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an order of extinct toothed birds wide-spread in the Cretaceous period. There were two genera. The birds, known from North America, measure up to 1 m high. Incontrast to birds that lived in the Cenozoic, the Ichthyornitheshad biconcave vertebrae, and their jaws were studded with tinysharp teeth that bent backward and were set in separate sockets The left and right rami of the lower jaw were not joined. TheIchthyornithes had a well-developed sternum with a keel andwings and flew well. They fed on fish.