What are Ratites?
Ratites are an unusual group of flightless birds of Gondwanan distribution (South America, southern Africa, and Australia). Being named for the Greek word for raft (ratis), ratites have no keel on their sternum, meaning that they have no place to attach wing muscles. For this reason, they couldn't fly even if they had the wings for it. Ratites evolved sometime between 130 and 80 million years ago, though the oldest ratite fossil known is 60 million years old. Scientists know that they evolved earlier than 60 million years ago because ratites are found on continents that had become widely separated by then, and they could not have spread from continent to continent by swimming across the ocean.
As the group that includes the ostrich, rhea, cassowary, the ratites are quite diverse, but are known for including the largest living bird, the African Ostrich, which can be 3 meters (10 ft) tall, weigh 159 kg (360 lb), and can outrun a horse (46 mph, 74 km/h) . The African Ostrich also produces the world's largest eggs, 6 in (15 cm) long, 5 in (13 cm) wide, and weigh 3 lb (1.4 kg). In stark contrast is the Little Spotted Kiwi, a small, chicken-sized bird that lives in Australia.
Alongside the Ostrich, the most famous ratites are the kiwis, endangered birds native to New Zealand. As small, flightless birds, kiwis are highly vulnerable to mammalian predators like rats, cats, and dogs, but thankfully for them, these animals are rare in their small ranges in New Zealand. For tens of millions of years, New Zealand has lacked any mammalian predators (the only endemic mammals are three bat species), allowing the kiwis to evolve in peace. Their iconic look, with a long beak designed to probe rotting wood for insects, has made them a national symbol of New Zealand. Kiwis have vestigal wings so small that they are mostly hidden by their body feathers.
An extinct ratite, the Elephant Bird of Madagascar, was the world's largest bird at the time when it lived, though it went extinct in the 16th century. On average, these birds were about 30% taller than ostriches, and could weigh as much as half a ton. Their huge eggs, also about 30% larger than ostrich eggs, fascinated Arab Muslim mariners when they visited the island in the 8th through 13th centuries. They are thought to have been at least partially responsible for the legend of the Roc, a giant bird that features in the stories of Sinbad the Sailor.
Written by Michael Anissimov
