Vocab
evidence of life from the past, such as fossilized bones, footprints, or leaf prints
fossil
a type of fossil formed when a thin layer of carbon from an organism is left behind on rock
carbon film fossil
An igneous intrusion is found cutting through Layers X, Y, and Z. What is the youngest feature?
the intrusion
He is the scientist most famous for explaining evolution by natural selection.
Charles Darwin
a method used to determine the exact age of a rock, fossil, or event in years, often using techniques like radiometric dating based on the decay of radioactive elements
absolute dating
having died out completely and no longer alive anywhere on Earth
extinct
a hollow impression left in rock where an organism once was and is later filled with minerals that harden into the shape of the original organism
mold and cast fossil
A fossil is found in both Layers H and J. If Layer J is below Layer H, which layer is older?
layer H
When a population is separated and evolves into two different species, this happens.
speciation
a fossil has 50% of uranium - 238 remaining. How many years has it been since this organism was alive?
4500
the process by which species adapt to environmental changes over a very long time
evolution
evidence of an organism’s activity, such as footprints, burrows, or trails, rather than the preserved body of the organism itself
trace fossil
magma that cools and hardens beneath the surface, making it younger than the rock layers they cut through or lie on
intrusion
the geologic timescale is broken into ____s and _______s. (e.g., Mesozoic & Triassic)
eras & periods
a fossil has 5% of uranium - 238 remaining. How many years has it been since this organism was alive?
18000
a scientist who studies fossils in order to understand the ancient history of life on Earth
paleontologist
Example of the type of material a preserved fossil could be in
sap, tar, ice, amber
what we call lava from a volcanic eruption cools on top of rock layers
extrusions
This record, found in layers of sedimentary rock, shows how life has changed over time.
the fossil record
a fossil has 12% of uranium - 238 remaining. How many years has it been since this organism was alive?
13500
a body structure in two or more species that features the same parts (for example, the same bones)
shared structure (homologous structure)
when minerals slowly replace all or part of an organism, turning it into stone while preserving its original structure
petrified fossil
this law states that in undisturbed rock layers, the oldest rocks are at the bottom and the youngest are at the top.
law of superposition
These structures no longer have a function but show evidence of evolution, like appendix.
vestigial structures
This is the name for the time it takes for half of a radioactive element to decay.
half life