Temporal range: Eocene-Recent, 55–0Ma
|Striated Pardalote (Pardalotus striatus)|
|Song of a Purple-crowned Fairywren (Malurus coronatus)|
and see text
|Roughly 100 families, around 5,400 species|
A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. A notable feature of passerines is the arrangement of their toes (three pointing forward and one back) which facilitates perching. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders, with over 5,000 identified species. It has roughly twice as many species as the largest of the mammal orders, the Rodentia. It contains more than 110 families, the second most of any order of vertebrates (after the Perciformes).
The names "passerines" and "Passeriformes" are derived from Passer domesticus, the scientific name of the eponymous species (the House Sparrow) and ultimately from the Latin term passer for Passer sparrows and similar small birds.
- 1 Description
- 2 Anatomy
- 3 Eggs and nests
- 4 Origin and evolution
- 5 Systematics and taxonomy
- 6 Taxonomic list of Passeriformes families
- 7 Footnotes
- 8 References
The order is divided into three suborders, Tyranni (suboscines), Passeri (oscines), and the basal Acanthisitti. Oscines have the best control of their syrinx muscles among birds, producing a wide range of songs and other vocalizations (though some of them, such as the crows, do not sound musical to human beings); some such as the lyrebird are accomplished imitators. The Acanthisittids or New Zealand wrens are tiny birds restricted to New Zealand, at least in modern times; they were long placed in Passeri; their taxonomic position is uncertain, although they seem to be a distinct and very ancient group.
Most passerines are smaller than typical members of other avian orders. The heaviest and altogether largest passerines are the Thick-billed Raven and the larger races of Common Raven, each exceeding 1.5 kg (3.3 lb) and 70 cm (28 in). The Superb Lyrebird and some birds-of-paradise, due to very long tails or tail coverts, are longer overall. The smallest passerine is the Short-tailed Pygmy-Tyrant, at 6.5 cm (2.6 in) and 4.2 g (0.15 oz).
The foot of a passerine has three toes directed forward and one toe directed backward, called anisodactyl arrangement. This arrangement enables the passerine birds to perch upon vertical surfaces, such as trees and cliffs. The toes have no webbing or joining, but in some cotingas the second and third toes are united at their basal third. The hind toe joins the leg at the same level as the front toes. In other orders of birds the toe arrangement is different.
The leg arrangement of passerine birds contains a special adaption for perching. A tendon in the rear of the leg running from the underside of the toes to the muscle behind the Tibiotarsus will automatically be pulled and tighten when the leg bends, causing the foot to curl and become stiff when the bird lands on a branch. This enables passerines to sleep while perching without falling off. This is especially useful for passerine birds that develop nocturnal lifestyles. 
Most passerine birds develop twelve tail feathers, although the Superb Lyrebird has sixteen. Certain species of passerines have stiff tail feathers, which help the birds balance themselves when perching upon vertical surfaces. Some passerines, specifically in the family Ploceidae, are well known for their elaborate sexual ornaments, including extremely long tails. A well-known example is the Long-tailed Widowbird.
Eggs and nests
The chicks of passerines are altricial: blind, featherless, and helpless when hatched from their eggs. Hence, the chicks require extensive parental care. Most passerines lay coloured eggs, in contrast with non-passerines, most of whose eggs are white except in some ground-nesting groups such as Charadriiformes and nightjars, where camouflage is necessary, and in some parasitic cuckoos, which match the passerine host's egg.
Clutches vary considerably in size: some larger passerines of Australia such as lyrebirds and scrub-robins lay only a single egg, most smaller passerines in warmer climates lay between two and five, whilst in the higher latitudes of the northern hemisphere hole-nesting species like tits can lay up to a dozen and other species around five or six.
Origin and evolution
The evolutionary history of the passerine families and the relationships among them remained rather mysterious until the late twentieth century. In many cases, passerine families were grouped together on the basis of morphological similarities which, it is now believed, are the result of convergent evolution, not a close genetic relationship. For example, the "wrens" of the northern hemisphere, those of Australia, and those of New Zealand look very similar and behave in similar ways, and yet belong to three far-flung branches of the passerine family tree; they are as unrelated as it is possible to be while remaining Passeriformes.
Much research remains to be done, but advances in molecular biology and improved paleobiogeographical data gradually are revealing a clearer picture of passerine origins and evolution that reconciles molecular affinities, the constraints of morphology and the specifics of the fossil record. It is now thought that the first passerines evolved in Gondwana at some time in the Paleogene, maybe around the Late Paleocene some 60–55 mya. The initial split was between the Tyranni, the songbirds, the Eurylaimides and the New Zealand "wrens", which must have diverged during a short period of time (some million years at most). The Passeriformes apparently evolved out of a fairly close-knit clade of "near passerines" which contains such birds as the Piciformes and Coraciiformes.
