Paleontologist Robert DePalma has done it again. After his excavations at the Tanis site in North Dakota unearthed a huge trove of fish fossils that were likely blasted by the asteroid impact that made the dinosaurs go extinct 66 million years ago, the postdoc researcher from the University of Manchester now claims he has found a fragment of this doom-bringer encased in a piece of amber, nature's time capsule.
A dinosaur graveyard
The asteroid that struck Earth offshore Mexico's Yucatan Peninsula was simply devastating to all life on Earth, not just the dinosaurs. The cosmic impact unleashed the force of 10 billion Hiroshima A-bombs and released gigatons of sulfur and carbon dioxide, which could have lowered surface air temperatures by a staggering 26 degrees Celsius (47 degrees Fahrenheit). This global winter lasted for years, enough to devastate plant life and everything else along the food chain. Around 75% of all animals and plant species went extinct, including the iconic dinosaurs (except for birds).
In 2019, DePalma and colleagues found that a massive surge of water must have fallen upon Tanis as a result of a vast earthquake triggered by the asteroid impact, rapidly depositing sediments that covered all sorts of animal remains, including fish, a turtle impaled by a stick, and a leg that could have belonged to a dismembered dinosaur that witnessed in the asteroid strike in real-time.
Today's dusty endless plains at the Tanis site looked radically different during the Cretaceous Period, during those ominous days right before the asteroid impact. Back then, the entire Midwest was largely a swampy rainforest, with a huge inland sea called the Western Interior Seaway running from the Gulf of Mexico to Canada.
This region was probably teeming with life until the cosmic impact changed everything. But the dinosaurs and other animals weren't killed as a result of the direct impact, which occurred more than 2,000 miles (3,200 km) away. Instead, most in this area were likely wiped out by the displacement of massive sediment debris as a result of moving water bodies from the interior seaway. These water waves weren't technically tsunamis, which are slower to develop after an earthquake, but rather the more instantaneous variety called seiches.
Like Sherlock Holmes, DePalma used the various bits of seemingly unrelated evidence found at the site to reconstitute the final days of the creatures leaving there. He's certain the large number of animals that look like they were all killed at the same time did not die as a result of massive wildfires or the nuclear winter that would ensue in the coming months. His smoking gun is the presence of impact spherules, which are small bits of molten rock from the impact crater blasted up into the atmosphere, where they quickly crystallize into a glass-like material. Some of this material, which is preserved as clay due to water infiltration over millions of years, was found lodged in the gills of fish.
But some of these spherules also landed in tree resin, some of which were preserved in amber.
"In that amber we've located a number of spherules that were basically frozen in time, because, just like an insect in amber which is perfectly preserved, when these spherules entered the amber, water couldn't get to them. They never turned to clay, and they're perfectly preserved," DePalma told CNN.
A smoking gun
Most of these tiny rock fragments that the researchers have managed to find in amber were rich in calcium, pointing to the limestone beneath the Yucatan Peninsula. But two other fragments contained chromium and nickel, as well as other elements commonly found in meteorites. These fragments "are almost certainly of cosmic origin", according to DePalma.
This could prove mindblowing and a major landmark in paleontology if confirmed. These findings have yet to be peer-reviewed in a paper, which is expected to happen in the coming months. However, the findings have already been brought to the attention of NASA, after DePalma held a presentation at the Goddard Space Flight Center in Greenbelt, Maryland.
While we wait for the potentially historic paper to pass peer-review, you can learn more about the extraordinary discovery from Tanis in a new documentary narrated by Sir David Attenborough, called "Dinosaur Apocalypse." The show premiered on PBS last week and can be watched online. Besides the asteroid fragments, the documentary also involves a preserved dinosaur leg with skin still intact, which suggests the dead tissue did not have time to decay after it was buried by sediments; a fossilized pterosaur egg; and a fossilized turtle with a wooden stick still lodged in its body, probably impaled during the water surge caused by the asteroid strike.