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Modern Birds

David P. Mindell and Joseph W. Brown
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 American Black Duck
taxon links [up-->]Palaeognathae [up-->]Galloanserae [up-->]Neoaves [down<--]Aves Interpreting the tree
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This tree diagram shows the relationships between several groups of organisms.

The root of the current tree connects the organisms featured in this tree to their containing group and the rest of the Tree of Life. The basal branching point in the tree represents the ancestor of the other groups in the tree. This ancestor diversified over time into several descendent subgroups, which are represented as internal nodes and terminal taxa to the right.

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You can click on the root to travel down the Tree of Life all the way to the root of all Life, and you can click on the names of descendent subgroups to travel up the Tree of Life all the way to individual species.

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Neornithes includes all extant birds.  The earliest divergence within Neornithes is between Paleognathae (ratites and tinamous) and Neognathae which includes the two primary taxa Galloanserae and Neoaves (see Groth and Barrowclough 1999, Garcia-Moreno et al. 2003, Cracraft et al. 2004, Edwards et al. 2005)

See references list below for more publications on avian systematics.

Containing group: Aves


Extant birds include about 9000 recognized species, with representatives inhabiting all the major biogeographic regions of the world. Examples of bird groups and their native locales include: loons, auks and buntings in the Holarctic; rheas, motmots and toucans in the Neotropics; ostriches, guineafowl and woodhoopoes in Africa south of the Sahara; pheasants, pittas and babblers in Southeast Asia and northern Indonesia; and emus, cockatoos and owlet-frogmouths from Australia and New Guinea.

Whether modern birds are most closely related to dinosaurs or crocodylian ancestors is a point of current debate. The orders of extant birds appear to have arisen close to each other in time, although their age is uncertain, having been estimated to be about 60 million years old or over 90 million years old based on morphology and fossils (see Feduccia, 1996) and molecular data (Sibley and Ahlquist, 1990; Hedges et al., 1996), respectively.


Birds are unique in having feathers, which enable flight, provide insulation, and are used in visual communication. Modified feathers aid in swimming, sound production, protection via camouflage, water repellence, water transport, tactile sensation, hearing, and support of the body (Stettenheim, 1976). Birds are also warm-blooded, have distinctive bills, produce external eggs, and demonstrate complex parental and reproductive behaviors. Features shared with other reptiles, but not with mammals, include nucleated red blood cells, a single middle ear bone, and a single occipital condyle on the back of the skull. Adaptations for flight include fusion and reinforcement of lightweight bones and presence of a keeled sternum, which supports flight muscles. Birds have highly developed color vision, use vocalizations to mediate social interactions, and are able to detect and react to magnetism (see Gill, 1990).


Classifications of birds following the traditional sequence of orders beginning, approximately, with Struthioniformes (ratites), Procellariformes (albatrosses, petrels), Sphenisciformes (penguins), and Gaviiformes (loons), and ending with Piciformes (woodpeckers) and Passeriformes (perching birds), as found in most field guides and checklists (e.g. Peters 1931-1951), are weakly connected to phylogenetic hypotheses, and tell as much about the history of ornithology as about the history of birds. A recent and revised classification of modern birds (Sibley and Monroe, 1990) reflects phylogenetic hypotheses, with sister groups being assigned coordinate ranks (following Hennig, 1966). However, while the approach is modern, this particular implementation rests on the problematic assumption that melting temperatures for hybridized DNA fragments from pairs of species can be extrapolated to accurately reflect divergence times.

Other Names for Neornithes


Braun, E. L. and R. T. Kimball. 2002. Examining basal avian divergences with mitochondrial sequences: model complexity, taxon sampling, and seqeunce length. Syst. Biol. 51:614-625.

Christidis, L. and W. Boles. 2008. Systematics and Taxonomy of Australian Birds. CSIRO Publishing, Collingwood, Australia.

Chubb, A. L. 2004. New nuclear evidence for the oldest divergence among neognath birds: the phylogenetic utility of ZENK. Molecular Phylogenetics and Evolution 30:140-151.

Cooper, A. and D. Penny. 1997. Mass survival of birds across the Cretaceous-Tertiary boundary: Molecular evidence. Science 275:1109-1113.

Cracraft, J. 1981. Toward a phylogenetic classification of birds of the world (class Aves). Auk 98: 681-714.

Cracraft, J. 1988. The major clades of birds. In The Phylogeny and Classification of the Tetrapods. (M. J. Benton, ed.), Systematics Assoc. Special Vol. No. 35A, pp. 333-355. Clarendon Press, Oxford.

Cracraft, J. 2001. Avian evolution, Gondwana biogeography and the Cretaceous-Tertiary mass extinction event. Proc. Roy. Soc. Lond. 268B:459-469.

Cracraft, J. and J. Clarke. 2001. The basal clades of modern birds. Pp. 143-156 in New perspectives on the origin and early evolution of birds (J. Gauthier and L. F. Gall, eds.). Peabody Museum of Natural History, Yale University, New Haven, CT.