A little later, a great radiation of forms took place out of Australia-New Guinea: the Passeri or songbirds. A major branch of the Passeri, "Parvorder Passerida", emerged either as the sister group to the basal lineages and corvoids ("Parvorder Corvida"), or more likely as a subgroup of it, and expanded deep into Eurasia and Africa, where there was a further explosive radiation of new lineages. This eventually led to three major passeridan lineages comprising about 4,000 species, which in addition to the corvoidan clade and numerous minor lineages make up songbird diversity today. There has been extensive biogeographical mixing, with northern forms returning to the south, southern forms moving north, and so on.
Perching bird osteology, especially of the limb bones, is rather diagnostic. However, the early fossil record is poor because the first Passeriformes were apparently on the small side of the present size range, and their delicate bones did not preserve well. Queensland Museum specimens F20688 (carpometacarpus) and F24685 (tibiotarsus) from Murgon, Queensland are fossil bone fragments clearly recognizable as passeriform; they represent two species of approximately 10 and 20 cm in overall length and prove that some 55 mya, barely into the Early Eocene, early perching birds were recognizably distinct.
A quite similar group, the Zygodactylidae (named for their zygodactylous approach to perching) independently arose at much the same time – and possibly from closely related ancestors – in the landmasses bordering the North Atlantic, which at that time was only some two-thirds of its present width.
Until the discovery of the Australian fossils mentioned, Palaeospiza bella from the Priabonian Florissant Fossil Beds (Late Eocene, around 35 mya) was the oldest known passeriform. However, it is now considered a non-passeriform near passerine.
From the Bathans Formation at the Manuherikia River in Otago, New Zealand, MNZ S42815 (a distal right tarsometatarsus of a Tui-sized bird) and several bones of at least one species of Saddleback-sized bird have recently been described. These date from the Early to Middle Miocene (Awamoan to Lillburnian, 19-16 mya).
Modern knowledge about the living passerines' interrelationships (see the list of families below) suggests that the last common ancestor of all living Passeriformes was a small forest bird, probably with a stubby tail and an overall drab coloration, but possibly with marked sexual dimorphism. The latter trait seems to have been lost and re-evolved multiple times in songbird evolution alone, judging from its distribution among the extant lineages. Sexual dichromatism is very rare among the basal lineages of Passerida, and probably their plesiomorphic condition. But among the youngest passerid clade, the Passeroidea, extremely colorful males and drab females are common, if not the rule. On the other hand, among the basalmost Passeri there are a considerable number of strongly dimorphic lineages too, such as the very ancient Menuridae as well as many Meliphagoidea and Corvoidea. Sexual dimorphism is also not uncommon in the Acanthisittidae and prominent in some suboscines such as the Pipridae and Cotingidae.
Early European passerines
In Europe, perching birds are not too uncommon in the fossil record from the Oligocene onwards, but most are too fragmentary for a more definite placement:
- Wieslochia (Early Oligocene of Frauenweiler, Germany)
- Jamna (Early Oligocene of Jamna Dolna, Poland)
- Resoviaornis (Early Oligocene of Wola Rafałowska, Poland)
- Passeriformes gen. et sp. idet. (Early Oligocene of Luberon, France) – suboscine or basal
- Passeriformes gen. et spp. indet. (Late Oligocene of France) – several suboscine and oscine taxa
- Passeriformes gen. et spp. indet. (Middle Miocene of France and Germany) – basal?
- Passeriformes gen. et spp. indet. (Sajóvölgyi Middle Miocene of Mátraszõlõs, Hungary) – at least 2 taxa, possibly 3; at least one probably Oscines
- Passeriformes gen. et sp. indet. (Middle Miocene of Felsõtárkány, Hungary) – oscine?
- Passeriformes gen. et sp. indet. (Late Miocene of Polgárdi, Hungary) – Sylvioidea (Sylviidae? Cettiidae?)
Wieslochia was possibly not a member of any extant suborder. That not only the Passeri expanded much beyond their region of origin is proven by an undetermined broadbill (Eurylaimidae) from the Early Miocene (roughly 20 mya) of Wintershof, Germany, and the indeterminate Late Oligocene suboscine from France listed above. Even very basal Passeriformes might have been common in Europe until the Middle Miocene, some 12 mya. Extant Passeri superfamilies were quite distinct by that time and are known since about 12–13 mya when modern genera were present in the corvoidean and basal songbirds. The modern diversity of Passerida genera is known mostly from the Late Miocene onwards and into the Pliocene (about 10–2 mya). Pleistocene and early Holocene lagerstätten (<1.8 mya) yield numerous extant species, and many yield almost nothing but extant species or their chronospecies and paleosubspecies.
