Geological Time Scale and Fossils

Flashcard maker : Ruth Blanco
Precambrian
Name for the time in earths early history that accounts for ninety percent of earth’s time, but only cellular organisms lived.
Paleozoic Era
the part of geologic time 570-245 million years ago ; invertebrates, fishes, amphibians, reptiles, ferns, and cone-bearing trees were dominant
Mesozoic Era
middle life (245-144 million years ago); rise of mammals and dinosaurs; the rise of birds; extinction of dinosaurs, rise of flowering plants
Cenezoic Era
Era of recent that began about 66 MYA, and continues today. Includes the first appearance and homo sapiens about 400,000 years ago
Earth’s Periods
The unit of time that comes after era.
Earth’s Epochs
The unit of time that comes after period.
Relative Dating
Method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock
Law of Superposition
The geologic principle that states that in horizontal layers of sedimentary rock, each layer is older than the layer above it and younger than the layer below it.
Index Fossil
a fossil known to have lived in a particular geologic age that can be used to date the rock layer in which it is found
Trace Fossil
a fossil of a footprint, trail, burrow, or other trace of an animal rather than of the animal itself.
Mold Fossil
a space in a rock that has the shape of the remains of a living thing that once occupied that space.
Cast Fossil
a model in the shape of a living thing or its remains, it forms when minerals or rock particles fill the space
Carbonized Fossil
Forms when entire organisms or parts, like leaves, stems, flowers, fish, are pressed between layers of soft mud or clay
Preserved Fossil
forms when entire organisms or parts of organisms are prevented from decaying by being trapped in rock, ice, tar, or amber.
Petrified Fossil
a fossil in which minerals replace all or part of an organism
Strata
layers of rock
Fossil Record
Chronological collection of life’s remains in sedimentary rock layers
Extinction
The disappearance of all members of a species from Earth

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