what is a fossil?
A fossil is described as any preserved evidence or remains of livings things. A fossil must be formed naturally, must be preserved remains or traces buried in rocks in the outer crust, and must be from "ancient geologic" times (over 10,000 years).
For a fossil to form, it must have hard parts, be buried quickly, and be protected from scavengers.
The Fossil Record gives clues to past life on Earth, species that have gone extinct, how species have changed over time, and when new species have appeared.
For a fossil to form, it must have hard parts, be buried quickly, and be protected from scavengers.
The Fossil Record gives clues to past life on Earth, species that have gone extinct, how species have changed over time, and when new species have appeared.
types of Fossils
There are different types of fossils depending on the organism and how it is buried and preserved.
mold fossils
Sediments bury an organism and turn into rock, leaving a cavity in the shape of the fossil. Mold fossils "go in to the rock."
cast fossils
When a mold is filled with sand or mud that hardens into the shape of the organism. Cast fossils "stick out of the rock".
Petrified (Permineralized) Fossils
Minerals soak into the buried remains, replacing and changing them into rock.
preserved Fossils
Entire organisms or parts of an organism are prevented from decaying by being trapped in ice, rock, tar, or amber.
carbonized Fossils
Leaves, stems, flowers, or fish, are pressed between layers of soft mud or clay that hardens, squeezing almost all the decaying organism away, leaving a carbon imprint in the rock
trace fossils
Considered the "remains of activity", when mud or sand hardens to stone where a footprint, trail, or burrow was left behind