Biology 6.3.5 Flashcards
What are ‘Fossils’?
Fossils are the ‘Remains’ of Organisms from Millions of Years Ago, which are Found in Rocks.
The Different Main Fossilisation Processes: (3)
-Fossils May be Formed From Parts of Organisms that have not Decayed, Because One or More of the Conditions Needed for Decay are Absent.
-When Parts of the Organism are Replaced by Minerals as they Decay.
-As Preserved Traces of Organisms, Such as Footprints, Burrows, & Rootlet Traces.
Explain the Fossilisation Process: ‘Fossils May be Formed From Parts of Organisms that have not Decayed, Because One or More of the Conditions Needed for Decay are Absent.’. (3)
-In Amber (Fossilised Tree Resin), & Tar Pits, a Lack of Oxygen & Moisture Means that Decomposers Cannot Survive there to Break Down Dead Organisms.
-In Glaciers & Permafrost Regions (Areas that Continuously Remain Frozen), it is Too Cold for Decomposers to Survive.
-Peat Bogs are Too Acidic for Decomposers to Survive.
Explain the Fossilisation Process: ‘When Parts of the Organism are Replaced by Minerals as they Decay.’. (3)
-Body Parts, Such as Teeth, Shells, & Bones, Don’t Decay Easily, & Can Last a very Long Time After the Organism has Died.
-They are Slowly Replaced by Minerals that Form a Rock-Like Substance in the Same Shape as the Original Body Part.
-They Can Often be Seen Distinctly Within the Surrounding Rock.
Explain the Fossilisation Process: ‘As Preserved Traces of Organisms, Such as Footprints, Burrows, & Rootlet Traces.’. (3)
-An Impression (eg Footprints) Can be Left in a Soft Material like Clay.
-The Impression Becomes Fixed, as the Clay Hardens.
-Sometimes, an Organism May be Buried in Clay, but Decays After the Clay has Hardened, Leaving a Cast of the Organism.
Many Early Forms of Life were ___-___, which Means that they Have Left Few Traces Behind- Soft Tissues Often ___ Fully, Leaving No Trace in the ___ ___.
Soft-Bodied, Decay, Fossil Record.
Many of the Traces Left Behind by Soft-Bodied Organisms have Mainly been Destroyed by…
Geological Activity, eg Tectonic Plate Movement May Have Crushed Fossils that Had Already Formed.
Evidence for Early Life Forms on Earth Can be Found in the…
Fossil Record.
What Can we Learn From Fossils?
We Can Learn how Much or how Little Different Organisms Have Changed, as Life Developed on Earth.
What are ‘Evolutionary Trees’?
Evolutionary Trees are Diagrams that Show the Relationship Between Species, Over Evolutionary Time.
What does a New Branch in an Evolutionary Tree Represent?
A New Branch in an Evolutionary Tree Represents Where Speciation has Occurred (When a New Species has Evolved).