In the Americas, the fossil record is more scant before the Pleistocene, from which several still-existing suboscine families are documented. Apart from the indeterminable MACN-SC-1411 (Pinturas Early/Middle Miocene of Santa Cruz Province, Argentina), an extinct lineage of perching birds has been described from the Late Miocene of California, USA: the Palaeoscinidae with the single genus Paleoscinis. "Palaeostruthus" eurius (Pliocene of Florida) probably belongs to an extant family, most likely passeroidean.
Systematics and taxonomy
Corvida and Passerida were classified as "parvorders" in the suborder Passeri; in accord with the usual taxonomic practice, they would probably be ranked as infraorders. As originally envisioned in the Sibley-Ahlquist taxonomy, they contained, respectively, the large superfamilies Corvoidea and Meliphagoidea as well as minor lineages, and the superfamilies Sylvioidea, Muscicapoidea and Passeroidea.
The arrangement has been found to be overly simplified by more recent research. Since the mid-2000s, literally dozens of studies are being published which try rather successfully to resolve the phylogeny of the passeriform radiation. For example, the Corvida in the traditional sense were a rather arbitrary assemblage of early and/or minor lineages of passeriform birds of Old World origin, generally from the region of Australia, New Zealand, and Wallacea. The Passeri on the other hand can be made monophyletic by moving some families about, but the "clean" three-superfamily-arrangement has turned out to be far more complex and it is uncertain whether future authors will stick to it.
Major "wastebin" families such as the Old World warblers and Old World babblers have turned out to be paraphyletic and are being rearranged. Several taxa turned out to represent highly distinct species-poor lineages and consequently new families had to be established, some of them – like the Stitchbird of New Zealand and the Eurasian Bearded Reedling – monotypic with only one living species. It seems likely that in the Passeri alone, a number of minor lineages will eventually be recognized as distinct superfamilies. For example, the kinglets constitute a single genus with less than 10 species today, but seem to have been among the first perching bird lineages to diverge as the group spread across Eurasia. No particularly close relatives of them have been found among comprehensive studies of the living Passeri, though it is suspected that they might be fairly close to some little-studied tropical Asian groups. Treatment of the nuthatches, wrens, and their closest relatives as a distinct superfamily Certhioidea is increasingly considered justified; the same might eventually apply to the tits and their closest relatives.
This process is still continuing. Therefore, the arrangement as presented here is subject to change. However, it should take precedence over unreferenced conflicting treatments in family, genus and species articles here; see the next section for default sources.
Taxonomic list of Passeriformes families
This list is in taxonomic order, placing related species/groups next to each other. The Passerida subdivisions are updated as needed from the default sequence of the Handbook of the Birds of the World, based on the most modern and comprehensive studies.
Regarding arrangement of families
The families are sorted into a somewhat novel sequence unlike that in older works, where e.g. Corvidae are placed last. This is because so many reallocations have taken place since about 2005 that a definite taxonomy has not been established yet, although the phylogeny is by and large resolved. The present sequence is an attempt to preserve as much of the traditional sequence while giving priority to adequately addressing the phylogenetic relationships between the families.
- Acanthisittidae: New Zealand "wrens"
- Infraorder Eurylaimides – Old World suboscines (or Broad-billed suboscines). Probably a separate suborder.
- Infraorder Tyrannides – New World suboscines
- Superfamily N.N. – "bronchophones"
- Superfamily Furnarioidea – tracheophones
Songbirds or oscines
- Basal Passeri – the most ancient true songbirds, endemic to Australia. Sometimes considered a superfamily "Menuroidea"[verification needed].
- Superfamily Meliphagoidea – mainly insectivores and nectarivores, distribution centered on Australo-Melanesian region extending into surroundings, notably the Pacific.
- Maluridae: fairywrens, emu-wrens and grasswrens
- Dasyornithidae: bristlebirds. Formerly in Acanthizidae.
- Acanthizidae: scrubwrens, thornbills, and gerygones
- Meliphagidae: honeyeaters
- Meliphagoidea incertae sedis
- Superfamily Corvoidea – a highly diverse group of global distribution, but most plentiful in the Australasian region and surroundings. The oldest truly globally successful group of passerines, they include among them what may well be the most intelligent and the most spectacular of the order.
- Callaeidae: New Zealand wattlebirds. Tentatively placed here.
