70-504: Many, see text Wagtails are a group of passerine birds that form the genus Motacilla in the family Motacillidae . The common name and genus name are derived from their characteristic tail pumping behaviour. Together with the pipits and longclaws they form the family Motacillidae . The forest wagtail belongs to the monotypic genus Dendronanthus which is closely related to Motacilla and sometimes included therein. The willie wagtail ( Rhipidura leucophrys ) of Australia
140-511: 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). In Europe, perching birds are not too uncommon in the fossil record from the Oligocene onward, belonging to several lineages: That suboscines expanded much beyond their region of origin
210-471: A black breast-band. The remaining five species are highly variable morphologically and their relationships with each other and with the two clades have not yet been satisfactorily explained. The origin of the genus appears to be in the general area of Eastern Siberia /Mongolia. Wagtails spread rapidly across Eurasia and dispersed to Africa in the Zanclean (Early Pliocene ) where the sub-Saharan lineage
280-470: A clearer picture of passerine origins and evolution that reconciles molecular affinities, the constraints of morphology, and the specifics of the fossil record. The first passerines are now thought to have evolved in the Southern Hemisphere in the late Paleocene or early Eocene , around 50 million years ago. The initial diversification of passerines coincides with the separation of
350-483: A distinct super-family Certhioidea . This list is in taxonomic order, placing related families next to one another. The families listed are those recognised by the International Ornithologists' Union (IOC). The order and the division into infraorders, parvorders, and superfamilies follows the phylogenetic analysis published by Carl Oliveros and colleagues in 2019. The relationships between
420-469: A dozen and other species around five or six. The family Viduidae do not build their own nests, instead, they lay eggs in other birds' nests. The Passeriformes contain several groups of brood parasites such as the viduas , cuckoo-finches , and the cowbirds . The evolutionary history of the passerine families and the relationships among them remained rather mysterious until the late 20th century. In many cases, passerine families were grouped together on
490-542: A green or blue ground colour, while protoporphyrin IX produces reds and browns as a ground colour or as spotting. Non-passerines typically have white eggs, except in some ground-nesting groups such as the Charadriiformes , sandgrouse and nightjars , where camouflage is necessary, and some parasitic cuckoos which have to match the passerine host's egg. Most passerines, in contrast, lay coloured eggs, even if there
560-436: A longer fetal development. Comparatively anatomically simple animals will be able to go through the full development and leave the egg in a form reminiscent of the adult animal. This is the situation found in hagfish and some snails . Animals with smaller size eggs or more advanced anatomy will still have a distinct larval stage, though the larva will be basically similar to the adult animal, as in lampreys , coelacanth and
630-403: A naked egg cell. Mesolecithal eggs have comparatively more yolk than the microlecithal eggs. The yolk is concentrated in one part of the egg (the vegetal pole ), with the cell nucleus and most of the cytoplasm in the other (the animal pole ). The cell cleavage is uneven, and mainly concentrated in the cytoplasma-rich animal pole. The larger yolk content of the mesolecithal eggs allows for
700-414: A protective shell , either flexible or inflexible. Eggs laid on land or in nests are usually kept within a warm and favorable temperature range while the embryo grows. When the embryo is adequately developed it hatches, i.e., breaks out of the egg's shell. Some embryos have a temporary egg tooth they use to crack, pip, or break the eggshell or covering. The largest recorded egg is from a whale shark and
770-523: A shell and would dry out in the air. Even air-breathing amphibians lay their eggs in water, or in protective foam as with the Coast foam-nest treefrog, Chiromantis xerampelina . Bird eggs are laid by females and incubated for a time that varies according to the species; a single young hatches from each egg. Average clutch sizes range from one (as in condors ) to about 17 (the grey partridge ). Some birds lay eggs even when not fertilized (e.g. hens ); it
SECTION 10
#1732780260072840-427: A taxonomical nightmare, with ten currently accepted subspecies and many more invalid ones. The two remaining " monochrome " species, Mekong and African pied wagtail may be closely related, or a most striking example of convergent evolution . Prehistoric wagtails known from fossils are Motacilla humata and Motacilla major . Wagtails are slender, often colourful, ground-feeding insectivores of open country in
