Otherlands: Adventures in Earth’s Extinct Ecosystems – Thomas Halliday

Overview: In Otherlands, Thomas Halliday imagines and brings to life organisms and ecosystems from the Earth’s deep past - what a time traveller would see, hear and feel if they made a visit to a particular moment in Earth’s history - based on fossil evidence and comparisons with modern-day life.

Thoughts: I thoroughly enjoyed reading Otherlands - if PBS Eons had announced several years ago they were releasing a book, this is exactly the book I would have hoped for. It could have been much improved by the presence of one or two illustrations per chapter, rather than one illustration every chapter or two. Despite this, Otherlands is an excellent book - would recommend it to anyone interested in the history of life on earth.

(The notes below are not a summary of the book, but rather raw notes - whatever I thought, at the time, might be worth remembering. I read this as an e-book, so page numbers are as they appeared in the app I used, Libby.)

Halliday, Thomas. 2022. Otherlands: Adventures in Earth’s Extinct Ecosystems. Allen Lane.

1. Thaw: Northern Plain, Alaska, USA - Pleistocene

• 31: “The possible survival conditions for any given species [are] its ‘fundamental niche’. When interactions with other organisms limit that niche, we call the reality of a species distribution its ‘realized niche’. No matter how wide the fundamental niche is, if the environment changes, and passes outwith the limits of that niche, or, if the realized niche slips to a size of zero, that species has gone extinct.”
• 33: “The steppe continues to exist because of [its continuity across a wide geographic area]. Ice Age weather patterns are volatile, with conditions often wildly different from year to year. If you were to drive tent pegs into the loose ground and set up camp for years in one place, the populations would seem to go through extreme cycles of boom and bust, with the weather and plant life one year favouring horses, then bison, then mammoths, and so on. Because the mammoth steppe is contiguous, species can move to follow their ideal climates, and stay within the bounds of their niches. In a wildly variable environment, mobility is crucial to long-term survival. Somewhere on the continent, there will always be refuge.”

2. Origins: Kanapoi, Kenya - Pliocene

• 48: “So at home are swifts in the sky that they can remain airborne for ten months at a time, feeding, mating, and, by resting only half of their brains at a time, even sleeping on the wing.” !!
• 54: Plants that practice C₄ photosynthesis are especially favoured by arid conditions (C₄ photosynthesis involves concentrating nutrients around plants’ RuBisCo and away from its stomata, which takes energy to do but leads to more energy captured per unit of water lost during photosynthesis), conditions which have been common over the past several million years. “Since C₄ plants have become more prevalent, and because they are poorer sources of nutrition, herbivores have had to adapt their feeding behaviour to the changing flora.”

3. Deluge: Gargano, Italy - Miocene

• 67: “for every kilometre a wind falls, its temperature increases by about 10°C. This is a cool period in Earth’s history, but even so, on a hot day, maximum summer air temperatures 4 kilometres down at the base of the plain [in the Mediterranean basin] could reach a hellish 80°C - some 25°C hotter than the hottest temperature ever recorded in modern times in Death Valley, California” !!
• 70: “New Zealand’s pouākai, that Pleistocene hunter of moa with a 3-metre wingspan, an eagle so terrifying as to persist in Māori folklore long after its extinction.” j: I know that extinct species are depicted in petroglyphs in places. I wonder where else extinct species have left traces in oral histories.
• 74: Island dwarfism/gigantism - the two parts of “the general rule that island animals tend towards a medium size”: “over time, in the absence of ordinary predators, many large animals, whose size would otherwise offer protection against predation - such as deer, and, and other islands, hippopotamuses and elephants - become smaller as food is scarcer. Small animals, which cannot store energy or water as easily, become larger, aiding the survival of the population through periods of scarce resources.”
• 80f: “Antlers grow through a mechanism that is very similar to cancer, but because deer can keep that growth in check, they are extremely resilient to cancers, with 20 per cent the rate of cancer in other wild mammals.” !

4. Homeland: Tinguiririca, Chile - Oligocene

5. Cycles: Seymour Island, Antarctica - Eocene

• 119: “Unlike at Gargano, when the island rule benefited a medium size… In the polar regions, the extremes are favoured. There are two ways to survive the cold. One is to hibernate, as the… small creatures do, to modify internal physiological processes, such that a winter can be endured. The other is to increase in size, reducing surface area relative volume, and keeping warm through bulk. A medium-sized animal cannot do either, and so, in the Eocene of Seymour island, there is nothing between the sizes of rabbit and sheep.”

