Theories Explaining the Demise of the Dinosaurs
The chapter of life which saw the rise of the dinosaurs is one of the most fascinating periods in our earth’s history. It is often the subject which brings about young children’s first exposure to science. When these children learn about these intriguing prehistoric beasts, one of their primary inquiries concerns the cause of their annihilation. What could have led to the demise of all those creatures, who lived very successfully for millions of years? This question has plagued experts and curious children alike for decades. In the early 1990s, a “smoking gun” was discovered – purported to solve the mystery of how the dinosaurs met their fate. This discovery was the Chicxulub crater in Yucatan, Mexico. The claim was that this 180 kilometer crater was the impact scar left by an asteroid that collided with the earth. The asteroid was so large and landed with such force that it effectively ended the dinosaurs reign over the earth. However, recent evidence and research reported in Proceedings of the National Academy of Sciences suggests that this could not have been the case, because the Chicxulab crater predates the mass extinction by roughly 300,000 years. Rather, the evidence suggests that two or more impacts caused the mass extinction experienced by dinosaurs.
Fossil records inform us that the mass extinction occurred 65 million years ago. This landmark coincides with and marks the Cretaceous-Tertiary (K-T) boundary. There appeared to be relative consensus among scientific professionals that an asteroid impact caused the mass extinction. According to this theory, “debris from the asteroid’s impact would have superheated the atmosphere so that vegetation burst into flames over much of the planet … ground temperatures soared to about 1000C, igniting forest fires across the world and boiling land organisms alive. The soot and smoke thrown into the atmosphere may have helped block sunlight, causing global cooling and plunging the planet into winter.i” However, the location of the impact is more elusive than the media and scientists initially made it appear. In order for a crater to be conclusively labeled the primary cause of the mass extinction, data would have to reveal not only that it had the necessary force and magnitude, but that it is from the right period in geologic time.
A team of international scientists sought to prove or disprove that the Chicxulub crater occurred at the right point in time to have caused the mass extinction. This group was led by Gertra Keller, professor at Princeton University. They tested a previously uninvestigated core within the Chicxulub crater, known as “Yaxcopoil-1.” According to the group’s reported findings, evidence proved a pre-K-T impact occurred. This was “based on five independent proxies, each with characteristic signals across the K-T transition: sedmentology, biostratigraphy, magneto-stratigrophy, stable isotopes,...