Although most dinosaurs disappeared 65 million years ago, birds continued to flourish. During the Cenozoic—the era that followed the age of the dinosaurs—birds evolved into a vast range of new species. Some became masters of the sky or took to the water. Others gave up flying and evolved into huge carnivores, filling the gap that the dinosaurs had left open.
■ When: 5–2 million years ago (Neogene)
■ Fossil location: North and South America
■ Habitat: Grassy plains
■ Height: 8 ft (2 m)
■ Diet: Meat
Also known as a “terror bird,” Titanis was a gigantic, flightless carnivore as fearsome as a dinosaur. It was twice the weight of a man but much faster, capable of running at up to perhaps 40 mph (65 kph). It used a huge, hooked beak to kill prey and rip open their bodies. Titanis lived at the same time as prehistoric humans were beginning to walk on land and spread, but the two never met as Titanis lived only in the Americas. Among its prey was the prehistoric horse Hipparion.
■ When: 2 million–200 years ago (Neogene)
■ Fossil location: New Zealand
■ Habitat: Plains
■ Height: 12 ft (4 m)
■ Diet: Plants
Twice the height of a man, Dinornis (also called the giant moa) was the tallest flightless bird that ever lived. Flocks of Dinornis lived in New Zealand until humans settled on the islands about 700 years ago and hunted them to extinction.
Dinornis belonged to the same bird family (ratites) as the emu, ostrich, and kiwi.
■ When: 6 million years ago (Neogene)
■ Fossil location: Argentina
■ Habitat: Inland and mountainous areas
■ Wingspan: 26 ft (8 m)
■ Diet: Meat
Argentavis was the largest bird that ever flew, with a wingspan more than twice that of today’s record holder, the wandering albatross. As heavy as a man, it used its vast wings to catch rising air currents and so keep its body aloft, gliding effortlessly as it scanned the landscape for food. Some experts think Argentavis was a hunter that could swoop down and snatch prey. Others think it scavenged like a vulture.
■ When: 62–55 million years ago (Paleogene)
■ Fossil location: N. America, S. America, Europe
■ Habitat: Lake shores
■ Height: 3 ft (1 m)
■ Diet: Plankton, water plants Presbyornis looked like a tall duck. Large numbers of fossils, as well as eggs and nests, have been found in sites in North America that were once shallow lakes.Perhaps Presbyornis lived in huge flocks by the shore, the birds wading into the shallows to feed, using their beaks to filter food from the water, as ducks do. Presbyornis was one of the most successful birds of its time, living for millions of years.