neornithine

Neornithes is the clade that encompasses all living birds. This group is characterized by a number of distinct features, including feathers, a beak without teeth, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton. The evolution of birds from theropod dinosaurs is a well-established scientific consensus, with fossil evidence providing a clear lineage.

Within Neornithes, there are two major infraclasses: Palaeognathae and Neognathae. Palaeognathae, often referred to as ratites, include flightless birds such as ostriches, emus, and kiwis. They are distinguished by their flat sternum lacking a keel, which is an adaptation for their terrestrial lifestyle. Neognathae, on the other hand, comprises the vast majority of bird species, including all flying birds and many flightless ones like penguins. Neognathae possess a keeled sternum that provides a large surface area for the attachment of flight muscles.

The diversity of Neornithes is extraordinary, with over 10,000 known species inhabiting virtually every ecosystem on Earth. This diversity is reflected in their varied diets, nesting behaviors, vocalizations, and migratory patterns. Birds play crucial roles in their environments, acting as pollinators, seed dispersers, and predators, contributing significantly to ecological balance. Ongoing research continues to uncover new insights into the evolution, behavior, and conservation of these fascinating animals.