Locations
The Apex Chert was found in this part of the world.
What is Western Australia?
This is the approximate age of the Apex Chert evidence.
What is 3.465 billion years old?
This scientist identified microscopic filament-shaped structures in the Apex Chert as fossilized bacteria.
Who is Schopf?
The Pilbara structures are described as having this type of shape that resembles microorganisms.
What are filaments?
The Nuvvuagittuq Belt is located in this country.
What is Canada?
Schopf believed the organisms preserved in the Apex Chert lived in this type of environment.
What is a shallow marine environment?
The Pilbara hydrothermal filaments date back approximately this many billion years.
What is 3.2 billion years?
Schopf believed the Apex Chert organisms were similar in morphology to these modern organisms.
What are cyanobacteria?
One characteristic of the Pilbara filaments is that they have extremely ______ dimensions.
What are uniform dimensions?
These thread-like structures in the Nuvvuagittuq Belt were compared to structures made by modern bacteria near deep-sea vents.
What are fossil-like thread structures?
The Pilbara filaments were found in rocks preserved in this type of ancient environment.
What is an ancient seafloor/hydrothermal environment?
The Nuvvuagittuq Belt evidence may date to a range between these two ages.
What are 3.7–4.2 billion years ago?
Brasier argued that the Apex structures originated from these rather than fossilized microbes.
What are hydrothermally altered minerals?
The Pilbara structures resemble microbial mats found near these modern environments.
What are deep-sea vents?
This type of carbon was found in the Nuvvuagittuq evidence and can be associated with living organisms.
What is isotopically light carbon?
The Nuvvuagittuq Belt is located in this Canadian province and contains evidence suggesting the rocks formed on an ancient ocean floor.
What is Quebec?
Put these in order from oldest to youngest: Apex Chert, Pilbara filaments, Nuvvuagittuq Belt.
What is Nuvvuagittuq → Apex Chert → Pilbara?
According to Brasier, the structures were randomly distributed rather than appearing in the layers or groups expected from microbes.
What is one of Brasier's arguments against their biological origin?
Unlike mineral growths, the Pilbara structures lack this feature.
What is branching?
These minerals were found alongside the structures and were interpreted as supporting evidence for microbial activity.
What are carbonate minerals?
Both the Pilbara and Nuvvuagittuq evidence are associated with this type of environment, which is important because it could provide conditions for early microbial life.
What are hydrothermal vents/systems?
Of the three examples, this evidence could represent the earliest life because it may be as old as 4.2 billion years.
What is the Nuvvuagittuq Belt?
: Brasier argued that all of the shapes found in the Apex Chert could be produced without life.
What is abiotically?
This is the main argument against interpreting the Pilbara filaments as fossils.
What is that hydrothermal systems can naturally produce complex abiotic pseudofossils?
Give one reason scientists have questioned whether the Nuvvuagittuq structures are truly ancient fossils.
What is that the rocks have been metamorphosed, making it difficult to determine how they originally formed?
or: What is that microbes could have entered through cracks after the rocks formed?