Mononykus
               

                                                                     Mononykus fossils have been found from the 
                                                                     Late Cretaceous sediments in Mongolia.  This
                                                                     fossil has recently been described as a primitive
                                                                     flightless bird.  The forelimbs are very short and
                                                                     possess a single claw not typical of birds.
                                                                     The avian features Mononykus does exhibit include
                                                                     a keeled sternum and a reduction of the lower
                                                                     end of the fibula (Chatterjee 1999).  
                                                                     Picture from Nakasato dinosaur Center