Fossils Flashcards
What is a fossil
preserved remains of once living organisms
what is an artefact
an object that has been changed/ modified by humans
Identify two conditions that favour fossilisation and describe why they are needed?
Fast burying
List 3 limitations with the fossile recorc
- Quick Bury
- Intact hard body parts
3.Absence of decay organisms - undisturbed for a long period of time
Types of fossils
Mold-> a hollow impression created from the sediments
Cast-> occurs when the mould fossil is filled with minerals and allowed to hardened
Mineral Fossils->
waterborne minerals fill the void spaces within the original material of the specimen
the original organic material of a specimen is replaced by minerals.
Index Fossils-> commonly found in a certain short time period, widely distributed useful for dating rocks in which they are found.
Describe the features of Index Fossils
Widespread-> found in a wide range of location
Found in large number->can be easily found
Recognisable-> is easily distinguishable and identifiable
Lived for a short period of time-> easily dated, can track the age of the fossil
Describe fossilisation
.The chance of fossilisation is relatively small
.When organism dies , decayed by microorganisms. Leaving traces of the organism
.Soft tissues are rarely preserved simultaneously, hard tissues are to more common to be fossilised.
Outline the condition ( Rapid burying) of fossilisation.
In order for fossils to form the process of fossilisation the decaying/ decomposition must be slower.
-> Drifting Sand
-> Mud depositied by rivers
-> Volcanic Ash
Organisms that die in water, not on land, are more likely to be buried quickly by sediments and are less likely to be destroyed by scavengers or by processes like erosion.
quicker buried by Sediment
Lower chance to be destroyed by scavenger or erosion
Lakes are more favourable as remains are less likely to be destroyed by mechanical processes.
Outline the condition (Soil quality) of fossilisation.
Wet, acidic soils contain oxygen within which dissolves the “ calcium/ minerals” of the bone thus no fossilisation occurs.
The more favourable soil trait would be basic/ alkaline as there is no present oxygen which dissolves the bomes thus fossilisation occurs.
Soils with no oxygen and in low temperature allows for further preservation of tissue
How to find fossils
The main way to find fossils is excavation
Describe Fossil reconstruction
.Fossils are not usually found full intact and must be reconstructed
. Reconstructions done by scientists are approximations
What is the fossil record and why is it not complete?
The evidence provided by fossils of the development of life.
. Limited amount of organisms fossilized
. not many fossils have beem found
Analyse the problems with the fossil record ,expand on why it’s not complete.
- Fossilisation is a rare occurence that requires specific conditions such as; quick burial, presence of hard body parts, left undisturbed , absence of decayed organisms.
- Must be discovered thus may be already destroyed
- Dating fossils can be difficult
- Fossils are not often whole organisms thus fossil reconstruction must be done by scientists which may in turn also be in accurate.
What is the reason for the gaps and what conditions are needed for fossilisation to occur.
Describe two reasons why gaps in fossil record exist
