Types of Fossils
Age Dating
Geologic Time
Mystery
100
What type of fossil is this?
preserved remains
100
the term for dating rocks based on the characteristics of rocks around them
relative age dating
100
we currently live in the ____________ era
cenozoic
100
when is an organism more likely to become a fossil
if it has hard parts and is buried quickly
200
preserved evidence or activity of an organism is known as
trace fossil
200
the law that states that in undisturbed rock layers, the oldest layer is at the bottom
law of superposition
200
this era is punctuated by the formation of the supercontinent Pangea, had a rapid development of life, and there was a mass extinction at the end of this era
paleozoic
200
true or false: we divide eras of geologic time based on how long that era lasted
false: based on mass extinctions or explosions of new life
300
true or false: petrified wood is preserved remains, and is still made of the same wood it was before
false, it is an example of mineral replacement
300
The inclusions in rock B are ______ than rock B
older
300
describe the main characteristics of the precambrian era
longest era, simple unicellular life, marks the beginning of earth
300
dinosaurs were dominant in the ____________ era
mesozoic
400
these fossils were found in abundance in similar layers of rock around the world and can be used to date the age of rocks around them
index fossils
400
Why is the ammonite considered a good index fossil?
It is found in only one layer and in abundance
400
horseshoe crabs evolved beginning in which era
paleozoic
400
name two fossils from our fossil labs that still exist today
coral, brachiopods, gastropods, clams
500
a ____________ is an imprint left behind by a deceased organism but a ______________ is a copy of the imprint usually filled by rock or sand
mold, cast
500
how did scientists estimate the age of the earth? what age do they estimate it to be?
absolute dating using zircon radioactive isotopes, 4.6 billion years old
500
what major events divide the cenozoic era into its periods
ice ages
500
name a living relative of each of these three organisms: gastropod, crinoid, echinoid
snail, sea lillies or sea stars, sea urchin