Ostriches are flightless birds native to Africa. A flightless extinct quail is also known. The Hesperornithiformes were flightless, marine diving birds that swam like grebes. Some flightless birds grew larger than humans. He also recognized that the ratites were secondarily flightless. The ostriches are a family, Struthionidae, of flightless birds. Ostriches have co-existed with another lineage of flightless didactyl birds, the eogruids. This indicates that the distinctive flightless nature of ratites is the result of convergent evolution. Troodontids had unusually large brains among dinosaurs, comparable to those of living flightless birds. Seasonal cold water has shaped the breeding strategy of flightless cormorants. This allowed the evolution of a number of flightless birds and large reptile species. This family of flightless ratite birds is represented by two living species in Australia. This was fitting with the rhea being a flightless ground bird. The wings were only long, rendering the bird flightless. Australian species range from the tiny weebill to the huge, flightless emu.