Lecture 21 Flashcards
(27 cards)
Which evolved first, bacteria and cyanobacteria, or the apex chert?
Bacteria and Cyanobacteria.
What are Cryptozoon?
The hiddn animal. Rocks that are older than Cambrian Rocks.
Where did we find Cryptozoon?
Schreiber Beach
What did we discover on Schreiber beach?
Observed column like structures and layering that demonstrates the structures ability to grow. Also observed fossilized bacteria like organisms.
What did the discoveries on Schreiber beach indicate?
That the first organisms were older than the phanerozoic, Proterozoic boundary (bacteria and cyanobacteria)
What did we discover in Shark Bay?
Column like formations existing in the zone between the lowest and highest tide. Support high water energy. Found more cryptozoon.
What are stromatolites?
Column like structures (cryptozoon is one of them). Successions of accumulations of limestone. Presents different shapes Distribution and morphology is affected by water depth and energy. Not an organism, but a structure that houses billions of prokaryotes.
Where were the oldest stromatolites?
Fig tree Formation in South Africa-3.2 billion years old.
What are the four components of stromatolites?
Growth surface, Undermat, Oxygen-depleted Zone, Stromatolite Mass
What is the Growth surface?
Thin layer (1mm) consisting of oxygen-producing photosynthetic cyanobacteria and aerobic bacteria.
What is the Undermat?
Thin bacterial layer (1mm), consisting of non-oxygen producing photosynthetic bacteria and anaerobic bacteria that can use oxygen.
What is the Oxygen-depleted zone?
Thick layer (around 1-2 centimetres). Only anaerobic bacteria (extremophiles).
What is the Stromatolite mass?
Includes most of stromatolite (a few centimeters to 1 metre). Non-living rock. Consists of calcium carbonate.
When did the stromatolites first start appearing?
In the Mesoarchean. Anything older is uncertain.
When did stromatolites reach global distribution?
In the Neoarchean (where there was water)
What major event in the history of life happened in the Paleoproterozoic?
Gun Flint Formation- stromatolites produced and expelled mass amounts of oxygen.
When did Earth’s atmosphere change from reducing to oxidizing?
In the Archean Proterozoic boundary.
What happened in the Phanerozoic?
Earliest gastropode organisms evolved. Fed on stromatolites. Reduced stromatolites back to patchy distribution.
What happened when the atmosphere changed from reducing to oxidizing?
Became toxic for Archean organisms. First mass extinction. Some prokaryotes lived due to symbiosis.
What are Eukaryotes?
Organisms with a true nucleus in cytoplasm mass. Larger than prokaryotes. Also have organelles.
What was the most important event in the emergence of life?
When prokaryotes turned into eukaryotes?
What was discovered about Eukaryotes that suggest how they formed?
Organelles have the same chemical composition as bacteria and cyanobacteria. Different prokaryotes clustered to form a eukaryote that was more adapted for the oxidizing atmosphere.
How did Eukaryotes begin the process of evolution?
Reproducing sexually. Producing distinct egg cells with mutations. Evolution itself evolved.
What is a Bangiomorpha?
Eukaryote with an Algae body. Consists of many cells. Demonstrate that algae developed multicellularity, Primitive and holds fast to sea floor. Erect body rose up to sunlight like other plants and trees in order to get energy.
