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Sun 31 Mar 2019 09:37:56 AM EDT Slept from one to nine. Woke briefly around five. High of thirty-six today, breezy, scattered flurries. A quarter-inch of snow fell last night! That goose is back this year, nesting on top of the carports. Goals: - Work on some Go stuff (picture brightness, qw?) Done. - Run offsite backup Done. Love the stackoverflow 90's CSS theme. https://meta.stackoverflow.com/questions/382111/announcing-the-stack-overflow-time-machine Watched The Girl With All the Gifts. Good. "Do you want a cat?" "I already had one." Nice Greek myths tie-ins. "Where did you learn that?" "I watched you." Some excellent performances, particularly from Glenn Close and Sennia Nanua. ssh://paulgorman.org/~/repo/qw Ten-minute walk. https://www.newyorker.com/magazine/2019/04/08/the-day-the-dinosaurs-died > The asteroid struck a shallow sea where the Yucatán peninsula is today. In that moment, the Cretaceous period ended and the Paleogene period began. > Within two minutes of slamming into Earth, the asteroid, which was at least six miles wide, had gouged a crater about eighteen miles deep and lofted twenty-five trillion metric tons of debris into the atmosphere. Picture the splash of a pebble falling into pond water, but on a planetary scale. When Earth’s crust rebounded, a peak higher than Mt. Everest briefly rose up. The energy released was more than that of a billion Hiroshima bombs, but the blast looked nothing like a nuclear explosion, with its signature mushroom cloud. Instead, the initial blowout formed a “rooster tail,” a gigantic jet of molten material, which exited the atmosphere, some of it fanning out over North America. Much of the material was several times hotter than the surface of the sun, and it set fire to everything within a thousand miles. In addition, an inverted cone of liquefied, superheated rock rose, spread outward as countless red-hot blobs of glass, called tektites, and blanketed the Western Hemisphere. > Some of the ejecta escaped Earth’s gravitational pull and went into irregular orbits around the sun. Over millions of years, bits of it found their way to other planets and moons in the solar system. Mars was eventually strewn with the debris—just as pieces of Mars, knocked aloft by ancient asteroid impacts, have been found on Earth. A 2013 study in the journal Astrobiology estimated that tens of thousands of pounds of impact rubble may have landed on Titan, a moon of Saturn, and on Europa and Callisto, which orbit Jupiter—three satellites that scientists believe may have promising habitats for life. Mathematical models indicate that at least some of this vagabond debris still harbored living microbes. The asteroid may have sown life throughout the solar system, even as it ravaged life on Earth. > Most paleontologists rejected the idea that a sudden, random encounter with space junk had drastically altered the evolution of life on Earth. But as the years passed the evidence mounted, until, in a 1991 paper, the smoking gun was announced: the discovery of an impact crater buried under thousands of feet of sediment in the Yucatán peninsula, of exactly the right age, and of the right size and geochemistry, to have caused a worldwide cataclysm. The crater and the asteroid were named Chicxulub, after a small Mayan town near the epicenter. > One of the authors of the 1991 paper, David Kring, was so frightened by what he learned of the impact’s destructive nature that he became a leading voice in calling for a system to identify and neutralize threatening asteroids. “There’s no uncertainty to this statement: the Earth will be hit by a Chicxulub-size asteroid again, unless we deflect it,” he told me. “Even a three-hundred-metre rock would end world agriculture.” > Four years earlier, in Hell Creek, he and a field assistant, Robert Feeney, found an odd, lumpy growth of fossilized bone that turned out to be two fused vertebrae from the tail of a hadrosaur, a duck-billed dinosaur from the Cretaceous period. DePalma thought that the bone might have grown around a foreign object and encased it. He took it to Lawrence Memorial Hospital, in Kansas, where a CT technician scanned it for free in the middle of the night, when the machine was idle. Inside the nodule was a broken tyrannosaur tooth; the hadrosaur had been bitten by a tyrannosaur and escaped. > The discovery helped refute an old hypothesis, revived by the formidable paleontologist Jack Horner, that T. rex was solely a scavenger. > “Here’s a piece of wood with bark-beetle traces,” he said. Plant fossils from the first several million years after the impact show almost no signs of such damage; the insects were mostly gone. The asteroid had likely struck in the fall, DePalma speculated. He had reached this conclusion by comparing the juvenile paddlefish and sturgeon he’d found with the species’ known growth rates and hatching seasons; he’d also found the seeds of conifers, figs, and certain flowers. “When we analyze the pollen and diatomaceous particles, that will narrow it down,” he said. > He planned to remove the entire burrow intact, in a block, and run it through a CT scanner back home, to see what it contained. “Any Cretaceous mammal burrow is incredibly rare,” he said. “But this one is impossible—it’s dug right through the KT boundary.” Perhaps, he said, the mammal survived the impact and the flood, burrowed into the mud to escape the freezing darkness, then died. “It may have been born in the Cretaceous and died in the Paleocene,” he said. “And to think—sixty-six million years later, a stinky monkey is digging it up, trying to figure out what happened.” He added, “If it’s a new species, I’ll name it after you.” > At the bottom of the deposit, in a mixture of heavy gravel and tektites, DePalma identified the broken teeth and bones, including hatchling remains, of almost every dinosaur group known from Hell Creek, as well as pterosaur remains, which had previously been found only in layers far below the KT boundary. He found, intact, an unhatched egg containing an embryo—a fossil of immense research value. The egg and the other remains suggested that dinosaurs and major reptiles were probably not staggering into extinction on that fateful day. In one fell swoop, DePalma may have solved the three-metre problem and filled in the gap in the fossil record. Servings: grains 6/6, fruit 3/4, vegetables 2/4, dairy 6/2, meat 5/3, nuts 0/0.5 Brunch: eggs with tomato, cucumber, mandarin, banana, coffee Afternoon snack: apple Dinner: pizza 124/79

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