Sixty-five and a half million years ago, dinosaurs vanished from the earth. The fate of these magnificent beasts remains a mystery to this day. However, new evidence has recently emerged that might help solve this mystery once and for all. So, what killed the dinosaurs?
Dinosaurs & the Mysterious K-Pg Boundary?
Dinosaurs roamed the earth for about 160 million years, encompassing large parts of the Jurassic and Cretaceous Periods. While the size, shape, and features of dinosaurs varied extensively, they all share one thing in common. Sixty-five and a half million years ago, all non-avian dinosaurs perished in the Cretaceous-Paleogene extinction event, or the K-Pg extinction event. The K-Pg boundary is a layer of sediment in the earth’s crust that marks the switch from the Cretaceous Period (K) to the Paleogene Period (Pg). Non-avian dinosaur bones are never found above this layer, which indicates that dinosaurs became extinct at or before the same time it was created.
Did an Asteroid or Comet Kill off the Dinosaurs?
In 1980, the father/son team of Luis and Walter Alvarez discovered that the K-Pg boundary contained iridium, an element not usually found in the earth’s crust. After eliminating other possible sources, they concluded that the iridium most likely arrived via comet or asteroid. Although hotly contested at first, this theory later found broad acceptance due to the announced discovery of the Chicxulub Crater. The crater, located under Mexico’s Yucatán Peninsula, measures over 110 miles in diameter. Most scientists today believe that an asteroid or comet, measuring over six miles in diameter, impacted the earth sixty-five and a half million years ago. In the process, it created the crater and drove the dinosaurs to extinction.
The Problematic “Fossil Gap”?
However, not everyone believes the official story. These individuals point to the fact that dinosaur bones become less frequent as they approach the K-Pg boundary. Also, there is a “fossil gap” since no bones have ever been found within the boundary itself. Taken together, these things indicate that the extinction predated the impact at Chicxulub. If this is the case, then dinosaurs were probably killed off more gradually, by things such as a volcanic winter, the Deccan traps, falling sea levels, and/or climate change.
That brings us to the present. While working in Montana, a team of Yale scholars recently discovered a dinosaur bone just thirteen centimeters below the K-Pg boundary. This marks the closest a bone has ever been found to the boundary, beating the old record by twenty-four centimeters. The discovery, made by Yale anthropologist Eric Sargis and graduate student Stephen Chester, indicates that dinosaurs were still alive a few thousand years before the impact event.
“Here we have a specimen that basically goes right up to the boundary, indicating that at least some dinosaurs were doing fine.” ~ Tyler Lyson, Paleontologist, Yale University
Guerrilla Explorer’s Analysis
The discovery is exciting and lends weight to the theory that dinosaurs were still alive at the time of the impact event. However, it hasn’t ended the debate as to what killed the dinosaurs. This particular bone could’ve easily belonged to one of the few remaining dinosaurs as they gradually became extinct. Unfortunately, without more bones there’s no way to be sure.
In March 2010, forty-one experts from across the globe reviewed evidence in the fields of paleontology, geochemistry, climate modeling, geophysics, and sedimentology. They concluded that a giant asteroid caused the Chicxulub crater, triggering mass extinctions of the dinosaurs. So, it would appear that there is a sort of scientific consensus in support of the impact theory.
But does that even matter? History is full of scientific consensuses that were later overturned. Heck, thirty years ago, no one believed that an asteroid caused dinosaurs to go extinct. Now, its the most popular opinion. Who knows what the next thirty years will bring?