Avian evolution

Article By:

Chiappe, Luis M Department of Vertebrate Paleontology, Natural History of Museum of Los Angeles County, Los Angeles, California.

Last reviewed:2003

DOI:https://doi.org/10.1036/1097-8542.YB031365

The genealogical relationship of birds—members of the class Aves—to other vertebrates has been debated throughout the history of evolutionary biology. These days, despite a few poorly substantiated proposals suggesting that birds may be the descendants of a variety of basal archosaurian reptiles (reptiles that predated the dinosaurs), the overwhelming consensus is that Aves are living representatives of the carnivorous theropod dinosaurs. This hypothesis has its roots in the nineteenth century, but in the last decade it has received a great deal of persuasive paleontological support. Despite disagreement regarding the specific theropod taxon that can be placed closest to birds (candidates include the sickle-clawed dromaeosaurids, parrot-headed oviraptorids, and ostrichlike ornithomimids), studies in areas as disparate as osteology (bones), behavior, oology (eggs), and integument (skin) converge to sustain the origin of birds within the maniraptoriform theropods, no longer leaving any reasonable doubt that extant birds are indeed short-tailed, feathered dinosaurs. In addition, the great amount of fossil information discovered over the last 20 years has revealed that the avian taxa that have evolved since their origin are much more diverse than had been expected.

The content above is only an excerpt.