Studied by 56 peopleSedimentary Rock
The place most fossils form
Permineralization
The process in which minerals carried by water are deposited around a hard surface, creating a fossil
A natural cast or impression
Flowing water removes all the original tissue, forming this
Trace Fossils
Fossils showing the activity of an organism, like footprints
Amber-Preserved Fossils
Fossils trapped in tree resin that hardens after the tree is buried
Preserved Remains
The fossil forming when an organism becomes encased in a material like ice
Relative Dating
Estimating the time an organism lived
Compare the placement of fossils in layers of rock
The way scientists estimate fossil age using relative dating
Radiometric Dating
The process of using unstable isotopes to estimate the age of an organism
Isotopes
Atoms that differ in the number of neurons that decay over time
Half-Life
The amount of time it takes for half of the isotope to decay & be replaced
Eras
Periods of time lasting tens to hundreds of millions of years
Period
Each era consists of two or more of these
Epochs
Periods of time lasting several million years
Mass Extinctions or Explosive Radiations
How scientists determine when a new time period occurs on the Geologic Time Scale
3.8 billion years ago
The first organisms appeared at this time
Prokaryotic
The first organisms were _______
Endosymbiosis
The first eukaryotic cells evolved through this process
A bacteria another cell absorbed
The first mitochondria evolved from this
Genetic Variation
The biggest advantage of sexual reproduction
Paleozoic Era
The era in which multicellular organisms appeared
Cambrian Explosion
The period in which a diversity of water animals appeared
Middle of the Paleozoic Era
Amphibious animals appeared during this period
Mesozoic Era
Reptiles radiated during this era
Mesozoic Era
The first mammals evolved during this period
Cenozoic Era
Mammals radiated during this period
Mammals, forward-facing eyes, enlarged brains, rotating arms, long lower limbs, and opposable thumbs
Characteristics of primates
Prosimians & Anthropoids
2 main groups of primates
Lemurs
An example of prosimians
Old World Monkeys, New World Monkeys, & Hominoids
Groups of anthropoids
Hominids, Great Apes, & Lesser Apes
Groups of hominoids
Big brains, thin faces, long thumbs, & bipedal
Characteristics of hominids
Australopithecus & homo
Groups of hominids
Homo Sapiens
The species name of modern humans
200,000 years ago
Modern humans evolved this long ago
Use of tools & larger brains
Characteristics of homo sapiens
Era, period, epoch
Measures of time on the geologic time scale from longest to shortest
Note
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