w/CS: The Ends of the World, Peter Brannon

The Ends of the World: Volcanic Apocalypses, Lethal Oceans, and our Quest to Understand Earth’s Past Mass Extinctions. Peter Brannon. 2017

April – June 2023

Summary of Periods and Mass Extinctions

Edicarian: 635-538. First appearance of wide-spread multi-cellular organisms in ocean: Soft-bodied microbial organisms forming mats and other structures, and free-floating filter feeders.
End-Edicarian extinction: ~448. 86% species went extinct.* Possibly due to advent of burrowing organisms that disrupted largely sessile ecosystem. Not an official mass extinction because of a very incomplete fossil record.
Cambrian: 538-485. Warm shallow seas flank margins of several continental remnants of the breakup of the supercontinent Pannotia. In ocean there is the advent of hard-bodied complex organisms, and subsequent explosion of diversity into all phyla known today. The land bare except for microbial crust; arthropods and mollusks begin to adapt to life on land towards the end of this period.
Ordovician: 485 – 433. High CO2 levels and continents inundated with vast shallow seas jammed with life: brachiopods; trilobites; cephalopods; eurypterids; grapholites; and jawless fish. Many isolated continents and islands, with continents at south pole and a global sea occupying most of the northern hemisphere. First spores of land plants (fungi and simple plants) at 467Ma, with their spread possibly releasing phosphorous into the ocean stimulating algal blooms and CO2 sequestration.
End-Ordovician extinction:~345 Ma. 75% species went extinct.* Major ice age, likely precipitated by biogenic CO2 depletion, followed by a whip-lash of warming.
Silurian: 443-419. Gondwanaland and island chains provide diversity of environments; in the ocean early fish diversify into jawed and bony fish. Terrestrial life expands in the Silurian-Devonian Terrestrial Revolution: vascular plants emerge from more primitive land plants, and three groups of arthropods (myriapods, arachnids and hexapods) became fully terrestrialized.
Devonian: 419-359. Gondwana supercontinent in the south, Siberia to the north, and Laurussia to the east. Free-sporing vascular plants form extensive forests (Archaeopteris); by the middle of the Devonian several groups have evolved leaves and true roots; by the end the first seed-bearing plants appear.
Late-Devonian extinction event: ~250 Ma. 96% species went extinct.* Two major extinction pulses, and many smaller pulses. One theory is that it is due to the release of nutrients by the punctuated spread of land plants as they developed vascular systems with leaves and roots, and seeds.
Carboniferous: 359-299. Age of amphibians — also first appearance of amniotes from which both reptiles and mammals came. Vast rainforests covered the land, and insects diversified. The latter part of the Carboniferous experienced glaciations, low sea level, and mountain building as the continents collided to form Pangaea. A minor marine and terrestrial extinction event, the Carboniferous rainforest collapse, occurred at the end of the period, caused by climate change
Permian: 299-251. On land: The Carboniferous rainforest collapse left behind vast regions of desert in the continental interior. Amniotes, which could better cope with the conditions, diversified into the synapsids (the ancestors of mammals which came to dominate the Permian) and the sauropsids (reptiles). . In the ocean fish diversify with placoderms dominating almost every known aquatic environment, alongside coeleocanths, with sharks and bony fishes on the sidelines.
End-Permian extinction: 251.9 Ma. 80% of species went extinct.* The Siberian Traps were created at 252 Ma and also interacted with the Tunguska sedimentary basin filled with carbonates, shale, coal and salt in layers up to 12 Km thick; it is the worlds largest coal basin. When the magma intersected the basin, it caught fire, detonated in multiple places, and released vast about of CO2 and methane, on top of the CO2 produced by the eruption contributing to global warming and ocean acidification and anoxia. Other chemicals produced by the incineration of the Tunguska basin contents may have destroyed the ozone layer.
Triassic: 252-201. Brannen argues for a long 5 – 10 million year recovery, but that is disputed. The ancestors of crodcodiles dominated the Triassic; ancestors of dinosaurs and first true mammals appear, but were not dominant. The global climate during the Triassic was mostly hot and dry. Pangea had deserts spanning much of its interior until ita began to gradually rift into Laurasia and Gondwana to the south. In line with this the climate shifted from hot and dry to more humid, with a massive rainfall event called the Carnian Pluvial Event that lasted a million years.
End Triassic Extinction: 200 Ma. 80% of species went extinct.* Volcanism from the rifting of Pangea produced flood basalt that covered more than 4 million square miles. The CO2 concentration doubled or tripled, raising the already warm temperatures by at least 3 ° C. The final extinction pulse was fast: on the order of 20,000 years.
Jurassic: 201.4 – 145. Gondwana begins to rift. Climate warm and humid.
Cretaceous: 145 – 66. Gondwana completes rifting and by the end of the period today’s continents are recognizable, but with shallow inland seas in North America and Africa and between Greenland and Norway.
End Cretaceous Extinction: xxx. 76% of species went extinct.* Most likely some combination of the eruption of the Siberian Traps and the Chixtulub impact lead to global warming and an extended period of darkness. Almost all large animals eliminated, including all dinosaurs excerpt ancestors of birds.

