From our standpoint 66 million years later, it's easy to assume the demise of the dinosaurs was an inevitability.
That conclusion makes up one of the most intriguing revelations in “The Day the Dinosaurs Died,” a BBC Two documentary that was filmed across three continents during the past year before airing this week.
How is it possible dinosaurs could still be alive?
If the massive asteroid that smashed into present-day Yucatan hit the Atlantic Ocean or somewhere else, the scientists maintain, the rock would have avoided an area made up primarily of limestone and evaporated ocean sediments and rich in carbon dioxide, sulfur and deadly gypsum. Due to the earth's rotation, even a minute or two could have significantly changed the outcome of the impact.
It was, for all intents and purposes, a kill shot for the giant reptiles roaming the planet.
“When the asteroid hits with the force of something like 10 billion Hiroshima explosions, all of that gets pumped up in the atmosphere, and it may have been really critical for the mass extinction that followed as it blocked out the sun,” Sean P. Gulick, a University of Texas professor who studies catastrophism in the geologic record, told The Washington Post. “A few minutes earlier or later and the asteroid would've hit the Atlantic or the Pacific Ocean and not slammed into a big, volatile platform that was then vaporized as it spread upward and out.”
Known as the Chicxulub crater, the impact zone lies 24 miles off the Yucatán Peninsula in Mexico. The impact left in its wake a hole in the Earth 20 miles deep and 120 miles across, scientists say, a site that is now covered completely by 66 million years worth of solid rock and sediment.
To reach their shocking conclusion, the scientists drilled through that rock and into the site of impact crater more than 1,300 meters below the seafloor. Gulick, who appears in the BBC Two program, said drilling into the crater is something he's been pushing for, with grant proposals and lobbying, for more than 15 years.
“The idea was a little outside of the box,” he said. “When scientists are seeking funding, most of the time people are going after some question about past climates or earthquakes or some very fundamental ocean earth science topic, but we were saying we wanted to drill into an impact crater, which has a different ring to it.”
“It just so happens that this particular crater had an extremely important role in the history of our planet,” he added.
Though many scientists say the impact of an asteroid caused many dinosaurs to vanish, the idea remains a widely accepted theory. Using seismic images that showed researchers where they could find the crater's central impact zone, known as the “peak ring,” the scientists said they were looking for physical evidence to bolster the theory.
With that in mind, they had three different goals:
1. Better understanding physical processes that shape impact craters.
2. Investigating the different “kill mechanisms” in place, such as the type of material released into the atmosphere, that may have caused the extinction of the dinosaurs.
3. Studying the microbial life that moved into the subsurface in the wake of the impact.
Eight weeks of intensive drilling were required to collect more than 260 rock cores, which were extracted and taken to the University of Bremen in Germany for examination, according to BBC Two.
That analysis — requiring 800 meters of rock being split, tested and photographed — resulted in some extraordinarily detailed insights. The scientists believe they have proved that the asteroid that smashed into the Yucatan Peninsula was moving at 40,000 mph and instantly vaporized upon hitting the water.
It was, BBC Two notes, the equivalent of a grain of sand slamming into a bowling ball, but the impact was so powerful and hot that it turned the surrounding sea to steam and traveled miles into the earth's crust. The rock that was pushed upward, the scientists found, formed “a tower higher than the Himalayas” before collapsing to “form a strange ring of peaks that exists today,” according to BBC Two.
All of it, the researchers found, took place in the space of 10 minutes.
“It's an amazing oceanographic event, even more so because we see in the cores that life came back pretty quickly,” Gulick said. “We discovered that organisms started to evolve within the sea floor at the crater within a few tens of thousands of years — we know for certain by 30,000 years.”
What followed immediately after the impact was a scene reminiscent of a modern-day nuclear holocaust, mixed with profound natural disasters on a mind-boggling scale.
A radioactive fireball that reached 18,000 degrees scorched the Earth for 600 miles in every direction and unleashed the largest tsunami in history, Gulick said. A deadly vapor containing billions of tons of sulfates fanned out over the globe, blocking sunlight and lowering temperatures, while molten material from the crater rained down upon the Earth for thousands of miles in every direction, starting fires and turning the atmosphere into an oven, according to BBC Two.
Ben Garrod, an evolutionary biologist who appears in the program, said global temperatures plunged more than 50 degrees within days.
“This is where we get to the great irony of the story — because in the end it wasn’t the size of the asteroid, the scale of blast, or even its global reach that made dinosaurs extinct — it was where the impact happened,” Garrod said.
“In this cold, dark world, food ran out of the oceans within a week and shortly after on land,” he added. “With nothing to eat anywhere on the planet, the mighty dinosaurs stood little chance of survival.”
The dinosaurs' sudden ending did have an upside, according to Alice Roberts, a professor of public engagement in science at the University of Birmingham, who appears throughout the documentary.
“Just half a million years after the extinction of the dinosaurs and landscapes around the globe had filled with mammals of all shapes and sizes,” she said. “Chances are, if it wasn’t for that asteroid, we wouldn’t be here to tell the story today.”