I can vividly remember sitting in my second grade classroom, debating with my teacher about what had killed the dinosaurs so many moons ago. There I was, seven or eight at the time, arguing that Earth's former reptilian planetary overlords were killed off by an asteroid impact, whereas my teacher attempted to correct my view, arguing in favor of climate changes in the ancient world that led to an ice age.
Part of the reason that there had been such room for argument, especially at that time, is because up until the early 1980s there still weren't conclusive theories about what might have caused a mass-extinction of the magnitude that led to the death of the dinosaurs.
However, the eventual discovery of traces of iridium in the geological boundaries between the Cretaceous and Paleogene eras would offer clues to the mystery. The iridium traces were presented as an argument by physicist Luis Alvarez and his son Walter, a geologist, forming the basis of what became known as the Alvarez hypothesis: in a nutshell, the father-son duo believed that since iridium is rare on our planet, and therefore most often found on Earth only with the discovery of objects of extraterrestrial origin, the anomalous amounts of the stuff at the Paleogene boundary suggested something from space--and probably something very large--had brought it here.
Thus, the Alvarez hypothesis moved that an asteroid impact had likely been what killed the dinosaurs, pinpointing an area of the Yucatan Peninsula near Chicxulub, Mexico, as the likely asteroid impact site.
Prior to the asteroid impact hypothesis becoming the leading theory behind dinosaur extinction, it had long been noted that volcanic disturbance in other parts of the world, particularly in modern day India, had been a likely candidate as well. Once scientists began to seriously consider an asteroid impact in 1980, some suggested a possible link between the two; however, geological evidence shows that the volcanic eruptions occurring in India must have begun prior to the Chixulub event, and hence they obviously couldn't have been caused by it. The question remained, however, as to whether the volcanic activity occurring at roughly the same time may have still been a factor, and whether its vastness could still be linked with the asteroid in some way.
Now, scientists with Princeton University believe that this is precisely the case, and that while the massive volcanic activity occurring in India at that time may not have been the result of an asteroid hitting the earth, this event probably did little to settle the geological volatility that was already underway.
According to the Washington Times:
Gerta Keller, a Princeton geologist who has long championed the idea that the volcanism, and not the Chicxulub impact, led to the mass extinctions, said in an email that “there is still the big problem of demonstrating that this impact could have triggered the intense eruptions that led to the mass extinction.”
The new research could point to an eventual reconciliation of the two views, Renne and Richards believe. Both camps could both be right to some degree. First came the blow from space, which incited the blow from the Earth’s molten interior.
It is not impossible, of course, that the sorts of fortuitous circumstances which led to apocalyptic scenarios like this in the ancient world might happen again. With our present technologies, humanity now sends probes out into space that follow and, eventually, plant themselves on asteroids, through which we seek to learn about the extraterrestrial environments they may be harboring. Yet the same technology might not be capable of offsetting the course of such a massive space rock, let alone destroying it, or preventing it from destroying us.
As we continue to learn new things about the ancient world, we are reminded of the ever-present threats to life on Earth that still exist. In turn, we are also faced with the possibility that destructive forces that exist already may be strengthened by an extraterrestrial catalyst, the likes of which brought an end to one of the most fascinating and diverse periods in which life existed on our ancient planet.