- Notiomystidae: Stitchbird. Tentatively placed here.
- Cnemophilidae: satinbirds. Tentatively placed here.
- Melanocharitidae: berrypeckers and longbills. Tentatively placed here.
- Neosittidae: sittellas
- Vireonidae: vireos
- Campephagidae: cuckoo-shrikes and trillers
- Pachycephalidae: whistlers and allies. Delimitation with regards to several proposed families and subfamilies requires thorough study.
- Oriolidae: orioles and Figbird, Piopio
- Paramythiidae: Tit Berrypecker and Crested Berrypecker. Formerly in Passerida.
- Artamidae: woodswallows, butcherbirds, currawongs and Australian Magpie
- Malaconotidae: puffback shrikes, bush shrikes, tchagras and boubous
- Platysteiridae: wattle-eyes and relatives. Formerly in Passerida. Probably paraphyletic.
- Aegithinidae: ioras
- Pityriaseidae: Bornean Bristlehead. Tentatively placed here.
- Prionopidae: helmetshrikes and woodshrikes
- Vangidae: vangas
- Dicruridae: drongos
- Monarchidae: monarch flycatchers
- Rhipiduridae: fantails
- Paradisaeidae: birds of paradise
- Corcoracidae: White-winged Chough and Apostlebird
- Laniidae: shrikes
- Corvidae: crows, ravens and jays
- Corvoidea incertae sedis
- Vireolanius: shrike-vireos. Usually included in Vireonidae, possibly a monotypic family,
- Erpornis: White-bellied Erpornis. Formerly in Yuhina (Passerida: Timaliidae); possibly a monotypic family, possibly in Vireonidae
- Colluricinclidae: shrike-thrushes. Often included in Pachycephalidae but perhaps recognizable as a subfamily at least.
- Cinclosomatidae: whipbirds and allies. Contains Psophodidae but that might make it paraphyletic. At least some species belong in Pachycephalidae if Falcunculinae are not considered a distinct family.
- Falcunculidae: Shrike-tit and allies. Usually included in Pachycephalidae; might be distinct family or merged in Cinclosomatidae or Psophodidae[verification needed].
- "Pitohuidae": pitohuis. Usually included in Pachycephalidae but seem closer to Oriolidae and best considered a distinct family including Oreoica and possibly other Pachycephalidae sensu lato.
- Melampitta: melampittas. Two very puzzling birds of unclear systematics; the monophyly of the genus was long disputed. Maybe a basal offshoot of the Monarchidae, maybe a family of their own.
- Passeri (mainly "Corvida") incertae sedis
- Possible superfamily "Ptilonorhynchoidea"[verification needed] – bowerbirds and Australian treecreepers. Endemic to Australia-New Guinea. Two very dissimilar families, one smallish and inconspicuous, the other sizeable, usually brightly colored and/or conspicuously vocal, and with extremely unusual mating habits.
- Possible superfamily N.N. – logrunners and pseudo-babblers. Insectivores, endemic to Australia-New Guinea. Mid-sized and rather inconspicuous, wings short and round but tails well-developed. Plumage grey and brown with black and white markings, males and females look alike.
- Petroicidae: Australian robins
- Possible superfamily N.N. – rockfowl and allies. Eat large arthropods and sometimes small vertebrates. Relictual distribution in 3 areas of the Old World tropics. Mid-sized to large songbirds with strong legs, adapted to move long distances on foot across rough ground. Males and females look alike.
- Possible monotypic superfamily Reguloidea – kinglets (Regulidae). Tiny forest-dwelling insectivores, found only in the Northern Hemisphere. Greenish above, whitish below and striking (at close range) head pattern of black and yellow to red stripes. Sexual dimorphism slight.
- Irenidae: fairy-bluebirds. Reguloidea? Basal to/in Passeroidea?
- Chloropseidae: leafbirds. Reguloidea? Basal to/in Passeroidea?
- Possible monotypic superfamily N.N. - hyliotas (Hyliotidae). Recently split from Sylviidae. Basal to/in Passerida? Restricted to the Afrotropics, resemble "Old world warblers" but quite colorful.
- Passerida incertae sedis – Rather basal Passerida, most of which seem to constitute several small but distinct lineages that could be considered superfamilies. Most occur in Asia, Africa and North America.
- Possible superfamily Paroidea – titmice and allies. Might be included in Sylvioidea. Feed mainly on arthropods, seeds and berries. Widely distributed but absent from South America and the Australian region[verification needed]. Smallish round-bodied acrobatic birds, often brightly colored with large patches of yellow, blue, green, black and white. Males and females usually look quite alike.
