Editing Flightless bird (section)

====Independent evolution of flightlessness in Palaeognathes====
[[Ratite]]s belong to the superorder [[Palaeognathae]], which include the [[Flying and gliding animals|volant]] [[tinamou]], and are believed to have evolved flightlessness independently multiple times within their own group.<ref name=":0" /><ref name=":1" /><ref name="Phillips, M. J. 2010" /><ref name="Mitchell, K. 2014" /> Some birds evolved flightlessness in response to the absence of predators, for example on [[oceanic island]]s. Incongruences between ratite phylogeny and Gondwana geological history indicate the presence of ratites in their current locations is the result of a secondary invasion by flying birds.<ref>{{Cite journal |pmid = 22977150|pmc = 3479725|year = 2012|last1 = Haddrath|first1 = O.|title = Multiple nuclear genes and retroposons support vicariance and dispersal of the palaeognaths, and an Early Cretaceous origin of modern birds|journal = Proceedings. Biological Sciences|volume = 279|issue = 1747|pages = 4617–25|last2 = Baker|first2 = A. J.|doi = 10.1098/rspb.2012.1630}}</ref> It remains possible that the most recent common ancestor of ratites was flightless and the tinamou regained the ability to fly.<ref>{{Cite journal |pmid = 18765814|pmc = 2533212|year = 2008|last1 = Harshman|first1 = J.|title = Phylogenomic evidence for multiple losses of flight in ratite birds|journal = Proceedings of the National Academy of Sciences of the United States of America|volume = 105|issue = 36|pages = 13462–7|last2 = Braun|first2 = E. L.|last3 = Braun|first3 = M. J.|last4 = Huddleston|first4 = C. J.|last5 = Bowie|first5 = R. C.|last6 = Chojnowski|first6 = J. L.|last7 = Hackett|first7 = S. J.|last8 = Han|first8 = K. L.|last9 = Kimball|first9 = R. T.|last10 = Marks|first10 = B. D.|last11 = Miglia|first11 = K. J.|last12 = Moore|first12 = W. S.|last13 = Reddy|first13 = S.|last14 = Sheldon|first14 = F. H.|last15 = Steadman|first15 = D. W.|last16 = Steppan|first16 = S. J.|last17 = Witt|first17 = C. C.|last18 = Yuri|first18 = T.|doi = 10.1073/pnas.0803242105|bibcode = 2008PNAS..10513462H|doi-access = free}}</ref> However, it is believed that the loss of flight is an easier transition for birds than the loss and regain of flight, which has never been documented in avian history.<ref name="Phillips, M. J. 2010"/> Moreover, tinamou nesting within flightless ratites indicates ancestral ratites were volant and multiple losses of flight occurred independently throughout the lineage. This indicates that the distinctive flightless nature of ratites is the result of convergent evolution.<ref name="Smith, J. V. 2012"/>