They are two species of about 10 and 20 cm in overall length . This proves that some 55 mya , barely into the early Eocene , early perching birds were recognizably distinct . QM specimens F20688 ( carpometacarpus ) and F24685 ( tibiotarsus ) from Murgon , Queensland are fossil bone fragments clearly recognizable as passeriform ; they represent two species of approximately 10 and 20 cm in overall length and prove that some 55 mya , barely into the Early Eocene , early perching birds were recognizably distinct .