Birds have a class all their own called Aves. Within this broad class is a subclass called the Neornithes. This grouping includes the approximately 10,000 species of living birds. Another classification term for these birds is Neoaves, a basal division of birds that includes 95 percent of all living birds. In turn, this grouping is further divided into four suborders based on the palate anatomy of the birds. (There also are some different classification systems for birds, including one that divides the Neornithes only into the Palaeognathae and the Neognathae; for purposes of this discussion, we will use the four suborder classifications.) The four suborders are the Palaeognathae, which are divided into two subgroups, the ratites (such as ostriches, rheas, emus, and other large, flightless birds) and tinamous (such as the South American tinamous); Impennes (penguins); the Odontognathae (fossil birds); and Neognathae (all other living birds, from hummingbirds to plovers).