New evidence found for the asteroid that deep-sixed the dinosaurs

It had to be something spectacular:

Rocks from the most pivotal moment in Earth’s history were discovered offshore of the Yucatan Peninsula, according to a study released Monday.

The finding is “the most detailed look yet into the aftermath of the catastrophe that ended the Age of Dinosaurs,” said study lead author Sean Gulick, a research professor at the University of Texas Institute for Geophysics.

When the asteroid smashed into the Earth 66 million years ago, the impact ignited wildfires, triggered tsunamis and blasted so much sulfur into the atmosphere that it blotted out the sun, which caused the global cooling that killed off the dinosaurs.

Doyle Rice, “Rocks discovered from the day the dinosaurs died 66 million years ago when an asteroid hit the Earth” at USA Today

It’s certainly valuable new information. The outstanding puzzle has always been, why were all dinosaurs killed off but not all mammals or reptiles?

Most of the material that filled the crater within hours of impact was produced at the impact site or was swept in by seawater pouring back into the crater from the surrounding Gulf of Mexico.

In just one day about 425 feet of material was deposited – a rate that’s among the highest ever encountered in the geologic record.

This breakneck rate of accumulation meant the rocks recorded what was happening in the environment within and around the crater in the minutes and hours after impact and provide clues about the longer-lasting effects of the asteroid strike.

The research details how the blast from the impact ignited trees and plants stretching thousands of miles away and triggered a massive tsunami that reached as far inland as Illinois (over 500 miles).

Harry Cockburn, “Dinosaur extinction: Asteroid hit with force of 10 billion atomic bombs and deposited ‘hundreds of feet’ of material in hours, new research says” at Independent

Cores from Chicxulub crater reveal the planet-wide devastation that the large impactor caused, but the timing of these events will likely spur debate and discussion, Witts says. “The complication with relating individual deposits in the core to specific types of events is that clearly the crater wasn’t a static environment after formation,” Witts says, meaning that earthquakes, waves and other events have altered the rock record over the course of 66 million years. Still cores like the one taken from the peak ring show that we can get a close-up look at short-term events in the rock record, down to minutes, hours and days.

Scientists knew the first day of the Cenozoic started with a bang, and now they have a better sense of the fallout

Riley Black, “What Happened the Day a Giant, Dinosaur-Killing Asteroid Hit the Earth” at Smithsonian Magazine

Paper.

See also: Learning more about the asteroid that doomed the dinosaurs

and

One approach to the extinction is “dino diminuendo” — they were dying out anyway; the asteroid deep-sixed them much quicker. See, for example:

Smithsonian: The Asteroid Strike Was Only One Factor In Dinosaur Extinction

The Atlantic: “Nastiest feud in science” erupts over dinosaur extinction theory

In the past, the field has been littered with speculations such as that dinosaurs were dumber than mammals and did not look after their young. But we now know that some dinosaurs did look after their young and that the capacity to do so is much older than formerly thought. Also that placental mammals are not uniformly smarter than all other life forms.

Extinction: Had the dinosaurs been dying out before the big K-T extinction?

Dino diminuendo (They were dying out before the asteroid hit.) That might help account for why all dinosaurs disappeared but only a large proportion of other vertebrates.

Smoking did not kill the dinosaurs, but dark matter might have contributed

Dinosaurs doomed by egg-laying?

Size helped largest dinos survive longer?

Do mass extinctions happen every 26 million years or so?

Study: Two years’ darkness provides a clue to total dinosaur extinction

and

We can’t understand evolution without understanding stasis and extinction

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