Fossils and Time Scale Flashcards
Fossils
The natural remains or traces of past life. Something is considered to be a fossil if it is at least 10,000 years old
Fossil record
All of the fossils that have existed throughout life’s history, whether they have been found or not
Geologic Maps
Geological maps help paleontologists find the right rocks for their question
Groundwater
Water found underground us a result of rainfall, ice and snow melt, submerged rivers, lakes, springs
Ichnology
The study of trace fossils
Igneous rock
Type of rock produced when molten magma (lava) cools and solidifies
Impression
Fossilized prints or marks made by a living thing. Leaf prints, skin prints and footprints are a good example
Inorganic
Not containing carbon. Not from living things. Ex., mineral
Intertidal
the coastal zone between the low and high tide mark where the waves impact the land
Macroscopic
Objects or organisms that are large enough to be seen with the naked eye
Metamorphic rock
Rocks produced when any type of rock is changed by heat, pressure, and chemical activity in the Earth
Microscopic
Objects or organisms that are too small to be seen with the naked eye
Mineralization
The process whereby living material is replaced with minerals
Mold
The impression of an organism left behind in the rock
Organic
containing carbon. Also refers to characteristic features of living things
paleontology
the study of life in the past
Paleontologists
People who study fossils and other types of evidence to learn abt life in the past
Plate tectonics
The concept that explains the movement of the Earth’s crustal plates, sea floor spreading, and a number of other geologic processes of the Earth’s surface
Permineralized
Fossilization process that occurs when minerals, carried by groundwater, enter and harden in the posters of an organism’s structures.
Replacement
Fossilization process that occurs when an organism is completely decomposed and replaced by minerals.
Scavenger
An organism that feeds on dead and dying organisms.
Sedimentary rock
Rock that is formed when layers of small particles (sediment) are compressed and cemented together
Uplift
The process that causes part of the earth’s crust to rise above surrounding areas. This can cause layers of rock to become exposed at the surface.
Name five kinds of trace fossils
Burrows, trails, tracks, feces, and footprints are five types of trace fossils.
How are the mouse and jellyfish being compared?
The mouse and the jellyfish are being compared in order to explain how hard parts, such as bones and teeth, are more readily preserved in the fossil record than soft tissue. A mouse is most likely to become a fossil because they have harder bodies with more bones, while the jellyfish don’t have bones.
What are two reasons why many organisms never become part of the fossil record?
There are very different conditions that the animals die in and that can impact whether they become a fossil or not. There are a lot of ways that a fossil can be destroyed that only very few can resist it long enough to become a fossil.
What are two ways that geologic processes can destroy a fossil?
Fossils can be moved by streams, glaciers, or scavengers. They can also be eroded by wind, water, and sun.
Why isn’t igneous rock a good place to look for fossils?
You might not find a fossil in an igneous rock because any organism caught in the lava flow would get destroyed because of the extremely high temperatures.
What are fossils?
The preserved remains, imprints, traces or evidence of ancient, prehistoric living things organisms. Tells when, where and how organisms lived.
Prehistoric
Before history was wirtten
What is the fossil record described as and why?
Jigsaw puzzle with most of the pieces missing. because they keep us guessing about their color, sounds, and most of their behavior.
What rock type are nearly all fossils found in?
Sedimentary rocks.
What exposes the fossil at the surface?
Weathering and erosion
What clue do fossils give us?
What living things existed in the past? How living organisms have changed over time? what ecosystems and environments were like.
Catastrophism
Idea that conditions & organisms on Earth change in quick, violent events. Scientists disagreed with this idea bc Earth’s history is full of violent events
Uniformitarianism
Geologic processes that occur today are similar to those that have occurred in the past. “The present is key to the past” James Hutton came up with this. the landscapes that changed were slow, it took more than a few thousand years to form the layers of rock around him & to erode mountains
Why do we study fossils?
help determine the absolute and relative ages of rocks. Provide clues to past geologic events, climates, and evolution of living things. Are an indicator of an area’s ancient environmental conditions and climates.
Best conditions for fossils to form
Quick burial in moist sediments. Quick burial in volcanic ash. Presence of hard body or plant parts. Consistent temperatures. Lots of minerals in groundwater. very fine sediments. clam conditions.
2 types of fossil preservation
Body fossil and Trace fossils
Body fossils
The remains of part (or all) of an actual organism.
Trace fossils
Traces or marks left behind by an organism. They show an organism was there, but aren’t the actual organism. Can tell size, weight, age, social behavior.
