Birds Cuddling

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 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.
Modern bird orders: Classification
This is a list of the taxonomic orders in the subclass Neornithes, or modern birds. This list uses the traditional classification (the so-called Clements order), revised by the Sibley-Monroe classification. The list of birds gives a more detailed summary of the orders, including families.