Readers following the cat evolution posts might wonder why we’ve stayed in the Precambrian for so long.
There are three main reasons for that.
Reason #1: Where’d those cats come from?
If felines show up on your doorstep a few minutes before noon and they’re not yours, you’ll need to trace those adorable little paw prints back through the morning to see where they came from.
Paleontology works much the same way, only with fossils and a host of lab studies in addition to the tracks.
On this “clock” version of the geological time scale, our doorstep is the Phanerozoic (“recent life,” though it goes back some 540 million years to the Cambrian “explosion” of life) — the blue segment.
The Precambrian morning is everything else — a train of multi-billion-year-old individual eons:
It’s hard enough to grasp how long geological periods are (roughly 80 million years for the dinosaur-packed Cretaceous), or even epochs like the Holocene, just 12,000 years old, in which we’re living now.
The Holocene began when the last ice age ended, and doesn’t that seem like an unfathomably long time ago!
How can we wrap our minds around three Precambrian eons?
More to the point, why should we try?
Because of —
Reason #2: It’s fun!
Well, it is for me — like exploring a new planet and rediscovering your own at the same time — and I’m trying my best to pass that fun along to you.
Precambrian Earth was a happening place!
Supercontinents formed, broke apart, and re-formed; oceans and shallow seas appeared and disappeared, changing color along the way depending on their iron, sulfur, and (eventually) oxygen content; enormous eruptions occurred (this Sunday Morning Volcano series is about some of them); mountain chains rose, weathered down into plains, and sometimes rose anew; global and local climates rang the changes as Earth alternately sweltered or froze.
And life soldiered on through it all, evolving into animals that left their first unambiguous fossils at the dawn of the Phanerozoic roughly 540 million years ago.
That’s amazing! But how did it all happen? Would animals have appeared without all that geological drama?
I don’t know. Even the experts still debate such questions.
But one thing is for sure: it’s interesting.
I’d like to talk about that geology a bit, particularly supercontinents and the intense volcanism associated with them, while carrying on with cat evolution in the main series.
This is both for background and because it’s an opportunity to look at massive eruptions called large igneous provinces (LIPs), which is always fun (since these 100,000-plus km3 events are now long ago and far away).
Reason 3: LIPs affect evolution in major ways
Our own eon has been exciting, and here’s something you might not know about it: the Phanerozoic is divided into periods that end in life crises because these stand out so clearly in the fossil record (which is pretty good for the last 540 million years).
For instance, in North America, the record shows that nonavian dinosaurs disappeared around 66 million years ago. So did many marsupial mammals, but placental mammals — the group that cats belong to — were also around in the Cretaceous and they replaced the marsupials in the next period, called the Paleogene. (Prothero)
This crisis occurred around the world and changed whole ecosystems (McGhee et al.), so it made sense to set a timeline boundary there, between the Cretaceous and the Paleogene, regardless of what the cause(s) of that mass extinction might have been.
And so it goes throughout our Phanerozoic.
Perhaps you have heard of other crises, like the end-Permian extinction.
Yes, the Permian was a period; so was the Triassic, which followed it and which also ended in a major mass extinction.
Life, extinction, and geological periods all fit together since Cambrian times. Unfortunately, geologists can’t be that precise with their Precambrian time scale yet.
There just aren’t that many fossils or clear-cut biomarkers from back then to work with.
Too, Precambrian rocks are usually so altered that it’s difficult for geoscientists to interpret them in ways that everyone can agree on.
Some researchers, Prokoph et al. in particular, note that large igneous provinces (LIPs) in the Phanerozoic appear to be connected with life crises and possibly could be used to divide up the Precambrian into more manageable periods of geologic time.
Here’s a video that shows what they are talking about, using the worst mass extinction of the Phanerozoic thus far as an example (part 2 gets a separate post:
Relax. These things happen on average every 30 million years, and the last one, in the Pacific Northwest, occurred roughly 17 million years ago.
We’ve still got some time before the next one. Probably.
I don’t know how widespread support is for the time-scale suggestion from Prokoph et al., but they do present a good argument for it.
Anyway, the debate about geologic time is for scientists. On a lay level, this LIP approach is a good way for those of us interested in cat evolution to experience some Precambrian excitement, as well as to better understand the setting in which lineages evolved that somehow led to the very first animals and plants.