- Possible superfamily Bombycilloidea – waxwings and allies. Included in Muscicapoidea if Sittoidea/Certhioidea are also included there. Omnivores but strongly prefer juicy fruit and nectar. Laurasian; essentially[verification needed] limited to the Northern Hemisphere. Mid-sized and typically fairly inconspicuous except for their habit of roaming around in noisy flocks. Plumage typically grey-hued and with silk-like texture, but many have a conspicuous black face and/or yellow ornaments; several melanic lineages. Sexual dimorphism slight if any.
- Possible superfamily "Dicaeoidea" – sunbirds and flowerpeckers. Might be included in Passeroidea. Eat mostly nectar, pollen and berries, supplemented with arthropods. Generally restricted to the Old World tropics. Plumage usually extremely colorful at least in males, usually a few contrasting hues (commonly including black and/or white, and usually including red) and in some with metallic sheen. Sexual dimorphism usually pronounced; females in most species greenish above, lighter below.
- Possible monotypic superfamily "Promeropoidea" – sugarbirds (Promeropidae). Might be included in Passeroidea. Living fossils with a nondescript "honeyeater" or "warbler" phenotype, a Capensis relict lineage only found in Africa south of the Equatorial region. Include keystone species for fynbos and some Afromontane forest ecosystems. Sexual dimorphism does not appear pronounced, but includes many little-studied species.
- Superfamily Sylvioidea - "Old World warblers/babblers" and allies. Generally insectivores, sometimes supplemented with berries; distribution centered on the Indo-Pacific region. Few occur in the Australian region and fewer still in the Americas. Usually slender and drab birds, few have pronounced sexual dimorphism.
- Nicatoridae: nicators; have been classed as bulbuls in the past but appear to have no close relatives.
- Panuridae: the Bearded Reedling; formerly classed as a parrotbill but seems to be closest to the larks.
- Alaudidae: larks
- Hirundinidae: swallows and martins
- Pnoepygidae: pygmy wren-babblers; apparently unrelated to other babblers
- Macrosphenidae: African warblers such as longbills[disambiguation needed] and crombecs; a recently proposed family whose composition is still uncertain
- Phylloscopidae: leaf-warblers and allies. Recently split from Sylviidae.
- Aegithalidae: long-tailed tits or bushtits
- Cettiidae: ground-warblers and allies. Recently split from Sylviidae.
- Locustellidae: grass-warblers and allies. Recently split from Sylviidae.
- Donacobiidae: the Black-capped Donacobius; previously classed as a wren but probably closest to the Locustellidae or Bernieridae
- Bernieridae: Malagasy warblers. A newly assembled family.
- Acrocephalidae: marsh- and tree-warblers. Recently split from Sylviidae.
- Pycnonotidae: bulbuls
- Cisticolidae: cisticolas and allies
- Timaliidae: tree babblers
- Pellorneidae: ground babblers
- Leiothrichidae: laughingthrushes and allies
- Sylviidae: Sylvia warblers and allies
- Zosteropidae: white-eyes and allies
- Superfamily Certhioidea – wrens, treecreepers and allies. Sometimes included in Muscicapoidea. Occur in the Americas and Eurasia, though mostly north of the Alpide belt. Distribution and the basal fossil Certhiops indicates the Certhioidea probably originated around the end of the Paleogene somewhere around the North Atlantic. Small, often tiny, tend to be conspicuously plump but nimble; many accomplished climbers. Plumage extremely cryptic or somewhat colorful, in the latter case typically blue-grey at least on the upperside. Sexes look identical or almost so, but may differ strongly in vocalizations.
- Sittidae: nuthatches
- Tichodromadidae: Wallcreeper: Traditionally placed as a subfamily of the nuthatches and more rarely of the treecreepers, no study has been able to verify either placement this far. Thus it is better considered a monotypic family, at least for the time being.
- Certhiidae: treecreepers
- Salpornithidae: spotted creepers. Tentatively placed here; often considered a subfamily of the Certhidae.
- Troglodytidae: wrens
- Polioptilidae: gnatcatchers
- Superfamily Muscicapoidea - "Old World flycatchers", starlings and allies. Mostly insectivores, near-global distribution centered on Old World tropics. One family endemic to Americas. Nearly absent (except introductions) from the Australian region. Usually rather robust for their size, most are quite dark and dull though Sturnidae are commonly iridescent and/or colorful. Sexual dimorphism often absent, sometimes pronounced.
- Cinclidae: dippers
- Muscicapidae: Old World flycatchers and chats. Monophyly needs confirmation.
- Turdidae: thrushes and allies. Monophyly needs confirmation.