910-495: Is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote ) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the animal hatches. Most arthropods , vertebrates (excluding live-bearing mammals ), and mollusks lay eggs, although some, such as scorpions , do not. Reptile eggs, bird eggs , and monotreme eggs are laid out of water and are surrounded by
980-460: Is any bird of the order Passeriformes ( / ˈ p æ s ə r ɪ f ɔːr m iː z / ; from Latin passer 'sparrow' and formis '-shaped') which includes more than half of all bird species. Sometimes known as perching birds , passerines generally have an anisodactyl arrangement of their toes (three pointing forward and one back), which facilitates perching. With more than 140 families and some 6,500 identified species, Passeriformes
1050-482: Is currently divided into three suborders: Acanthisitti (New Zealand wrens), Tyranni , (suboscines) and Passeri (oscines or songbirds). The Passeri is now subdivided into two major groups recognized now as Corvides and Passerida respectively containing the large superfamilies Corvoidea and Meliphagoidea , as well as minor lineages, and the superfamilies Sylvioidea , Muscicapoidea , and Passeroidea but this arrangement has been found to be oversimplified. Since
1120-414: Is known as oviparity , in which the female lays undeveloped eggs that are externally fertilized by a male. Typically large numbers of eggs are laid at one time (an adult female cod can produce 4–6 million eggs in one spawning) and the eggs are then left to develop without parental care. When the larvae hatch from the egg, they often carry the remains of the yolk in a yolk sac which continues to nourish
1190-425: Is likely to have arisen due to evolution via natural selection. In contrast, many hole-nesting birds have nearly spherical eggs. Many animals feed on eggs. For example, principal predators of the black oystercatcher 's eggs include raccoons , skunks , mink , river and sea otters , gulls , crows and foxes . The stoat ( Mustela erminea ) and long-tailed weasel ( M. frenata ) steal ducks' eggs. Snakes of
1260-906: Is more scant before the Pleistocene, from which several still-existing 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, United States: the Palaeoscinidae with the single genus Palaeoscinis . "Palaeostruthus" eurius (Pliocene of Florida) probably belongs to an extant family, most likely passeroidean . Acanthisitti – New Zealand wrens (1 family containing 7 species, only 2 extant) Tyranni – suboscines (16 families containing 1,356 species) Passeri – oscines (125 families containing 5,158 species) The Passeriformes
1330-416: Is no need of cryptic colors. However, some have suggested that the protoporphyrin markings on passerine eggs actually act to reduce brittleness by acting as a solid-state lubricant. If there is insufficient calcium available in the local soil, the egg shell may be thin, especially in a circle around the broad end. Protoporphyrin speckling compensates for this, and increases inversely to the amount of calcium in
1400-466: Is not a true wagtail; it was named as such by early settlers from England from its superficial similarity in colour and behaviour to the pied wagtail , but belongs to an unrelated genus of birds known as fantails . The genus Motacilla was described by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae . The type species is the white wagtail . Motacilla
1470-446: Is not uncommon for pet owners to find their lone bird nesting on a clutch of unfertilized eggs, which are sometimes called wind-eggs. The default colour of vertebrate eggs is the white of the calcium carbonate from which the shells are made, but some birds, mainly passerines , produce coloured eggs. The colour comes from pigments deposited on top of the calcium carbonate base; biliverdin and its zinc chelate , and bilirubin , give
SECTION 20
#17327802600721540-537: Is proven by several fossils from Germany such as a presumed broadbill ( Eurylaimidae ) humerus fragment from the Early Miocene (roughly 20 mya) of Wintershof , Germany, the Late Oligocene carpometacarpus from France listed above, and Wieslochia , among others. Extant Passeri super-families were quite distinct by that time and are known since about 12–13 mya when modern genera were present in
1610-593: Is the Latin name for the pied wagtail; although actually a diminutive of motare , "to move about", from medieval times it led to the misunderstanding of cilla as "tail". At first glance, the wagtails appear to be divided into a yellow-bellied group and a white-bellied one, or one where the upper head is black and another where it is usually grey, but may be olive, yellow, or other colours. However, these are not evolutionary lineages; change of belly colour and increase of melanin have occurred independently several times in
1680-442: Is the long-tailed widowbird . 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 colored eggs, in contrast with nonpasserines, 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
1750-459: 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. The hind toe ( hallux ) is long and joins the leg at approximately the same level as the front toes. This arrangement enables passerine birds to easily perch upright on branches. The toes have no webbing or joining, but in some cotingas ,
