No Minister

The Fault In Our Stars

And now for something completely different.

Well perhaps not entirely different since it’s a story about mass death.

Last year I wrote an OP about the two great competing theories of what killed the dinosaurs 66 million years ago, and the scientific wars this had sparked through the 1980’s and right up to the present day: Dinosaur Wars and The Nine Foot Problem.

You can read the original piece but to recap: after decades of debate about what killed off the dinosaurs a theory was put forward in 1980 that the culprit was a giant asteroid that hit the earth near today’s Yucatán Peninsula in the Gulf of Mexico. The geological signature of the event is a notebook thick line of rock found around the world called the KT boundary. The crater was finally located in 1990 and is named after a nearby Mexican town, Chixalub, as is the asteroid and sometimes the entire event.

The strongest alternative theory was the Deccan Traps, giant fissure volcanoes in India that spewed out 720,000 cubic miles of lava over hundreds of thousands of years before and after the KT boundary was laid down. No scientist fought for that theory and dismissed the asteroid theory harder than the great Gerta Keller:

… she escaped death three more times: from hepatitis contracted during an Algerian coup she got caught up in, getting shot and badly wounded by an escaping bank robber in Australia, and getting food poisoning in India. She ended up in San Francisco, started studying anthropology and ended up with a PhD in geology at Princeton,

The main point of argument by Keller and others was that there’s no solid evidence of instant, mass death, but a steady decline in dinosaur and other lifeforms up to the KT boundary. 

Then, in just the last few years this long scientific war appeared to be drawing to an close with the discovery, in the Hell Creek formation in Montana, of a site that has preserved not only the day of the asteroid stike but even the hour. A graduate paleontologist, Robert DePalma, has found fossils of dinosaurs mixed in with tektites, small globs of molten rock blasted into the atmosphere by the asteroid that fell back to earth thousands of miles away.

Pretty darned convincing to me but then I’ve always been a fan of the Dinosaurs-Get-Nuked theory. And now there may be an equally solid case on favour of the Chixalub asteroid from a slightly different field of science.

Meet Pincelli Hull. Aside from having an awesome name, she has not quite got the same backstory as Keller, although her life has shown the same free spiritedness.

My name is Pincelli Hull. I’m a Biologist. And I’m here to kick ass

Her specific field is marine plankton fossils, and while she accepted the asteroid strike theory from when she first got into the field, she’d stayed clear of all the fighting.

That changed over time. First, a paleontologist friend who worked on other time periods argued that of course both the asteroid and volcanism were responsible. “I remember feeling so irritated,” Hull said. “This isn’t your topic of study; how do you have an opinion on this?”

Yeah! What is it with experts in one field who think they can poke their nose into other fields. You keep doing that and pretty soon you’ll have nuclear physicists pushing paleontologists around and statisticians bullying epidemiologists. 😉

…there were two papers that were published in 2019. They used two different geological chronometers to date the Deccan Traps,

And I realized that this is my moment. We can use my seafloor data to actually test these two hypotheses.

Fossils of Marine Plankton, roughly salt grain sized.

What she found with her data was that the plankton had gradually moved towards the poles of the earth over a period of about 200,000 years because the planet was warming up, almost certainly due to the Deccan Traps volcanic eruptions. But then they move back towards the equator because the planet was cooling. And then everything changed at once:

The boring story is that you’re looking at the late Cretaceous for millions of years. Climate goes up, it gets a little warmer, or colder, warmer, colder. But effectively, there’s nothing much to talk about. And then right at the impact, all the records go haywire.

They do show a slight warming and a slight cooling. But it’s nothing to write home about. The only thing that really jumps out at you is: Look at the impact. Everything in the deep sea goes crazy.

We’ll see what Ms. Keller does with this, since much of her evidence is based on another sea-based form of life: forum (technically Foraminifera):

Three hundred thousand years before Alvarez’s asteroid struck, some foram populations had already started to decline. Keller found that they had become less and less robust until, very rapidly, about a third of them vanished. “My takeaway was that you could not have a single instantaneous event causing this pattern,”

Forum fossils vs plankton fossils! Who will win? Much as admire Ms. Keller I think this is yet another nail in the coffin of her volcano theory.

Written by Tom Hunter

April 9, 2020 at 10:01 pm

Posted in Science, Space

Tagged with , , ,

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