- Buphagidae: oxpeckers. Formerly usually included in Sturnidae.
- Sturnidae: starlings and possibly Philippine creepers. Placement of latter in Muscicapoidea seems good, but inclusion in Sturnidae requires confirmation; possibly distinct family Rhabdornithidae.
- Mimidae: mockingbirds and thrashers
- Superfamily Passeroidea - "finches", "New World warblers/blackbirds" and allies. Mostly herbivores including many seed-eaters but some specialized insectivores; near-global distribution centered on Palearctic and Americas. Includes the Nine-primaried oscines (probably a subclade). A very high proportion of colorful and highly sexually dimorphic forms.
- Passeridae: true sparrows
- Prunellidae: accentors
- Motacillidae: wagtails and pipits
- Urocynchramidae: Przewalski's Finch. Recently split from Fringillidae; tentatively placed here.
- Estrildidae: estrildid finches (waxbills, munias, etc.)
- Ploceidae: weavers. Certain members of Ploceidae, such as the Long-tailed Widowbird are well known for their elaborate sexual ornaments.
- Viduidae: indigobirds and whydahs
- Nine-primaried oscines:
- Peucedramidae: Olive Warbler
- Fringillidae: true finches and Hawaiian honeycreepers. Possibly polyphyletic.
- Icteridae: grackles, New World blackbirds, and New World orioles
- Parulidae: New World warblers
- Thraupidae: tanagers and allies, Bananaquit
- Cardinalidae: cardinals
- Emberizidae: buntings and American sparrows
- Mayr, Ernst (1946). "The Number of Species of Birds". The Auk 63 (1): 67. doi:10.2307/4079907.
- Stefoff, Rebecca (2008), "The Bird Class", Marshall Cavendish Benchmark
- Brooke, Michael and Birkhead, Tim (1991) "The Cambridge Encyclopedia of Ornithology", Cambridge University Press ISBN 0521362059.
- Jones, D. (2008). Flight of fancy. Australian Geographic, (89), 18-19.
- The name wren has been applied to other, unrelated birds in Australia and New Zealand. The 27 Australasian "wren" species in the family Maluridae are unrelated, as are the New Zealand wrens in the family Acanthisittidae, the antwrens in the family Thamnophilidae, and the wren-babblers of the family Timaliidae. For the monophyly of the "true wrens", Troglodytidae, see Barker, F. K. (2004). "Monophyly and relationships of wrens (Aves: Troglodytidae): a congruence analysis of heterogeneous mitochondrial and nuclear DNA sequence data". Molecular Phylogenetics and Evolution 31 (2): 486–504. doi:10.1016/j.ympev.2003.08.005. PMID 15062790.
- The context is summarised in Dyke, Gareth J.; Van Tuinen, Marcel (2004). "The evolutionary radiation of modern birds (Neornithes): Reconciling molecules, morphology and the fossil record". Zoological Journal of the Linnean Society 141 (2): 153. doi:10.1111/j.1096-3642.2004.00118.x.
- Ericson, PG; Christidis, L; Cooper, A; Irestedt, M; Jackson, J; Johansson, US; Norman, JA (2002). "A Gondwanan origin of passerine birds supported by DNA sequences of the endemic New Zealand wrens". Proceedings of the Royal Society B 269 (1488): 235–41. doi:10.1098/rspb.2001.1877. PMC 1690883. PMID 11839192.
- Johansson & Ericson (2003);
- See e.g. Boles (1997), Manegold et al. (2004), Mayr & Manegold (2006)
- Boles (1997)
- Worthy et al. (2007)
- The last common ancestor of all songbirds most likely had a decidedly longer tail. See del Hoyo et al. (2003, 2004).
- Specimen SMF Av 504. A flattened right hand of a passerine perhaps 10 cm long overall. If suboscine, perhaps closer to Cotingidae than to Eurylaimides: Roux (2002), Mayr & Manegold (2006)
- Huguenet et al. (2003), Mayr & Manegold (2006)
- Specimens SMF Av 487–496; SMNS 86822, 86825-86826; MNHN SA 1259–1263: tibiotarsus remains of small, possibly basal Passeriformes: Manegold et al. (2004)
- A partial coracoid of a probable Muscicapoidea, possibly Turdidae; distal tibiotarsus and tarsometatarsus of a smallish to mid-sized passerine which may be the same as the preceding; proximal ulna and tarsometatarsus of a Paridae-sized passerine: Gál et al. (1998–1999, 2000)
- A humerus diaphysis piece of a swallow-sized passerine: Hír et al. (2001)
- Hír et al. (2001)
- Manegold et al. (2004)
- Distal right humerus, possibly suboscine: Noriega & Chiappe (1991, 1993)
- The former does not even have recognized subspecies, while the latter is one of the most singular birds alive today. Good photos of a Bearded Reedling are for example here and here.
