Courtney Case and the Dinosaur
Two new studies, published this week in Science, provide fresh clues to this unsolved mystery. They attempt to pin down the timing of the eruptions to uncover whether they played a significant role in the mass extinction. Broadly speaking, both studies find that volcanism was going strong when the die-off happened, and they offer various accounts about how it might have impacted life.
In fact, the studies disagree on crucial details — such as whether there was a big burst of lava right before the asteroid impact, or shortly after it. Scientists are trying to reconstruct events that unfolded over thousands of years, millions of years ago, said Will Clyde , a geologist at the University of New Hampshire who was not involved in the studies. The eruptions in question did not come out of a single volcano, like Mount St.
Helens in Washington. These kinds of eruptions occurred during four of the five mass extinctions in the last million years. The event that killed off the dinosaurs, on the other hand, is the only one linked to an asteroid impact. Eruptions probably do damage mainly by changing the climate. They release sulfur compounds that can cool the planet for years, or even centuries. They also release massive amounts of carbon dioxide, which causes global warming that lasts for many thousands of years.
And, as we are learning today, high concentrations of CO 2 can also lead to other problems, such as ocean acidification.
But were the events in India potent enough to help bring down the dinosaurs and their contemporaries? Part of the answer may lie in the resulting volcanic rocks. Known as the Deccan Traps, they cover an area the size of Texas in western India. For the new studies, both teams of researchers collected samples from these layers.
They wanted to figure out when the eruptions occurred, and whether the order of events suggested that the volcano had any part in causing the mass extinction. The two groups used different techniques, just as one detective might study analyze video from a security camera to place a suspect at a crime scene, while another might scour his or her phone records. They form in magma before it erupts, and they incorporate atoms of uranium as they grow. Because uranium is radioactive, some of it decays into lead. And because scientists know how long that takes, the amount of lead in a zircon gives an estimate of its age.
But other volcanoes in the region did, and the crystals wound up in layers of sediment and ash that collected between lava flows. The geologists estimated that the Deccan Traps began erupting about , years before the extinction, and continued for about , years afterward, perhaps slowing the recovery of life. The researchers also concluded that the layers of rock were produced in three huge pulses of volcanism, one of which occurred just before the fateful asteroid impact. That will require more research, he said.
But the other study , led by Courtney Sprain , a geoscientist at the University of Liverpool in England, does not. Also, the researchers studied a mineral in the basalt called plagioclase, not zircon. However, there are some important differences. That may be consistent with the idea that the asteroid impact stimulated more volcanic activity, which Sprain and her coauthors have previously suggested.
But the result complicates the question of whether the Deccan Traps played much of a role in killing off life. Both papers present new measurement and careful analyses, he said.
However, some researchers are skeptical that either investigation offers a compelling indictment of the Deccan Traps as a major cause of the mass extinction. Holtzinger heaved up the gun and let fly. He missed completely, and the kick knocked him flat on his back. He got up, looking paler than ever, and handed me back the gun, saying: "Uh—I think I'd better try something smaller.
When his shoulder stopped hurting, I tried him out on the smaller rifles. He took a fancy to my Winchester 70, chambered for the. This is an excellent all-round gun—perfect for the big cats and bears, but a little light for elephant and definitely light for dinosaur. I should never have given in, but I was in a hurry, and it might have taken months to have a new.
Do volcanoes or an asteroid deserve blame for dinosaur extinction?
Both sahibs had done a bit of shooting, so I didn't worry about their accuracy. Shooting dinosaur is not a matter of extreme accuracy, but of sound judgment and smooth coordination so you shan't catch twigs in the mechanism of your gun, or fall into holes, or climb a small tree that the dinosaur can pluck you out of, or blow your guide's head off.
People used to hunting mammals sometimes try to shoot a dinosaur in the brain.
That's the silliest thing you can do, because dinosaur haven't got any. To be exact, they have a little lump of tissue the size of a tennis ball on the front end of their spines, and how are you going to hit that when it's imbedded in a six-foot skull? The only safe rule with dinosaur is: always try for a heart shot. They have big hearts, over a hundred pounds in the largest species, and a couple of. The problem is to get the slugs through that mountain of meat around it. Well, we appeared at Prochaska's laboratory one rainy morning: James and Holtzinger, the Raja and I, our herder Beauregard Black, three helpers, a cook, and twelve jacks.
The transition chamber is a little cubbyhole the size of a small lift. My routine is for the men with the guns to go first in case a hungry theropod is standing near the machine when it arrives. So the two sahibs, the Raja, and I crowded into the chamber with our guns and packs. The operator squeezed in after us, closed the door, and fiddled with his dials. He set the thing for April twenty-fourth, eighty-five million b.
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The lights went out, leaving the chamber lit by a little battery-operated lamp. James and Holtzinger looked pretty green, but that may have been the lighting. The Raja and I had been through all this before, so the vibration and vertigo didn't bother us. The little spinning black hands of the dials slowed down and stopped. The operator looked at his ground-level gauge and turned the handwheel that raised the chamber so it shouldn't materialize underground.
Then he pressed another button, and the door slid open. No matter how often I do it, I get a frightful thrill out of stepping into a bygone era. The operator had raised the chamber a foot above the ground level, so I jumped down, my gun ready. The others came after. The chamber disappeared, and we looked around.
Do volcanoes or an asteroid deserve blame for dinosaur extinction?
There weren't any dinosaur in sight, nothing but lizards. In this period, the chamber materializes on top of a rocky rise, from which you can see in all directions as far as the haze will let you. To the west, you see the arm of the Kansas Sea that reaches across Missouri and the big swamp around the bayhead where the sauropods live. To the north is a low range that the Raja named the Janpur Hills, after the Indian kingdom his forebears once ruled.
To the east, the land slopes up to a plateau, good for ceratopsians, while to the south is flat country with more sauropod swamps and lots of ornithopod: duckbill and iguanodont. The finest thing about the Cretaceous is the climate: balmy like the South Sea Islands, but not so muggy as most Jurassic climates. It was spring, with dwarf magnolias in bloom all over. A thing about this landscape is that it combines a fairly high rainfall with an open type of vegetation cover.
That is, the grasses hadn't yet evolved to the point of forming solid carpets over all the open ground. So the ground is thick with laurel, sassafras, and other shrubs, with bare earth between. There are big thickets of palmettos and ferns. The trees round the hill are mostly cycads, standing singly and in copses. You'd call 'em palms. Down towards the Kansas Sea are more cycads and willows, while the uplands are covered with screw pine and ginkgoes.
Now, I'm no bloody poet—the Raja writes the stuff, not me—but I can appreciate a beautiful scene.
One of the helpers had come through the machine with two of the jacks and was pegging them out, and I was looking through the haze and sniffing the air, when a gun went off behind me — bang!