WE NOW KNOW MORE ABOUT THE DAY THE DINOSAURS DIED
In March, palaeontologists led by Robert DePalma were digging in the Hell Creek region of North Dakota in the US, when they found a fossilised dinosaur leg. That in itself was not unusual, as the region has long been known to be rich in fossil deposits. But this particular dinosaur, a Thescelosaurus, is believed to have been killed in the asteroid strike that wiped out the dinosaurs around 66 million years ago.
This makes it unique in the fossil record. In fact, until just a few years ago, no fossil had been found that lived even around the time of the impact. While debris and ash from the event shows up in core samples as a thin layer of dark sediment known as the KT (or K-Pg) boundary, no fossils had ever been found in the layers immediately below that, which represent a million years or so of evolution.
Dinosaurs could therefore, in theory, have died out thousands of years before the impact. But in 2013, DePalma was digging in an area of Hell Creek when he unearthed fish fossils buried in the same stratum as microtektites. These are beads of glass that form when molten rock is blasted into the air by an asteroid impact and then rains back down, solidifying as it falls. DePalma realised he had stumbled upon a geological snapshot of the extinction event itself and has since found many more fossils at the top-secret site,