In the cat evolution series, we’re currently working through cat-related evolutionary milestones associated with the Proterozoic’s surprisingly eventful “Boring Billion” years and the subsequent two major “snowball” phases.
At that point, according to some hypotheses, Earth may have been trying to return to a form of its original “stagnant-lid” tectonics with the supercontinent Columbia. (Mukherjee et al.; Palin and Santosh)
Unlike other rocky planets like Mars and Venus, Earth instead transitioned into the plate tectonics that still operates today.
This process involved LIPs and a few traces of those remain. Next time, let’s start with a look at those.
Featured image: Alex Kapov/Shutterstock
Arndt, N. T., and Nisbet, E. G. 2012. Processes on the young Earth and the habitats of early life. Annual Review of Earth and Planetary Sciences, 40: 521-549.
Carlson, R. W.; Garçon, M.; O’neil, J.; Reimink, J.; and Rizo, H. 2019. The nature of Earth’s first crust. Chemical Geology, 530: 119321.
Catling, D. C., and Zahnle, K. J. 2020. The Archean atmosphere. Science Advances, 6(9): eaax1420. https://www.science.org/doi/10.1126/sciadv.aax1420
Corsetti, F. A.; Olcott, A. N.; and Bakermans, C. 2006. The biotic response to Neoproterozoic snowball Earth. Palaeogeography, Palaeoclimatology, Palaeoecology, 232(2-4): 114-130.
El Albani, A.; Bengtson, S.; Canfield, D. E.; Riboulleau, A.; and others. 2014. The 2.1 Ga old Francevillian biota: biogenicity, taphonomy and biodiversity. PLoS One, 9(6): e99438.
Gradstein, F. M.; Ogg, J. G.; and Hilgen, F. G. 2012. On the geologic time scale. Newsletters on Stratigraphy. 45(2):171-188.
Hohmann-Marriott, M. F., and Blankenship, R. E. 2011. Evolution of photosynthesis. Annual Review of Plant Biology, 62: 515-548.
Hsia, C. C.; Schmitz, A.; Lambertz, M.; Perry, S. F.; and Maina, J. N. 2013. Evolution of air breathing: oxygen homeostasis and the transitions from water to land and sky. Comprehensive Physiology, 3(2): 849.
Javaux, E. J., and Lepot, K. 2018. The Paleoproterozoic fossil record: implications for the evolution of the biosphere during Earth’s middle-age. Earth-Science Reviews, 176: 68-86.
Kharecha, P.; Kasting, J.; and Siefert, J. 2005. A coupled atmosphere–ecosystem model of the early Archean Earth. Geobiology, 3(2): 53-76.
Kitadai, N., and Maruyama, S. 2018. Origins of building blocks of life: A review. Geoscience Frontiers, 9(4): 1117-1153.
Knoll, A. H. 2014. Paleobiological perspectives on early eukaryotic evolution. Cold Spring Harbor Perspectives in Biology, 6(1): a016121.
Koonin, E. V. 2010. The origin and early evolution of eukaryotes in the light of phylogenomics. Genome Biology, 11(5): 1-12.
Lane, N.; Allen, J. F.; and Martin, W. 2010. How did LUCA make a living? Chemiosmosis in the origin of life. BioEssays, 32(4): 271-280.
Lyle, M.; Barron, J.; Bralower, T. J.; Huber, M.; and others. 2008. Pacific Ocean and Cenozoic evolution of climate. Reviews of Geophysics. 46: RG2002.
Morton, M. C. 2017. When and how did plate tectonics begin on Earth? https://www.earthmagazine.org/article/when-and-how-did-plate-tectonics-begin-earth/
Mukherjee, I.; Large, R. R.; Corkrey, R.; and Danyushevsky, L. V. 2018. The Boring Billion, a slingshot for complex life on Earth. Scientific Reports, 8(1): 1-7.
NASA. 2020b. Life in our Solar System? Meet the neighbors. https://exoplanets.nasa.gov/news/1665/life-in-our-solar-system-meet-the-neighbors/ Last accessed July 12, 2021.
___. 2021. NASA selects 2 missions to study “lost habitable” world of Venus. https://www.nasa.gov/press-release/nasa-selects-2-missions-to-study-lost-habitable-world-of-venus Last accessed July 12, 2021.
