Our species hasn't been around long enough to experience a cataclysmic extinction event.

CNN: Space's threat to civilization

Either it's going to become multiplanetary, or it's going to be confined to one planet until some eventual extinction event.

WSJ: An Electric Car and a Trip to Mars

Scott Kenemore, author of "The Zen of Zombie" and a member of the advisory board of the Zombie Research Society, said the zombie apocalypse can represent a validation of sorts for people awaiting their particular extinction event.

CNN: Apocalypse believers' big finish predictions vary

Unless action is taken now, the consequences of our activities are at a high risk of causing, through the combined effects of climate change, overexploitation, pollution and habitat loss, the next globally significant extinction event in the ocean.

FORBES: A Call to Arms on Climate Change

Besides bringing new species to the textbooks - and relegating them immediately to the "extinct" category - the study sheds new light on the extinction event, widely thought to have been caused by an enormous asteroid impact at the end of the Cretaceous period, about 65.5 million years ago.

BBC: Obama-named lizard was wiped out with the dinosaurs

The question is one of the most hotly contested in palaeontology and revolves around an apparent gap in the fossil record immediately prior to the K-T boundary - the distinct layer of geological sediments separating the Cretaceous and Tertiary periods, and associated with a massive asteroid impact and global extinction event.

BBC: Closing the 'three metre gap'

But not when your expectations have been raised to extinction-event-size asteroid objects.

WSJ: At the Intersection of Yoko and Idaho

By "they", I refer to the thinkers and tacticians at the Treasury who are suggesting that Scottish banknotes may face extinction in the event of independence.

BBC: Malachi Malagrowther and the Scottish banknote