1820-545: Is the largest order of birds and among the most diverse clades of terrestrial vertebrates , representing 60% of birds. Passerines are divided into three suborders : Acanthisitti (New Zealand wrens), Tyranni (composed mostly of South American suboscines), and Passeri (oscines or songbirds). Passerines originated in the Southern Hemisphere around 60 million years ago. Most passerines are insectivorous or omnivorous , and eat both insects and fruit or seeds. The terms "passerine" and "Passeriformes" are derived from
1890-408: Is thought to act as a shock absorber, protecting the calcite shell from fracture during incubation, such as colliding with other eggs in the nest. Most bird eggs have an oval shape , with one end rounded and the other more pointed. This shape results from the egg being forced through the oviduct . Muscles contract the oviduct behind the egg, pushing it forward. The egg's wall is still shapeable, and
1960-399: Is usually motile whereas the female gamete cell, the ovum , is generally larger and sessile . The male and female gametes combine to produce the zygote cell. In multicellular organisms, the zygote subsequently divides in an organised manner into smaller more specialised cells, so that this new individual develops into an embryo . In most animals, the embryo is the sessile initial stage of
2030-657: The Corvida and numerous minor lineages make up songbird diversity today. Extensive biogeographical mixing happens, 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 passerines are relatively small, and their delicate bones do not preserve well. Queensland Museum specimens F20688 ( carpometacarpus ) and F24685 ( tibiotarsus ) from Murgon, Queensland , are fossil bone fragments initially assigned to Passeriformes . However,
2100-527: The Old World . Species of wagtail breed in Africa, Europe and Asia, some of which are fully or partially migratory. Two species also breed in western Alaska, and wintering birds may reach Australia. They are ground nesters, often in rock crevices on steep banks or walls, laying (3–)4–6(–8) speckled eggs at a time. Among their most conspicuous behaviours is a near constant tail wagging, a trait that has given
2170-580: 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 lineages, so new families had to be established, some of theirs – like the stitchbird of New Zealand and the Eurasian bearded reedling – monotypic with only one living species. In the Passeri alone, a number of minor lineages will eventually be recognized as distinct superfamilies. For example,
Wagtail - Misplaced Pages Continue
2240-415: The coelacanths can reach a size of 9 cm (3.5 in) in diameter, and the young go through full development while in the uterus , living on the copious yolk. Animals are commonly classified by their manner of reproduction, at the most general level distinguishing egg-laying (Latin. oviparous ) from live-bearing (Latin. viviparous ). These classifications are divided into more detail according to
2310-631: The crows , do not sound musical to human beings. Some, such as the lyrebird , are accomplished mimics. The New Zealand wrens are tiny birds restricted to New Zealand , at least in modern times; they were long placed in Passeri. 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
2380-445: 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 theirs have been found among comprehensive studies of the living Passeri, though they might be fairly close to some little-studied tropical Asian groups. Nuthatches , wrens , and their closest relatives are currently grouped in
2450-594: The planula , and either develops directly into the adult animals or forms new adult individuals through a process of budding . Microlecithal eggs require minimal yolk mass. Such eggs are found in flatworms , roundworms , annelids , bivalves , echinoderms , the lancelet and in most marine arthropods . In anatomically simple animals, such as cnidarians and flatworms, the fetal development can be quite short, and even microlecithal eggs can undergo direct development. These small eggs can be produced in large numbers. In animals with high egg mortality, microlecithal eggs are
2520-411: The salamanders . Eggs with a large yolk are called macrolecithal. The eggs are usually few in number, and the embryos have enough food to go through full fetal development in most groups. Macrolecithal eggs are only found in selected representatives of two groups: Cephalopods and vertebrates . Macrolecithal eggs go through a different type of development than other eggs. Due to the large size of
2590-456: The scientific name of the house sparrow , Passer domesticus , and ultimately from the Latin term passer , which refers to sparrows and similar small birds. The order is divided into three suborders, Tyranni (suboscines), Passeri (oscines or songbirds), 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
