About 66 million years ago — perhaps on a downright unlucky day in May — an asteroid smashed into our planet.
The fallout was immediate and severe. Evidence shows that about 70% of species went extinct in a geological instant, and not just those famous dinosaurs that once stalked the land. Masters of the Mesozoic oceans were also wiped out, from mosasaurs — a group of aquatic reptiles topping the food chain — to exquisitely shelled squid relatives known as ammonites.
Even groups that weathered the catastrophe, such as mammals, fishes and flowering plants, suffered severe population declines and species loss. Invertebrate life in the oceans didn’t fare much better.
But bubbling away on the seafloor was a stolid group of animals that has left a fantastic fossil record and continues to thrive today: bivalves — clams, cockles, mussels, oysters and more.
What happened to these creatures during the extinction event and how they rebounded tells an important story, both about the past and the future of biodiversity.
