2.5 The Origin and Development of Life on Earth Flashcards
What is the study of fossils known as?
Palaeontology
What are fossils?
The preserved remains of living things
What are 5 types of fossil you need to be able to identify?
- ammonites
- corals
- plants
- trace fossils
- trilobites
What are the parts of trilobites?
- cephalon (head)
- thorax (body)
- pygidium (tail)
What is a fossil track?
A trail on the seabed where a marine creature (e.g. ammonite) has been rolled along
What environment were trilobites formed?
Marine
What environment were corals formed?
Shallow marine
What environment were ammonites formed?
Warm shallow marine
What environment were plant fossils formed?
Cold forests (mangrove swamp-like conditions)
What is the main theory about how living things developed?
Living things developed from molecules that replicate themselves
What are the two possible origins for molecules that replicate themselves?
- they were produced by the conditions on earth at the time
* they came from somewhere else, such as another planet
What is deoxyribonucleic acid (DNA)?
A molecule that encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses
What is ribonucleic acid (RNA)?
A molecule that is involved in coding and expression of genes
What is one of the best examples of exceptional preservation?
The Burgess Shale fauna
Where did life probably originate from?
The oceans or hydrothermal pools
How long ago did life probably originate?
3500 Ma
How can the diversity in the evolution of life be identified?
From the fossil record
How was Burgess Shale formed?
Mudstones and shales laid down on floor of shallow sea
How is the Burgess Shale different?
Some soft bodies were also preserved as fossils
How were some soft bodies preserved in the Burgess Shale?
Conditions for fossilisation were perfect - shallow sea
What did the development of predators in the Cambrian era cause?
The rapid evolution of defensive features e.g. armour, mineralised bodies and shells
What group did over half of the fossils in the Burgess Shale come from?
Arthropods
What were the most abundant arthropods?
Trilobites
What animal in a fossil shows the evolutionary links between different groups of animals or plants?
Archaeopteryx
How was the rock that archaeopteryx fossils are found in formed?
- limestone forming in marine conditions, with fossil sponges and animals creating reefs
- shallow water behind formed lagoon and water evaporated, and CaCO3 precipitated out as limy mud
- limestone separates into thin plates (used as building stone)
What species does the archaeopteryx link?
Reptiles and birds
How does the archaeopteryx link reptiles and birds?
It has wings with feathers, but a reptilian head with no obvious beak
What are the fossils of our closest biological relatives?
Hominids
How long ago was the hominid ‘Lucy’ estimated to lived?
3.2 million years ago
What is an Auatralopithecus afarensis?
A human-like creature
Which part of the body provides some of the best evidence for bipedal movement?
The femur (or thigh bone)
What is biostratigraphy?
The branch of dating rocks that assigns relative ages of rock units by using the fossils contained within them
What is correlation in biostratigraphy?
Demonstrating that a particular bed in one geological section represents the same period of time as another bed at some other section
Why are fossils useful when dating rocks?
Sediments the same age can look completely different due to local variations in the sedimentary environment
What does the oil industry use biostratigraphy for?
To correlate reservoir and cap rocks
What are Forams?
A type of microfossil
Where are Foraminifera found?
In all marine environment
What does it mean if a creature is planktonic?
They float around in the seawater
What does it mean if a creature is benthonic?
They live on the seabed
Is the fossil record complete?
No