Cracraft, J., F. Keith Barker, M. J. Braun, J. Harshman, G. Dyke, J. Feinstein, S. Stanley, A. Cibois, P. Schikler, P. Beresford, J. García-Moreno, M. D. Sorenson, T. Yuri, and D. P. Mindell. 2004. Phylogenetic Relationships Among Modern Birds (Neornithes): Toward an Avian Tree of Life. Pp 468-489 in Cracraft, J. and M. J. Donoghue (eds.), Assembling the Tree of Life. Oxford University Press, New York.

Cracraft, J., and D. P. Mindell. 1989. The early history of modern birds: a comparison of molecular and morphological evidence. In The Hierarchy of Life. (B. Fernholm, K. Bremer and H. Jörnvall, eds.), Proc. of Nobel Symposia, pp. 389-403. Elsevier Science Publishers, Amsterdam.

Dyke GJ, Van Tuinen M. 2004. The evolutionary radiation of modern birds (Neornithes): reconciling molecules, morphology and the fossil record. Zool. J. Linn. Soc. 141: 153-177.

Edwards, S. V., B. Fertil, A. Giron, and P. J. Deschavanne. 2002. A genomic schism in birds revealed by phylogenetic analysis of DNA strings. Syst. Biol. 51:599-613.

Edwards, S. V., W. B. Jennings and A. M. Shedlock. 2005. Phylogenetics of modern birds in the era of genomics. Proc. R. Soc. B 272:979–992.

Fain, M. G. and P. Houde. 2004. Parallel radiations in the primary clades of birds. Evolution 58:2558-2573.

Feduccia, A. 1999. The Origin and Evolution of Birds. 2nd edition. Yale University Press: New Haven.

García-Moreno, J. and D. P. Mindell. 2000. Using homologous genes on opposite sex chromosomes (gametologs) in phylogenetic analysis: a case study with avian CHD. Molecular Biology and Evolution 17:1826-1832.

García-Moreno, J., M. D. Sorenson and D. P. Mindell. 2003. Congruent avian phylogenies inferred from mitochondrial and nuclear DNA sequences. Journal of Molecular Evolution 57:27-37.

Gill, F. B. 1990. Ornithology. W. H. Freeman and Co., New York.

Gill, F. and M. Wright. 2006. Birds of the World: Recommended English Names. Princeton NJ: Princeton University Press.

Groth, J. G. and G. F. Barrowclough. 1999. Basal divergences in birds and the phylogenetic utility of the nuclear RAG-1 gene. Mol. Phylog. Evol. 12: 115-123.

Härlid, A. and U. Arnason. 1999. Analyses of mitochondrial DNA nest ratite birds within the Neognathae: supporting a neotenous origin of ratite morphological characters. Proc. Roy. Soc. London 266B: 305-309.

Harrison GL, McLenachan PA, Phillips MJ, Slack KE, Cooper A, Penny D. 2004. Four new avian mitochondrial genomes help get to basic evolutionary questions in the late Cretaceous. Mol.Phylogenet. Evol. 21:974-983.

Hedges, S. B., Parker, P. H., Sibley, C. G., and Kumar, S. 1996. Continental breakup and the ordinal diversification of birds and mammals. Nature 381: 226-229.

Hennig, W. 1966. Phylogenetic Systematics. Univ. of Illinois Press, Urbana.

Johnson, K. P. 2001. Taxon sampling and the phylogenetic position of Passeriformes: evidence from 916 avian cytochrome b sequences. Syst. Zool. 50:128-136.

Lee, K., J. Feinstein, and J. Cracraft. 1997. Phylogenetic relationships of the ratite birds: resolving conflicts between molecular and morphological data sets. Pp. 173-211 in Avian Molecular Evolution and Systematics (D. P. Mindell, ed.). Academic Press, New York.

Livezey, B. C. and R. L. Zusi. 2001. Higher-order phylogenetics of modern Aves based on comparative anatomy. Netherlands J. Zool. 51:179-205.

Livezey, B. C. and R. L. Zusi. 2007. Higher-order phylogeny of modern birds (Theropoda, Aves : Neornithes) based on comparative anatomy. II. Analysis and discussion. Zoological Journal of the Linnean Society 149(1):1-95.

Mayr, E., and Cottrell, G. W. 1979. Revision of the Work of J. L. Peters: Check-list of Birds of the World, Vol. 1. Mus. of Comp. Zool., Cambridge.

Mayr, G. 2005. The Paleogene fossil record of birds in Europe. Biological Reviews 80(4):515-542.

Mayr, G. 2008. Avian higher-level phylogeny: well-supported clades and what we can learn from a phylogenetic analysis of 2954 morphological characters. Journal of Zoological Systematics and Evolutionary Research 46(1):63–72.

Mayr G, Clarke J. 2003. The deep divergences of neornithine birds: a phylogenetic analysis of morphological characters. Cladistics 19:527-553.