___. 2021a. Then there were 3: NASA to collaborate on ESA’s new Venus mission. https://www.nasa.gov/feature/then-there-were-3-nasa-to-collaborate-on-esa-s-new-venus-mission Last accessed July 12, 2021.
___. 2021b. Venus overview. https://solarsystem.nasa.gov/planets/venus/overview/ Last accessed July 12, 2021.
___. 2021c. The searchers: How will NASA look for signs of life beyond Earth? https://exoplanets.nasa.gov/news/1681/the-searchers-how-will-nasa-look-for-signs-of-life-beyond-earth/ Last accessed July 12, 2021.
__. 2021d. Life in the universe: What are the odds? https://exoplanets.nasa.gov/news/1675/life-in-the-universe-what-are-the-odds/ Last accessed July 12, 2021.
___. 2021f. What’s out there? The exoplanet sky so far? https://exoplanets.nasa.gov/news/1673/whats-out-there-the-exoplanet-sky-so-far/ Last accessed July 12, 2021.
___. 2021e. Mars 2020 Perseverance rover. https://mars.nasa.gov/mars-exploration/missions/mars2020/ Last accessed July 12, 2021.
___. n.d. Europa Clipper: Ingredients for life. https://europa.nasa.gov/why-europa/ingr.edients-for-life/ Last accessed July 12, 2021
Oppenheimer, C. 2011. Eruptions That Shook the World. Cambridge: Cambridge University Press. Retrieved from https://play.google.com/store/books/details?id=qW1UNwhuhnUC
Palin, R. M., and Santosh, M. 2020. Plate tectonics: What, where, why, and when?. Gondwana Research. (PDF)
Prokoph, A.; Ernst, R. E.; and Buchan, K. L. 2004. Time-series analysis of large igneous provinces: 3500 Ma to present. The Journal of Geology, 112(1): 1-22.
Prothero, D. R. 2006. After the Dinosaurs: The Age of Mammals. Bloomington and Indianapolis: Indiana University Press. Retrieved from https://play.google.com/store/books/details?id=Qh82IW-HHWAC
Reddy, S. M., and Evans, D. A. D. 2009. Palaeoproterozoic supercontinents and global evolution: correlations from core to atmosphere. Geological Society, London, Special Publications, 323(1), 1-26.
Rogers, J. J., and Santosh, M. 2004. Continents and supercontinents. Oxford University Press. (PDF)
Schopf, J. W. 1994. Disparate rates, differing fates: tempo and mode of evolution changed from the Precambrian to the Phanerozoic. Proceedings of the National Academy of Sciences, 91(15), 6735-6742.
Simpson, G. G. 1944. Tempo and Mode in Evolution. New York: Columbia University Press.
Sleep, N. H. 2010. The Hadean-Archaean environment. Cold Spring Harbor Perspectives in Biology, 2(6): a002527. http://m.cshperspectives.cshlp.org/content/2/6/a002527.long
Sleep, N. H., Bird, D. K., & Pope, E. C. (2011). Serpentinite and the dawn of life. Philosophical Transactions of the Royal Society B: Biological Sciences, 366(1580), 2857-2869. https://royalsocietypublishing.org/doi/full/10.1098/rstb.2011.0129
Strahler, A. N. 1970. Introduction to Physical Geology, second edition. John Wiley & Sons.
Taylor, S. R., and McLennan, S. M. 1995. The geochemical evolution of the continental crust. Reviews of Geophysics, 33(2): 241-265.
Walker, S. I. 2017. Origins of life: a problem for physics, a key issues review. Reports on Progress in Physics, 80(9): 092601.
Walker, S. I.; Packard, N.; and Cody, G. D. 2017. Re-conceptualizing the origins of life. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences,375: 20160337.
Waltham, D. 2015. Milankovitch period uncertainties and their impact on cyclostratigraphy. Journal of Sedimentary Research, 85(8): 990-998.
Wessner, D. R. 2010. The origins of viruses. Nature Education, 3(9), 37. https://www.nature.com/scitable/topicpage/the-origins-of-viruses-14398218/
Zahnle, K.; Schaefer, L.; and Fegley, B. 2010. Earth’s earliest atmospheres. Cold Spring Harbor Perspectives in Biology, 2(10): a004895. http://m.cshperspectives.cshlp.org/content/2/10/a004895.long