Percent of species that went extinct, for any one event, vary considerably among sources. These numbers are better read as an indicator of relative severity.

w/CS: The Tangled Tree: A Radical New History of Life, David Quammen

January – April 2023

The Tangled Tree: A Radical New History of Life, David Quammen, 2018. These are my chapter by chapter notes. Besides having very good reviews and being by a well-regarded author, this book got a (rare) very high rating from Reid Priedhorsky…

Read this with CS.

w/KC: Metaphors We Live By, Lakoff and Johnson, 1980

January 2023

The Book: Metaphors We Live By, George Lakoff and Mark Johnson, 1980

Prelude

Written in 1980, this book challenged what was then the conventional view of metaphor – in psychology, linguistics and philosophy – as a sort of minor, poetical flourish that had little to no role in the how people understand language. In sharp contrast, MWLB argued metaphor is central to not only the way humans understand language, but how they conceptualize and experience the world. The suggest that most metaphor is systematic, in that there are root metaphors which structure the way abstract topics are conceptualized. L&J distinguish among three types of metaphoriic systems: Structural (ARGUMENT IS WAR); Orientational (MORE IS UP); and Ontological (IDEAS ARE OBJECTS). They also not that metonymy, while it is referential rather than metaphorical, is systematic in the same way metaphor is.

w/CS: Alien Oceans: : The Search for Life in the Depths of Space, Kevin Peter Hand

25 October 2022 and on…

CS and I are reading Alien Oceans: The Search for Life in the Depths of Space, by Kevin Peter Hand. These are my chapter by chapter notes. We are now through chapter 7, and are enjoying it. It does not assume much science background, and thus spends a lot of time explaining things that we are familiar with (e.g. why water’s hydrogen bonds cause water ice to be lower density than liquid water). But it does a very good job of it, and those with background can skim; this would be a great book for a child or teen interested in science.

w/KC: Entangled Life: How Fungi Make Our Worlds, Change Our Minds & Shape Our Futures, Merlin Sheldrake

October – November 2022

These are chapter-by-chapter notes (with occasional quotes) on Entangled Life: How Fungi Make our Worlds, Change our Minds, and Shape our Futures, by M. Sheldrake. I’m reading this book with KC, a chapter or two at a time, and adding notes for each chapter as I go. Having now finished it, my one line review is that it has some fascinating stuff in it, but it is a lot more focused on cool stuff than on giving a detailed account of the science.

w/CS: Otherlands: A Journey Through Earth’s Extinct Worlds, Thomas Halliday- Introduction

Tuesday 15 March 2022

LATER: This is the best science book I have ever read; I have a 20+ page document of notes on both the content and the lyrical writing. I regret that I had not systematically started keeping notes in this blog at the point we were reading this.

This morning CS and I meet to begin our discussion of the book Otherlands, by Thomas Halliday. Halliday is a paleontologist and evolutionary biologist who investigates long-term patterns in the fossil record; he appears to be quite young, but has already won a raft of awards for his scientific work as well as one or two awards for his writing. A riffle through the book leaves me with high expectations. I note with approval that it has about fifty pages of notes, all pointing to various scholarly articles and books. The front matter includes an abbreviated chart of geolgical eras (mostly the Phanerozoic eon, presumably indicating the time-span covered in the book); I do like it that the book works backward in time rather than oldest first.