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Dino Bio: fossilization, dating, geologic time

Terms

undefined, object
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fossil
any trace of past life
igneous rock
formed when hot, liquid rock cools (either magma or lava)
metamorphic rock
forms below the surface of the Earth, under conditions of high temperature and pressure; it's always denser than before
sedimentary rock
forms at or near the surface of the Earth under normal temperature and pressure
formation of sedimentary rock
process: erosion, transport, deposition, lithification
rock cycle
any rock can be transformed into any other rock
sedimentary structures
traces showing environment in which sedimentary rock formed: ripple marks, mud cracks, sole markings
Principle of Superposition
in any undisturbed sequence of sediment, the oldest will be on the bottom
Principle of Uniformitarianism
"the present is the key to the past"
Principle of Faunal Succession
certain animals are time and place specific
fossil record
history of preserved life in a rock
fossils are biased
only hard parts are fossilized (bone); fossilization favors animals from depositional environments; small, fragile animals aren't preserved as much
still might not be preservation
sediment might not lithify
where to find fossils
look for exposed bone in layers of sediment; look for certain dinosaurs in rocks of a certain age
permineralization
water carrying minerals comes through the sediment, filling holes in the bones with the minerals
petrification/replacement
organic material in the bone dissolves and is replaced by minerals
soft-structure preservation
(incl. eggs) {freezing, drying, pickling and tanning (peat bogs)}, amber, and tar. {only recent fossils: past 20 thous years}
mold
negative impression
cast
if the mold gets filled in and preserved
trackways
fossilized footprints
gastroliths
fossilized stomach stones: from gizzards (chickens and sauropods)
coprolites
fossilized feces; shows size, diet, and environmental details
what we do/don't know
do: size, morphology, time period, location, diet, synapomorphies, ecology, and behavior; don't: color, sounds, and social interactions
what are we dating?
the rock, not the fossil
relative dating
age in relation to something else
biostratigraphy
finding sequences of fossils in rocks (with superposition and faunal succession)
absolute dating
gives dates in years
tree-ring dating
only recent things
carbon-14 dating
organic material, but only up to 20-30 thous years old
radiometric dating method
date igneous rock through radioactive decay (half-life)(because igneous sets half-life at zero)
eras
{Cenozoic, Mesozoic, Paleozoic}, Precambrian; {Phanerozoic}
Cenozoic Era
65 million years to current
Mesozoic
245 million years to 65 million years; Cretaceous, Jurassic, Triassic
Paleozoic
570 million years to 245 million years

Deck Info

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justinabyrne

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