6. Rebirth: Hell Creek, Montana, USA - Paleocene

• 128: As rain falls on vegetation, “the water that runs off and soaks into the soil takes with it some of [the] water-resistant wax [produced by all leaves]. Each type of wax has a chemical composition characteristic of the leaves from which it drips, and will give the soil a signature of the plants that once shaded it. Flowering plants produce more wax than cone-bearing plants, and both have wax made of longer molecules than the wax of mosses. In more arid environments, the wax molecules are longer, which prevents the loss of water into the dry air. That chemistry is retained even as the soil hardens and mineralizes into rock and, to a point, can reveal which plants were once present. Long after death, incorporated into the bedrock, their combined and dappled chemical shadows will remain.”
• 132: There exists a gene that codes for a protein that can digest chitin, of which insect exoskeletons are composed. When animals stop eating insects, random mutations begin to degrade these genes. “The remnants of these genes can be found in humans, in horses, in dogs and cats, a vague genetic memory of an insectivorous past, and one in which, intriguingly, the losses appear to have happened independently of one another.”
• 134: The crocodilians fared very poorly during the KPG extinction event relative to other reptilian families. “Far from all being semi-aquatic ambush predators, Cretaceous crocodiles included the agile and cat-like Pakasuchus of Tanzania; the fully marine thalattosuchian family with their flippers and shark-like tails; the pug-nosed Simosuchus, a clove-toothed burrowing herbivore from Madagascar, only the size of an iguana, that despite the advantages of that lifestyle, still didn’t make it.”

7. Signals: Yixian, Liaoning, China - Cretaceous

• 153: “Black and yellow are high-contrast and stand out against the green of the leaves even in creatures with no colour vision, deterring even individuals unfamiliar with the danger. There is a continuity here, with the same signals that caused a dinosaur to think twice about messing with a wasp as those that cause a modern-day picnicker to do a double-take. The warning colouration of insects uses a shared visual language that has persisted for more than 100 million years.”
• 159: (during a discussion of dinosaurs in which males would guard nests of eggs laid by multiple females) “Any female that can produce the complex pigments protoporphyrin and bilirubin to the extent that she lays strongly blue-green eggs must be a healthy, successful feeder, and the father can expect that any offspring hatching out of those eggs are likely also to be successful. Oviraptorosaurs are caring parents, but brighter eggs in living dinosaurs [i.e., modern-day birds] elicit a bigger caring response from the father; one of the few examples of sexual selection occurring after mating has already taken place.”

8. Foundation: Swabia, Germany - Jurassic

• 169: “The cells that make up [glass sponges’] supportive tissue fuse together, channels opening in a way that allows the flow of the internal cell fluid, the cytoplasm, from cell to cell. In a very real sense, glass sponges come close to being a single celled organism, with the ‘syncytium’ leaving very little to distinguish the functioning of a glass sponge from that of a highly complex single cell. This interconnectivity means that a glass sponge can easily send electrical signals throughout its body, allowing it to respond quickly and effectively to stimuli and to change the rate at which water is filtered through its body – impressive for a creature that otherwise lacks a nervous system.”

9. Contingency: Madygen, Kyrgystan - Triassic

10. Seasons: Moradi, Niger - Permian

11. Fuel: Mazon Creek, Illinois, USA - Carboniferous

• 224-225: “The longest river in Antarctica, the Onyx, flows inland into Lake Vanda, a lake with three layers of water of different salt concentrations. The differences in salinity are enough to overcome extreme differences in temperature; the bottom layer of Lake Vanda is continually a balmy 23ºC, but the uppermost layer is close to freezing.”
• 228: Why was coal formed during the Carboniferous Period? One hypothesis that doesn’t have to do with the novelty of lignin: the Carboniferous was “the only time in earth’s history where the tropics have been both extensively wet and dominated by geographic basins.”

12. Collaboration: Rhynie, Scotland, UK - Devonian

13. Depths: Yaman-Kasy, Russia - Silurian

• 254: “As the superheated water [of subterranean vents] cools against its surroundings, it emits photons – thermal radiation. The light from vents is strong enough that, in the modern day, a species of bacterium is known to use it for photosynthesis, some 2.5 kilometres below the reaches of the sun.”

14. Transformation: Soom, South Africa - Ordovician

• 281: “When the world warms or cools, moving north or south can mean that habitable conditions are also found. In the Late Ordovician, the placement of almost all the world’s land south of the equator, centred on the south pole, makes this nearly impossible. The coast of Gondwana runs for tens of thousands of kilometres, but much of it is at about the same latitude.” j: cf. Guns Germs and Steel - will this effect mean the Americas and Africa will be somewhat insulated from extinctions as climate change intensifies?

15. Consumers: Chengjiang, Yunnan, China - Cambrian

16. Emergence: Ediacara Hills, Australia - Ediacaran