When you think of a scary dinosaur, what comes to mind? The agile, sickle-clawed Utahraptor? A towering Tyrannosaurus? Something as alien as the croc-snouted, sail-backed Spinosaurus, perhaps? Books and museum halls are well-stocked with such Mesozoic nightmares, but scary dinosaurs have also stalked the land in the days after the end-Cretaceous mass extinction. There’s an entire group of fossil dinosaurs – technically known as phorusrhacids – that are imposing enough that paleontologists often call them by a more evocative name. These were the terror birds.

There aren’t any terror birds around today. The first evolved around 62 million years ago and the last perished about 2.5 million years ago, most of them playing the part