extinct |
| ___ was a dinosaurlike animal believed to be an ancestor of birds | Archaeopteryx |
| ___ evolved in the Triassic Period alongside the dinosaurs | Mammals |
| As dinosaurs became extinct, mammals moved into their ___ | niches |
| ___, plants with seeds but no flowers, dominated the Mesozoic Era | Gymnosperms |
| ___, flowering plants, appeared near the end of the Mesozoic Era | Angiosperms |
| Mass extinctions occurred at the end of the ___, Jurassic, and Cretaceous Periods | Triassic |
| The current era, the ___, is divided into seven epochs | Cenozoic |
| Modern mammals, including modern whales and ___, evolved | primates |
| Primates have opposable ___ and two eyes that look forward | thumbs |
| About 4.4 million years ago, the ___, the group that includes homo sapiens, evolved | hominids |
| ___ plants increased and diversified into the more than 250,000 species that exist today | Flowering |
| Extinctions in the Cenozoic Era have occurred by natural selection and due to ___ causes | human |
Created by:
jnosik
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