2.4 billion years ago oxygen (O2) was introduced to the atmosphere and oceans for the first time in Earth's history due to the evolution and spread of photosynthesizing organisms! But although life eventually adapted to use this oxygen for their benefit (including humans and all other animals), the life at the time, 2.4 billion years ago was not as tolerant of oxygen. In fact, this increase in oxygen led to potentially the largest mass extinction of all time! Hope you enjoy this video about the largest mass extinction with the tiniest of culprits ;)

0:00 Rise of Oxygen on Earth
3:08 LongTerm Benefit of Oxygen Rise
4:34 Snowball Earth Events
5:20 ShortTerm Consequences of Oxygen Rise
6:54 Was this the largest Mass Extinction?
8:47 Not even the culprits were safe
11:02 Slow recovery in ‘Boring Billion’
12:25 Was the ‘Boring Billion’ really boring?

References: Geomicrobiology: https://amzn.to/2WAloTR
Earth System History: https://amzn.to/3v1Iy0G
Overview of Earth's Oxygenation & its Effects on Life: Lyons et al., 2021: https://doi.org/10.1089/ast.2020.2418
O2 Overshoot during GOE: Bekker & Holland, 2012: https://doi.org/10.1016/J.EPSL.2011.1...
Rise of Atmospheric O2: Kump, 2008: https://doi.org/10.1038/nature06587
Evolution of Ocean Chemistry: Anbar & Knoll, 2002: https://doi.org/10.1126/SCIENCE.1069651
Canfield et al., 2020: https://doi.org/10.1016/j.earscirev.2...
Yang et al., 2017: https://doi.org/10.1016/j.precamres.2...
Diamond et al., 2021: http://dx.doi.org/10.1002/97811195074...
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KrissansenTotton et al., 2015: https://doi.org/10.2475/04.2015.01
Role of Anoxygenic Photosynthesis: Johnston et al., 2009: https://doi.org/10.1073/pnas.0909248106

GEO GIRL Website: https://www.geogirlscience.com/ (visit my website to see all my courses, shop merch, learn more about me, & donate to support the channel if you'd like!)

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Nontextbook books I recommend:
Oxygen by D. Canfield: https://amzn.to/3gffbCL
Brief history of Earth by A. Knoll: https://amzn.to/3w3hC1I
Life on young planet by A. Knoll: https://amzn.to/2RBMpny
Some assembly required by N. Shubin: https://amzn.to/3w1Ezm2
Your inner fish by N. Shubin: https://amzn.to/3cpw3Wb
Oxygen by N. Lane: https://amzn.to/3z4FgwZ
Alien Oceans by K. Hand: https://amzn.to/3clMx1l
Life's Engines: https://amzn.to/3w1Nhke

Tools I use as a geologist/teacher/student:
Geology field notebook: https://amzn.to/3lb6dJf
Geology rock hammer: https://amzn.to/3DZw8MA
Geological compass: https://amzn.to/3hfbdLu
Geological hand lens: https://amzn.to/3jXysM5
Camera: https://amzn.to/3l6fGRT
Carbonneutral pencil bag: https://shrsl.com/3cvjv
Carbonneutral backpack: https://shrsl.com/3cvkc

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