- del Hoyo et al. (2003–)
- Lovette & Bermingham (2000), Cibois et al. (2001), Barker et al. (2002, 2004), Ericson & Johansson (2003), Beresford et al. (2005), Alström et al. (2006), Jønsson & Fjeldså (2006)
- Lovette, I.J. (2008). "Convergent evolution: Raising a family from the dead". Current biology : CB 18 (24): R1132–4. doi:10.1016/j.cub.2008.11.006. PMID 19108768.
- Fleischer R.C., James H.F., and Olson S.L. (2008). "Convergent evolution of Hawaiian and Australo-Pacific honeyeaters from distant songbird ancestors". Current biology : CB 18 (24): 1927–31. doi:10.1016/j.cub.2008.10.051. PMID 19084408.
- Gill, F., Wright, M. & Donsker, D. (2008). IOC World Bird Names (version 1.6). Available at http://www.worldbirdnames.org/
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- Alström, Per; Ericson, Per G.P.; Olsson, Urban & Sundberg, Per (2006). "Phylogeny and classification of the avian superfamily Sylvioidea". Mol. Phylogenet. Evol. 38 (2): 381–397. doi:10.1016/j.ympev.2005.05.015. PMID 16054402.
- Barker, F. Keith; Barrowclough, George F. & Groth, Jeff G. (2002). "A phylogenetic hypothesis for passerine birds: taxonomic and biogeographic implications of an analysis of nuclear DNA sequence data". Proceedings of the Royal Society B 269 (1488): 295–308. doi:10.1098/rspb.2001.1883. PMC 1690884. PMID 11839199.
- Barker, F. Keith; Cibois, Alice; Schikler, Peter A.; Feinstein, Julie & Cracraft, Joel (2004). "Phylogeny and diversification of the largest avian radiation". PNAS 101 (30): 11040–11045. doi:10.1073/pnas.0401892101. PMC 503738. PMID 15263073. Supporting information
- Beresford, P.; Barker, F.K.; Ryan, P.G. & Crowe, T.M. (2005). "African endemics span the tree of songbirds (Passeri): molecular systematics of several evolutionary 'enigmas'". Proceedings of the Royal Society B 272 (1565): 849–858. doi:10.1098/rspb.2004.2997. PMC 1599865. PMID 15888418. Electronic appendix
- Boles, Walter E. (1997). "Fossil Songbirds (Passeriformes) from the Early Eocene of Australia". Emu 97 (1): 43–50. doi:10.1071/MU97004.
- Cibois, Alice; Slikas, Beth; Schulenberg, Thomas S. & Pasquet, Eric (2001). "An endemic radiation of Malagasy songbirds is revealed by mitochondrial DNA sequence data". Evolution 55 (6): 1198–1206. doi:10.1554/0014-3820(2001)055[1198:AEROMS]2.0.CO;2.
- del Hoyo, J.; Elliot, A. & Christie, D. (eds.) (2003): Handbook of the Birds of the World (Vol. 8: Broadbills to Tapaculos). Lynx Edicions. ISBN 84-87334-50-4
- del Hoyo, J.; Elliot, A. & Christie, D. (eds.) (2004): Handbook of the Birds of the World (Vol. 9: Cotingas to Pipits and Wagtails. Lynx Edicions). ISBN 84-87334-69-5
- del Hoyo, J.; Elliot, A. & Christie, D. (eds.) (2005): Handbook of the Birds of the World (Vol. 10: Cuckoo-Shrikes to Thrushes. Lynx Edicions). ISBN 84-87334-72-5
- del Hoyo, J.; Elliot, A. & Christie, D. (eds.) (2006): Handbook of the Birds of the World (Vol. 11: Old World Flycatchers to Old World Warblers). Lynx Edicions. ISBN 84-96553-06-X
- del Hoyo, J.; Elliot, A. & Christie, D. (eds.) (2007): Handbook of the Birds of the World (Vol. 12: Picathartes to Tits and Chickadees). Lynx Edicions. ISBN 978-84-96553-42-2
- Dickinson, E.C. (ed.) (2003): The Howard and Moore complete checklist of the birds of the World (3rd edition). Christopher Helm, London. ISBN 0-7136-6536-X
- Ericson, Per G.P. & Johansson, Ulf S. (2003). "Phylogeny of Passerida (Aves: Passeriformes) based on nuclear and mitochondrial sequence data". Mol. Phylogenet. Evol. 29 (1): 126–138. doi:10.1016/S1055-7903(03)00067-8.
