There are three extinct groups, the Lithornithiformes, the Dinornithiformes ( moas ) and the Aepyornithiformes ( elephant birds ), that are undisputed members of Palaeognathae.
12.
However, she does find evidence that the Neognathae and, therefore, also the Palaeognathae had diverged no later than the Early Campanian age of the Cretaceous period.
13.
Some sources state that ratites include all the flightless birds of the Palaeognathae; This implies that flightlessness is a trait that evolved independently multiple times in different ratite lineages.
14.
Some studies recover them as a paraphyletic assemblage leading to modern paleognaths, but more recent examinations group them in a single, natural group basal to the rest of Palaeognathae.
15.
Other authors questioned the monophyly of the Palaeognathae on various grounds, suggesting that they could be a hodgepodge of unrelated birds that have come to be grouped together because they are coincidentally flightless.
16.
This study concluded that there were at least three events of flightlessness that produced the different ratite orders, that the similarities between the ratite orders are partly due to convergent evolution, and that the Palaeognathae are monophyletic, but the ratites are not.
17.
The major clades of birds that have UVS vision are Palaeognathae ( ratites and tinamous ), Charadriiformes ( shorebirds, gulls, and alcids ), Trogoniformes ( trogons ), Psittaciformes ( parrots ), and Passeriformes ( perching birds, representing more than half of all avian species ).
18.
They differ from the Palaeognathae in features like the structure of their jawbones . " Neognathae " means " new jaws ", but it seems that the supposedly " more ancient " paleognath jaws are among the few apomorphic ( more derived ) features of this group as compared to the neognaths.
19.
All modern birds lie within the crown group Aves ( alternately Neornithes ), which has two subdivisions : the Palaeognathae, which includes the flightless ratites ( such as the ostriches ) and the weak-flying tinamous, and the extremely diverse Neognathae, containing all other birds . although Livezey and Zusi assigned them " cohort " rank . to 10, 050.
