It is generally agreed that the Neornithes evolved in the Cretaceous Period and that the split between the Palaeognathae and Neognathae , and then the split between Galloanserae ( fowl ) and the other Neognathae , occurred before the Cretaceous-Paleogene extinction event ( the earliest fossil remains confidently referred to the Neornithes come from the possible galliform Austinornis , dated to about 85 mya , though the 130 million year old Hauterivian age Gallornis straeleni may also be a neornithine ) , but there are different opinions about whether the radiation of the remaining neognathes occurred before or after the extinction of the other dinosaurs .
It is generally agreed that the Neornithes evolved in the Cretaceous and that the split between the Palaeognathae and Neognathae , and then the split between fowl and the other Neognathae , occurred before the K\/T extinction event .