- Gál, Erika; Hír, János; Kessler, Eugén & Kókay, József (1998–99). "Középsõ-miocén õsmaradványok, a Mátraszõlõs, Rákóczi-kápolna alatti útbevágásból. I. A Mátraszõlõs 1. lelõhely" [Middle Miocene fossils from the sections at the Rákóczi chapel at Mátraszőlős. Locality Mátraszõlõs I.]. Folia Historico Naturalia Musei Matraensis 23: 33–78.
- Gál, Erika; Hír, János; Kessler, Eugén, Kókay, József & Márton, Venczel (2000). "Középsõ-miocén õsmaradványok a Mátraszõlõs, Rákóczi-kápolna alatti útbevágásból II. A Mátraszõlõs 2. lelõhely" [Middle Miocene fossils from the section of the road at the Rákóczi Chapel, Mátraszõlõs. II. Locality Mátraszõlõs 2]. Folia Historico Naturalia Musei Matraensis 24: 39–75.
- Hír, János; Kókay, József; Venczel, Márton; Gál, Erika & GKessler, Eugén (2001). "Elõzetes beszámoló a felsõtárkányi "Güdör-kert" n. õslénytani lelõhelykomplex újravizsgálatáról" [A preliminary report on the revised investigation of the paleontological locality-complex "Güdör-kert" at Felsõtárkány, Northern Hungary)]. Folia Historico Naturalia Musei Matraensis 25: 41–64.
- Hugueney, Marguerite; Berthet, Didier; Bodergat, Anne-Marie; Escuillié, François; Mourer-Chauviré, Cécile & Wattinne, Aurélia (2003). "La limite Oligocène-Miocène en Limagne: changements fauniques chez les mammifères, oiseaux et ostracodes des différents niveaux de Billy-Créchy (Allier, France)" [The Oligocene-Miocene boundary in Limagne: faunal changes in the mammals, birds and ostracods from the different levels of Billy-Créchy (Allier, France)]. Geobios 36 (6): 719–731. doi:10.1016/j.geobios.2003.01.002.
- Johansson, Ulf S. & Ericson, Per G.P. (2003). "Molecular support for a sister group relationship between Pici and Galbulae (Piciformes sensu Wetmore 1960)". Journal of Avian Biology 34 (2): 185–197. doi:10.1034/j.1600-048X.2003.03103.x.
- Jønsson, Knud A. & Fjeldså, Jon (2006). "A phylogenetic supertree of oscine passerine birds (Aves: Passeri)". Zool. Scripta 35 (2): 149–186. doi:10.1111/j.1463-6409.2006.00221.x.
- Lovette, Irby J.& Bermingham, Eldredge (2000). "c-mos Variation in Songbirds: Molecular Evolution, Phylogenetic Implications, and Comparisons with Mitochondrial Differentiation". Molecular Biology and Evolution 17 (10): 1569–1577. doi:10.1093/oxfordjournals.molbev.a026255.
- Mayr, Gerald & Manegold, Albrecht (2006). "A Small Suboscine-like Passeriform Bird from the Early Oligocene of France". Condor 108 (3): 717–720. doi:10.1650/0010-5422(2006)108[717:ASSPBF]2.0.CO;2.
- Manegold, Albrecht; Mayr, Gerald & Mourer-Chauviré, Cécile (2004). "Miocene Songbirds and the Composition of the European Passeriform Avifauna". Auk 121 (4): 1155–1160. doi:10.1642/0004-8038(2004)121[1155:MSATCO]2.0.CO;2.
- Noriega, Jorge I. & Chiappe, Luis M. (1991). "El más antiguo Passeriformes de America del Sur. Presentation at VIII Journadas Argentinas de Paleontologia de Vertebrados" [The most ancient passerine from South America]. Ameghiniana 28 (3–4): 410.
- Noriega, Jorge I. & Chiappe, Luis M. (1993). "An Early Miocene Passeriform from Argentina". Auk 110 (4): 936–938. doi:10.2307/4088653.
- Roux, T. (2002). "Deux fossiles d'oiseaux de l'Oligocène inférieur du Luberon" [Two bird fossils from the Lower Oligocene of Luberon]. Courrier Scientifique du Parc Naturel Régional du Luberon 6: 38–57.
- Worthy, Trevor H.; Tennyson, A.J.D.; Jones, C.; McNamara, J.A. & Douglas, B.J. (2007). "Miocene waterfowl and other birds from central Otago, New Zealand". Journal of Systematic Palaeontology 5 (1): 1–39. doi:10.1017/S1477201906001957.