Dinosaurs and the Battle of Killers
An impact drove the dinosaurs extinct; or was it volcanoes?
For decades, the most common tale about dinosaur extinction has been the impact hypothesis: a meteorite finished them off. There’s the smoking-gun crater in the Yucatan, isn’t there? This theory gets treatment as “received knowledge” by the press. It’s simply assumed, as in PhysOrg‘s headline, “Asteroid that wiped out dinosaurs may have nearly knocked off mammals, too.” This article claims that early marsupials perished in the flames of the impact, somehow giving placental mammals their chance. Result: humans.
Dr. Steve Brusatte of the University of Edinburgh’s School of GeoSciences, an author on the report, said: “The classic tale is that dinosaurs died out and mammals, which had been waiting in the wings for over 100 million years, then finally had their chance. But our study shows that many mammals came perilously close to extinction. If a few lucky species didn’t make it through, then mammals may have gone the way of the dinosaurs and we wouldn’t be here.“
Not everyone has been convinced by the impact hypothesis (2/10/13). Another group, noticing the huge volcanic deposits in Indian known as the Deccan Traps, has fingered volcanoes as the agent of dinosaur demise. Those eruptions blanketed 123,000 cubic miles with lava. Supporters of the volcano hypothesis, championed for years by Princeton geologist Gerta Keller, also claim that dinosaurs were on the decline tens of thousands of years before the Chicxulub impact event.
Now, according to Princeton researchers, better dates from zircons have become available that put the extinction closer to the time the India volcanoes were erupting. “An incredible outpouring of lava 66 million years ago could have set off environmental changes that killed off the dinosaurs,” Becky Oskin writes for Live Science. The Princeton geologists do not deny the meteor strike, but assign it a finishing-off role to an extinction that was already underway. The most intense phase of the Deccan Traps eruptions was 66.29 million years ago, according to the newer zircon dating methods. It had started a million years before the K-T impact, according to PhysOrg, but then became more intense 250,000 years prior.
What’s not often stated by the meteorite theorists is that the extinction occurred 30,000 years after the impact. That’s not quite the instantaneous die-off pictured in the TV shows.
The volcano theorists have their troubles, too. The dates were calculated from selective zircons at particular layers. “We don’t know which of the flows correlates with the extinction,” geologist Blair Schoene said, despite the confident-sounding claims in the articles. “There’s a lot more work to be done.”
One person in the comments wondered why the huge lava flows that cover much of Oregon are not associated with an extinction event. The Princeton team, on the other hand, claims that no other extinction is associated with an impact. Maybe it was worms that did the dinosaurs in (10/24/06).
Evolutionary explanations for dinosaur extinction have evolved over the years from one consensus to another in a random walk. Impact craters are real, and lava flows are real, but the dates and associations with extinctions are flimsy. It’s all moot, anyway, now that soft tissue from multiple dinosaurs has been discovered throughout the past decade. A few dinosaurs survived the Flood, but were finished off as pests by dragon slayers like St. George. That explains the selective extinction (why would butterflies survive but not dinosaurs?) as well as the survival of the soft tissue; it’s not millions of years old.