Phorusrhacos (Phorusrhacos longissimus). Artwork of a pair of Phorusrhacoses attacking the prehistoric mammal Doedicurus clavicaudatus. Phorusrhacos is an extinct giant flightless bird that lived in Patagonia during the Miocene (23 million - 5 million years ago.) It stood 2.5 metres tall and it's huge curved beak and sharp claws suggests it had a carnivorous diet. It is distantly related to modern day seriema birds.