Different ways that body fossils can be preserved
Permineralized remains, Carbon films, coals, molds and casts, original remains
Different ways that trace fossils can be preserved
tracks, trails, burrows
Permineralized remains
when minerals fill small holes in hard parts like bone, teeth, and shells. Water flows over buried fossil, dissolves fossil and fills the space with minerals in groundwater. The minerals replace the remains, changing them into rock. some can even encase the original genetic material.
Carbon films
When organisms or parts are pressed between layers of mud or clay. The mud or clay hardens squeezing almost all of the decaying organism away. Sediment buries the dead organism, as sediment piles up heat and pressure force liquids out of the organism’s tissues, leaving carbon imprint behind.
Coals
Plant matter accumulated and buried then carbonized forming coal. Since plant structure is usually lost there is not not much revealed about the plant
Molds
Rock has pore space & allows water to flow through decaying the organism & leaving behind a cavity in the shape of the organism
Casts
Mineral – rich water flows through mold & fills cavity producing a copy of the organism
Original Remain
Soft parts can be preserved in Amber (Sticky tree resin), Ice, tar.
Trails and Burrow
Tunnels have been left behind by burrowing organisms
Relative age
the game of something in comparison to the ages of other things
How do geologists determine the relative age of rocks an other structures?
Examining their places in a sequence.
Principle of superposition
In undisturbed layers of rock the oldest rocks are on the bottom and the rocks become progressively younger toward the top.
Lateral continuity
When the sediments are deposited in large, continuous sheets in all lateral directions, but then out / meet a barrier. Ex) River may erode but the placements do not change
Principle of original Horizontality
Most rock forming sediments are deposited in horizontal layers. Layers can be deformed
Inclusions
When a piece of an older rock becomes part of a new rock. If one rock contains pieces of another rock, the rock containing the pieces is younger than the pieces.
Cross-cutting relationships
When forces within Earth cause rock formations to break or feature. If one feature cuts across another feature, the feature that it cuts across is older.
Faults
When rocks move along a fracture line
Unconformities
Surface where rock has eroded away and younger rocks have been deposited, producing a break of gap in the rock record on a few hundred to billions of year.
Disconformity
Gaps in the rock record. When sedimentary rocks form and then get eroded and younger rocks are deposited on top.
Angular Uncomformity
When sedimentary rocks are tilted and eroded and new sedimentary rocks are laid on top.
Nonconformity
Sedimentary rocks deposited on top of igneous or metamorphic rock layers. The layers may be eroded.
What are the possible causes of Uncomformities?
Uplift, weathering and erosion, and subsidence (sinking of land)
Correlation/connection
Rocks and fossils from separate areas may be related if they are part of the same layer
Index fossils
Fossils of organisms that existed on earth for a short period of time. Were abundant and widespread geographically.
Estimated age
Scientists determine this by looking at multiple index fossils and seeing when they match up. The scientists then have a range of years that say from which year to this year the rock was formed.
Radioactive decay
occurs when the nucleus of a radioactive atom spontaneously transforms into an atomic nucleus of a different, more stable isotope
Radiometric dating
By measuring the ratio of parent isotope to daughter products, one can determine the absolute age of a rock.
What element can be used to date organisms less than 75,000 years old?
Carbon-14
What type of rocks does radiometric dating help date?
Igneous and metamorphic rock. Not sedimentary
Relative dating
uses geologic sequences of events by comparing rock layers, but cannot tell how long ago the events occurred.
Absolute dating
Uses radioactive decay. geologists determine absolute ages by using properties of the atoms that make up materials.
What are the four major subdivisions of the geological time scale?
In order from biggest to smallest: Eon (divided into eras), Era (divided into periods), Period (divided into epochs), and Epoch
Geological time scale
A record of the life forms and geologic events in earth’s history
Geologic column
Scientists place Earth’s rocks in order by relative age
Precambrian time
Name given to the earliest span of time in earth’s history. Makes up nearly 90% of earth’s history
Hadean Eon
Rocks from meteorites and moon
Archean Eon
earliest rocks on earth
Proterozoic Eon
Organisms with well developed cells
Phanerozoic Eon
Means visible life. Well represented in the fossil record
What periods is the Phanerozoic era divided into?
In order: Paleozoic, Mesozoic, Cenozoic
What marks the end of an Era?
A mass extinction
Periods in the Paleozoic era
In order: Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, Permian
Cambrian Period
Cambrian explosion. 1st trilobites
Silurian Period
1st land plants
Ordovician Period
1st inverdibrates
Devonian period
Age of fish. When fish flourished
Mississippian period
winged insects
Pennsylvanian Period
First reptiles
Permian Period
Age of amphibians. When they flourished
Early Paleozic
The Cambrian Explosion = “Age of Invertebrates”. lived in the ocean and had no backbones. Ended with mass extinction.