Mindell, D. P. (ed.). 1997. Avian molecular evolution and systematics. Academic Press: San Diego.

Mindell, D. P., M. D. Sorenson, D. E. Dimcheff, M. Hasegawa, J. C. Ast, and T. Yuri. 1999. Interordinal relationships of birds and other reptiles based on whole mitochondrial genomes. Syst. Biol. 48: 138-152.

Mindell, D. P., M. D. Sorenson, C. J. Huddleston, H. C. Miranda, Jr., A. Knight, S. J. Sawchuk, and T. Yuri. 1997. Phylogenetic relationships among and within select avian orders based on mitochondrial DNA. Pp. 213-247 in Avian Molecular Evolution and Systematics (D. P. Mindell, ed.). Academic Press: San Diego.

Olson, S. L. 1985. The fossil record of birds. In Avian Biology (D. S. Farner, J. R. King, and K. C. Parkes, eds.), Vol. 8, pp. 79-238. Academic Press, New York.

Paton, T., O. Haddrath, and A. J. Baker. 2002. Complete mitochondrial DNA genome sequences show that modern birds are not descended from transitional shorebirds. Proc. Roy. Soc. Lond. 269B:839-846.

Peters, J. L. 1931-1951. Check-list of Birds of the World, Vols. 1-7. Mus. of Comp. Zool., Cambridge.

Poe S, Chubb AL. 2004. Birds in a bush: Five genes indicate explosive evolution of avian orders. Evolution 58:404-415.

Rasmussen, P. C. and J. C. Anderton. 2005. Birds of South Asia: The Ripley Guide. Lynx Edicions, Barcelona.

Sheldon, F. H. and Bledsoe, A. H. 1993. Avian molecular systematics 1970s to 1990s. Annu. Rev. Ecol. Syst. 24: 243-278.

Sibley, C. G. 1994. On the phylogeny and classification of living birds. J. Avian Biol. 25: 87-92

Sibley, C. G. and Ahlquist, J. E. 1990. Phylogeny and classification of birds: a study in molecular evolution. Yale University Press, New Haven.

Sibley, C. G., and B. L. Monroe, Jr. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven.

Slack, K.E. , F. Delsuc, P.A. McLenachan, U. Arnason and D. Penny. 2007. Resolving the root of the avian mitogenomic tree by breaking up long branches. Mol. Phylogen. Evol. 42:1–13.

Slack, K.E., A. Janke, D. Penny, and U. Arnason. 2003. Two new avian mitochondrial genomes (penguin and goose) and a summary of bird and reptile mitogenomic features. Gene 302:43-52.

Stanley, S. E. and J. Cracraft. 2002. Higher-level systematic analysis of birds: current problems and possible solutions. Pp. 31-43 in Molecular Systematics and Evolution: Theory and Practice (R. DeSalle, G. Giribet, and W. Wheeler, eds.). Birkhäuser Verlag, Basel.

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Waddell, P. J., Y. Cao, M. Hasegawa, and D. P. Mindell. 1999. Assessing the Cretaceous superordinal divergence times within birds and placental mammals using whole mitochondrial protein sequences and an extended statistical framework. Systematic Biology 48:119-137.

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Information on the Internet

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Media Collections

Title Illustrations
Click on an image to view larger version & data in a new window
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Scientific Name Rhea americana
Location Brazil
Comments Greater Rhea
Creator Dr. Lloyd Glenn Ingles
Specimen Condition Live Specimen
Source Collection CalPhotos
Copyright © 2001 California Academy of Sciences
American Black Duck
Scientific Name Anas rubripes
Comments American Black Duck
Creator Maslowski Photo
Specimen Condition Live Specimen
Behavior flying
Source Collection U.S. Fish and Wildlife Service Online Digital Media Library
Scientific Name Heliodoxa jacula
Location Monteverde, Costa Rica
Comments Green-crowned Brilliant, a neotropical hummingbird
Specimen Condition Live Specimen
Sex Male
Copyright © Greg and Marybeth Dimijian
About This Page

David P. Mindell
California Academy of Sciences, San Francisco, California, USA

Joseph W. Brown
University of Michigan Museum of Zoology, Ann Arbor, Michigan, USA

Page: Tree of Life Neornithes. Modern Birds. Authored by David P. Mindell and Joseph W. Brown. The TEXT of this page is licensed under the Creative Commons Attribution-NonCommercial License - Version 3.0. Note that images and other media featured on this page are each governed by their own license, and they may or may not be available for reuse. Click on an image or a media link to access the media data window, which provides the relevant licensing information. For the general terms and conditions of ToL material reuse and redistribution, please see the Tree of Life Copyright Policies.

Citing this page:

Mindell, David P. and Joseph W. Brown. 2005. Neornithes. Modern Birds. Version 14 December 2005 (under construction). http://tolweb.org/Neornithes/15834/2005.12.14 in The Tree of Life Web Project, http://tolweb.org/

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For a more detailed explanation of the different ToL page types, have a look at the Structure of the Tree of Life page.

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