Additional Coverage:
New Research Suggests Dinosaurs Thrived Until Asteroid Impact
For decades, paleontologists have debated whether dinosaur populations were already dwindling before a massive asteroid struck Earth 66 million years ago, leading to their mass extinction. Now, new research offers a compelling piece of the puzzle, suggesting that dinosaurs in North America were flourishing right up until the catastrophic impact.
While independent experts caution that this is just one piece of a global picture, the findings indicate a vibrant and diverse dinosaur community roamed the continent before their abrupt demise. “Dinosaurs were quite diverse and now we know there were quite distinct communities” in existence prior to being wiped out, stated Daniel Peppe, a study co-author and paleontologist at Baylor University.
The latest evidence comes from a century-old treasure trove of dinosaur fossils within a section of the Kirtland Formation in northern New Mexico. Scientists have now precisely dated these fossils and the surrounding rock to approximately 400,000 years before the asteroid strike – a mere blink in geological time. This age was determined by meticulously analyzing volcanic glass particles embedded in sandstone and studying the orientation of magnetic minerals within the formation’s mudstone.
“The animals deposited here must have been living close to the end of the Cretaceous,” the final era of dinosaurs, Peppe explained. The groundbreaking findings were published Thursday in the journal Science.
Intriguingly, the dinosaur species identified in New Mexico differ from those found at a Montana site previously dated to the same timeframe. This distinction, Peppe notes, “run counter to the idea that dinosaurs were in decline.” Among the fossils unearthed at the New Mexico site are the fearsome Tyrannosaurus rex and a horned herbivore akin to a Triceratops.
One of the study’s most significant subjects was the colossal plant-eating Alamosaurus, which could tip the scales at over 30 tons and stretch nearly 100 feet long. Steve Brusatte, a paleontologist at the University of Edinburgh and study co-author, emphasized the significance of its presence: “Nothing illustrates how dinosaurs were thriving up to the very end more than the fact that Alamosaurus, one of the biggest dinosaurs ever – in fact, one of the very biggest animals to ever live on land in the entire history of the Earth – was there to witness the asteroid.”
Brusatte painted a vivid picture of the scene: “So not only were sauropods still around when the asteroid hit, they were still thriving, still sublime, still colossal, still glorious. I can imagine the scene: one minute, a jet plane-sized dinosaur was shaking the ground as it walked, the next minute the whole Earth was shaking with the energy unleashed by the asteroid.”
A 2019 research team previously detailed the immediate aftermath of the asteroid strike, which unleashed a chaotic day of widespread fires, earthquakes, and tsunamis, followed by a prolonged period of global cooling.
However, scientists not involved in the current study urge caution in drawing broad conclusions from a single location. “This new evidence about these very late-surviving dinosaurs in New Mexico is very exciting,” commented University of Bristol paleontologist Mike Benton. Yet, he added, “This is just one location, not a representation of the complexity of dinosaur faunas at the time all over North America or all over the world.”
Accurately dating dinosaur fossils presents a unique challenge, as easily datable materials like carbon do not endure within fossils. Scientists must instead rely on surrounding rocks with specific characteristics to determine their age, explained Andrew Flynn, a paleontologist and study co-author from New Mexico State University.
Further research, Flynn believes, will be crucial in completing the global picture of dinosaur diversity on the eve of the asteroid’s devastating impact.