Containing all modern birds, the subclass Neornithes is, due to the discovery of Vegavis, now known to have evolved into some basic lineages by the end of the Cretaceous and is split into two superorders, the Palaeognathae and Neognathae. The paleognaths include the tinamous of Central and South America and the ratites. The basal divergence from the remaining Neognathes was that of the Galloanserae, the superorder containing the Anseriformes (ducks, geese, swans and screamers) and the Galliformes (the pheasants, grouse, and their allies, together with the mound builders and the guans and their allies). The dates for the splits are much debated by scientists. It is agreed that the Neornithes evolved in the Cretaceous, and that the split between the Galloanseri from other Neognathes occurred before the K–T extinction event, but there are different opinions about whether the radiation of the remaining Neognathes occurred before or after the extinction of the other dinosaurs. This disagreement is in part caused by a divergence in the evidence; molecular dating suggests a Cretaceous radiation, while fossil evidence supports a Tertiary radiation. Attempts to reconcile the molecular and fossil evidence have proved controversial.
May I borrow your hat, please!
The classification of birds is a contentious issue. Sibley and Ahlquist's Phylogeny and Classification of Birds (1990) is a landmark work on the classification of birds, although it is frequently debated and constantly revised. Most evidence seems to suggest that the assignment of orders is accurate, but scientists disagree about the relationships between the orders themselves; evidence from modern bird anatomy, fossils and DNA have all been brought to bear on the problem, but no strong consensus has emerged. More recently, new fossil and molecular evidence is providing an increasingly clear picture of the evolution of modern bird orders.
May I borrow your hat, please!The classification of birds is a contentious issue. Sibley and Ahlquist's Phylogeny and Classification of Birds (1990) is a landmark work on the classification of birds, although it is frequently debated and constantly revised. Most evidence seems to suggest that the assignment of orders is accurate, but scientists disagree about the relationships between the orders themselves; evidence from modern bird anatomy, fossils and DNA have all been brought to bear on the problem, but no strong consensus has emerged. More recently, new fossil and molecular evidence is providing an increasingly clear picture of the evolution of modern bird orders.
I have something wrong with my neck.
How smooth your feather is!
You look ugly when you are mad.
Ducks exploit a variety of food sources such as grasses, aquatic plants, fish, insects, small amphibians, worms, and small molluscs.
Diving ducks and sea ducks forage deep underwater. To be able to submerge more easily, the diving ducks are heavier than dabbling ducks, and therefore have more difficulty taking off to fly.
Dabbling ducks feed on the surface of water or on land, or as deep as they can reach by up-ending without completely submerging. Along the edge of the beak there is a comb-like structure called a pecten. This strains the water squirting from the side of the beak and traps any food. The pecten is also used to preen feathers.
A few specialized species such as the mergansers are adapted to catch and swallow large fish.
The others have the characteristic wide flat beak designed for dredging-type jobs such as pulling up waterweed, pulling worms and small molluscs out of mud, searching for insect larvae, and bulk jobs such as dredging out, holding, turning headfirst, and swallowing a squirming frog. To avoid injury when digging into sediment it has no cere. but the nostrils come out through hard horn.
Diving ducks and sea ducks forage deep underwater. To be able to submerge more easily, the diving ducks are heavier than dabbling ducks, and therefore have more difficulty taking off to fly.
Dabbling ducks feed on the surface of water or on land, or as deep as they can reach by up-ending without completely submerging. Along the edge of the beak there is a comb-like structure called a pecten. This strains the water squirting from the side of the beak and traps any food. The pecten is also used to preen feathers.
A few specialized species such as the mergansers are adapted to catch and swallow large fish.
The others have the characteristic wide flat beak designed for dredging-type jobs such as pulling up waterweed, pulling worms and small molluscs out of mud, searching for insect larvae, and bulk jobs such as dredging out, holding, turning headfirst, and swallowing a squirming frog. To avoid injury when digging into sediment it has no cere. but the nostrils come out through hard horn.
Excuse me, Sir! Give us time to cross this road.
