How were scientists able to come to the (pretty much universally accepted) conclusion that it was a meteor that killed the dinosaurs when no one was around to witness it?

Question

Is it even remotely possible it was something else that happened around the same time?

In: 0

Answer 1

This is actually a relatively recent consensus that has formed in the scientific community. There was a lot of speculation over the years about why the Dinosaurs disappeared, and nobody was exactly sure if it was a sudden catastrophic event (i.e. volcanic eruptions, asteroid impact event) or something more gradual (climate change).

In 1980 some geologists discovered a thin layer of sediment in the Earth’s crust that had a lot more Iridium in it than there should be – this came to be known as the K-T boundary (now it’s called the K-Pg boundary). It turns out that this is what you’d expect to happen if there was a really big asteroid impact – they have a lot more Iridium than normally occurs in the Earth’s crust. When they got rough estimates of the age of this layer, it lined up with the time that the Dinosaurs disappear from the fossil record. So they hypothesized that a massive asteroid impact was responsible for this extinction event. The only problem was that there wasn’t any known crater on the planet that was the right size and age to fit the hypothesis.

About 10 years later, geologists found a structure around the Yucatan peninsula in Mexico that corresponded to an impact crater that was the right size and age for this particular impact. Some additional research in 2016 got material samples from the crater and have pretty much confirmed that this was the impact event that caused the K-Pg boundary – and this the most likely reason for the disappearance of the Dinosaurs.