The brain of a rock pigeon entire from above (top left), entire from below (top right), entire from the lateral left (middle left), vertical-longitunal section (middle right) and horizontal longitudinal sections with increasing depth on each side left to right (bottom two diagrams). Major regions of the brain shown are the cerebral hemispheres (large, paired, round, grey structures), pineal body (red structure between cerebral hemispheres from above), optic lobes (yellow and round, beneath and posterior to cerebral hemispheres), cerebellum (folded structure, central and posterior), and medulla oblongata (gold, paired central structures at very posterior).
Skeletal structure from fossil remains of a flightless, wingless, diving bird of the late Cretaceous. Reduced wings may have been used for steering and the powerful hind legs were closely associated with the body trunk. This makes the probability of them standing erect highly unlikely however this would have provided powerful locomotion when submerged. Hesperornis sp. also had toothed beak which historically provided a strong link between birds and dinosaurs (raptors).