moa and other species (IMAGE) Harvard University Caption Little bush moa (third from left) are related to the ostrich, rhea, and tinamou. Wing bones are greatly reduced in ostrich and rhea and completely absent in moa. Ostrich, rhea and moa also have sternums with no keel, a hallmark of flightless birds. Credit Wren Lu Usage Restrictions None License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.