Middle Paleozoic
“Age of fish”. Animals with backbones evolved. On land, cockroaches, dragonflies & insects evolved. Earth’s 1st plants appeared, they were small & lived in water. Continents collided. Appalachian mountains formed. Ended with mass extinction.
Late paleozoic
“Age of Amphibians”. Amphibians adapted to land-had lungs, could breath air, thick skin slowed moisture loss. Strong limbs let them move around on land, but they did go back to the water to lay eggs. Reptiles evolved. Did not need water for reproduction. It’s eggs have rough, leathery shells that protect them from drying out. Coal swamps during the Carboniferous & Permian Periods became our major source of coal we use today.
Continental collisions formed a giant supercontinent called Pangaea. Coal dried up, climate became cooler. Carboniferous period is the Mississippian Period & Pennsylvanian Periods combined.
Permian mass extinction
Large mass extinction. 95% of marine life & 70% of all life on land became extinct. Maybe Pangaea decreased the amount of space where marine mammals could live.
Ocean currents made the center of Pangaea drier. A large meteorite or a massive volcanic eruption could’ve impacted climate change-reducing sunlight, reducing temperature and collapsing the food web.
Periods in the Mesozoic era
Triassic, Jurassic, Cretaceous
Triassic Period
First dinosaurs/ small mammals
Jurassic period
First birds/flowering plants
Angiosperms
Plants with flowers and seeds enclosed in their fruit
Gymnosperms
Plants with cones, no flowers or fruits. Have naked, no protective covering seeds on the surface of their leaves.
Cretaceous period
Dinosaurs flourished.
Mesozoic era climate
warmer than Paleozoic era
Mesozoic era
Mammals evolved and remained small in size. Other animals adapted to lush tropical forests and warm ocean water. Oceans had more water bc there were no ice caps or glaciers. Narrow channels grew larger as the continents moved apart. The channels became oceans. Sea level rose, evaporated & massive salt deposits were left behind. The Rocky Mountain formed during this time.
Cretaceous mass extinction
Due to large meteorite or volcanic eruption. Added extra dust, no sunlight, killed plants and animals.
Periods in the Cenozoic era
Tertiary, Quaternary
Tertiary Period
Mammals thrive
Quaternary Period
Age of man/technology
Mountain building in the Cenozoic Era
India crashed into asia making the Himalayas. Africa pushed into Europe, forming the Alps. Rocky mountains continued to form in the west coast of North America. The Cascade & the Sierra Nevadas formed on the West coast. On the east coast the Appalachian Mountains continue to erode.
Ice Age
Happened during the Pleistocene Epoch. When a large proportion of Earth;s surface is covered by glaciers.
Which Era has the most complete fossil record?
Cenozoic era.
When are we living?
Phanerozoic Eon, Cenozoic era, Quaternary period, Holocene epoch
What caused the mass extinction of Precambrian time?
Glaciation events (Ice ages)
what caused the mass extinction of the Paleozoic Era?
Volcanic activity, climate changes, lowering of sea levels
What caused he mass extinction of the Mesozoic Era?
Asteroid, comets, and meteor collided with earth
What animals lived during the Mesozoic era?
Dinosaurs, birds, small mammals, and reptiles.
What types of fossils were found from Precambrian time?
Trace fossils; Rare fossils of multicellular life forms are from soft-bodied organisms different from today.
Would Precambrian time have a lot of fossils?
No, because soft bodied animals do not leave a lot of fossils
Paleozoic is known as the age of
Invertebrates or trilobites (Early paleozoic)/ Fish (Middle Paleozoic)/ amphibians (Late Paleozoic).
Cenozoic is known as the age of
Mammals
Mesozoic is known as the age of
Dinosaurs or reptiles
What can cause the rock layers to not be horizontal?
Earthquakes, mountain building
Requirements to be an index fossil
Widespread (The fossils must show up in each column), abundant, short-lived (within each, the fossil can only appear in one layer/row).
Ho do scientists match up rock layers?
rock layers are exposed only where rivers have cut through overlying layers of rock and sediment. Same type of fossils were found in layers- good indication was one continuous deposit
What are some slow, everyday processes?
Plate movement, glaciers, ice age, changes in atmosphere/weather
What are some violent and unusual events?
Meteor, earthquakes, volcano, extreme water.
What is the meaning of the Cenozoic era?
Recent life
What is the meaning of the Mesozoic era?
Middle life
What is the meaning of the Paleozoic era?
Ancient life
Meaning of the Pre-archean Eon
Time before the Archean
Meaning of the Archean Eon
Original or ancient
Meaning of the Proterozoic Eon
Before animal life
