Tiny dinosaurs have been trending this December. There was the paleontologist who wants to reverse engineer tiny velociraptors in the name of research. Then the internets became all aflutter with bunny dinosaur – Aquilops americanus.
But, the real scoop this month is not in the discovery of dinosaurs. Gerta Keller dropped a new paper that fills in more details about their extinction.
It was just like a new album. But you know. Not at all.
For those of you who are not totally invested in this awesome story, you should know that it is like the Miley Cyrus/Sinead O’Connor feud of paleontology. But way smarter.
In the 1980s, father-son duo Walter and Luis Alvarez suggested that a giant meteorite collided with the Earth sixty-five million years ago and wiped out half of all species of plants and animals, including the mighty dinosaurs. In this analogy, Luis Alvarez is kind of like Billy Ray Cyrus. Except, Luis Alvarez is a nuclear physicist and won the Nobel Prize for Physics.
Their evidence? When they were trying to date a thin layer of dirt at the Cretaceous-Paleogene boundary they found out it was full of Iridium. Iridium accretes in soil slowly, as it dribbles down to Earth in the form of meteorite dust. No Iridium would have suggested to the Alvarez team that the thin layer of dirt corresponded to a small period of time. Small amounts of Iridium would have indicated a longer time period. Lots of Iridium? ZOMG, a meteor strike!
Big name backing with a flashy theory and fantastic costuming, er, imagery. Bam! The Alvarez theory tops the charts. It’s part of our cultural zeitgeist. Everyone knows that a meteor killed the dinosaurs!
But, Princeton prof Gerta Keller, was working on the mass extinction at the Cretaceous-Paleogene boundary before the Alvarez team ever caught the gleam of meteor-proving Iridium. And damn it, her microscopic, oceanic fossilized foraminifera were screaming: gradual and selective extinction event.
Lines were drawn, allies were made, papers flew, and (we swear we are not making this up) a “blind” test of the oceanic microforam was conducted in the pages of Marine Micropaleontology. But the popularity of the Alvarez theory was overwhelming. It has that elegance that scientists love.
Yet, Gerta Keller never gave up. She has doggedly pursued an alternate theory for thirty years. Her theory doesn’t dismiss the possibility of a large meteor strike, instead Keller argues that any possible asteroid impact was essentially a coup de grâce of an extinction trend that was far more gradual – although no less spectacular. Keller believes the extinction event was caused by climate change as a result of massive volcanic eruptions. These eruptions created the Deccan Traps – an igneous rock formation covering 200,000 square miles of India. Keller maintains that thousands of years of volcanic activity spewed sulphur and carbon dioxide into the atmosphere creating global warming and acidification of the oceans.
And now she has delivered her own smash hit single: a high-resolution eruption timeline for the Deccan Traps. Without accurate dating, it’s been difficult to fully assess the relationship between the volcanic activity at the Deccan Traps and the mass extinction event. But this new publication Keller et. al. illustrates just how significant these volcanic eruptions were, and how close they were to the boundary.
The volcanic activity is now thought to have lasted over 700,000 years with almost no hiatus. That’s a hell of a lot of erupting. Keller was also able to show that eruption cycle began 250,000 years prior to the shift from the Cretaceous period to the Paleogene period and continued throughout the shift.
Professor Keller, we salute your continued search for complex and nuanced answers.
Your move, impact supporters, your move.
The paper cited throughout this post is: Blair Schoene, Kyle M. Samperton, Michael P. Eddy, Gerta Keller, Thierry Adatte et. al. (2014) “U-Pb geochronology of the Deccan Traps and relation to the end-Cretaceous mass extinction” Science.
If you would like to read a more thoughtful and detailed version of this scientific debate, we recommend: The Great Dinosaur Extinction Controversy