2660-402: The superb lyrebird has 16, and several spinetails in the family Furnariidae have 10, 8, or even 6, as is the case of Des Murs's wiretail . Species adapted to tree trunk climbing such as treecreepers and woodcreeper have stiff tail feathers that are used as props during climbing. Extremely long tails used as sexual ornaments are shown by species in different families. A well-known example
2730-413: The adult body, and by the yolk which the egg provides to nourish the embryo. Vertebrate eggs can be classified by the relative amount of yolk . Simple eggs with little yolk are called microlecithal , medium-sized eggs with some yolk are called mesolecithal , and large eggs with a large concentrated yolk are called macrolecithal . This classification of eggs is based on the eggs of chordates , though
2800-540: The air. Often the sex of the developing embryo is determined by the temperature of the surroundings, with cooler temperatures favouring males. Not all reptiles lay eggs; some are viviparous ("live birth"). Dinosaurs laid eggs, some of which have been preserved as petrified fossils. Among mammals, early extinct species laid eggs, as do platypuses and echidnas (spiny anteaters). Platypuses and two genera of echidna are Australian monotremes . Marsupial and placental mammals do not lay eggs, but their unborn young do have
2870-407: The basic principle extends to the whole animal kingdom . Small eggs with little yolk are called microlecithal. The yolk is evenly distributed, so the cleavage of the egg cell cuts through and divides the egg into cells of fairly similar sizes. In sponges and cnidarians , the dividing eggs develop directly into a simple larva, rather like a morula with cilia . In cnidarians, this stage is called
Wagtail - Misplaced Pages Continue
2940-601: The basis of morphological similarities that, it is now believed, are the result of convergent evolution , not a close genetic relationship. For example, the wrens of the Americas and Eurasia , those of Australia , and those of New Zealand look superficially similar and behave in similar ways, 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. Advances in molecular biology and improved paleobiogeographical data gradually are revealing
3010-492: The biological sense. In placental mammals , the egg itself is void of yolk, but develops an umbilical cord from structures that in reptiles would form the yolk sac. Receiving nutrients from the mother, the fetus completes the development while inside the uterus. Eggs are common among invertebrates , including insects , spiders , mollusks , and crustaceans . All sexually reproducing life, including both plants and animals, produces gametes . The male gamete cell, sperm ,
3080-487: The birds their common name. In spite of the ubiquity of the behaviour and observations of it, the reasons for it are poorly understood. It has been suggested that it may flush up prey, or that it may signal submissiveness to other wagtails. Recent studies have suggested instead that it is a signal of vigilance that may aid to deter potential predators. The genus contains thirteen species. Passerine and see text A passerine ( / ˈ p æ s ə r aɪ n / )
3150-404: The cells of incipient multicellular organisms. The cycle of the egg's formation is started by the gamete ovum being released ( ovulated ) and egg formation being started. The finished egg is then ovipositioned and eventual egg incubation can start. Scientists often classify animal reproduction according to the degree of development that occurs before the new individuals are expelled from
3220-401: The complex tissues that identify amniotes. The eggs of the egg-laying mammals (the platypus and the echidnas ) are macrolecithal eggs very much like those of reptiles . The eggs of marsupials are likewise macrolecithal, but rather small, and develop inside the body of the female, but do not form a placenta . The young are born at a very early stage, and can be classified as a " larva " in
3290-512: The corvoidean and basal songbirds. The modern diversity of Passerida genera is known mostly from the Late Miocene onward 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
3360-476: The crowded cliff ledges on which they breed. Yolks of birds' eggs are yellow from carotenoids , it is affected by their living conditions and diet. Bird eggshells are diverse. For example: Tiny pores in bird eggshells allow the embryo to breathe. The domestic hen 's egg has around 7000 pores. Some bird eggshells have a coating of vaterite spherules , which is a rare polymorph of calcium carbonate. In Greater Ani Crotophaga major this vaterite coating
3430-404: The families in the suborder Tyranni (suboscines) were all well determined but some of the nodes in Passeri (oscines or songbirds) were unclear owing to the rapid splitting of the lineages. Infraorder Eurylaimides : Old World suboscines Infraorder Tyrannides : New World suboscines Parvorder Furnariida Parvorder Tyrannida Relationships between living Passeriformes families based on
3500-650: The genera Dasypeltis and Elachistodon specialize in eating eggs. Brood parasitism occurs in birds when one species lays its eggs in the nest of another. In some cases, the host's eggs are removed or eaten by the female, or expelled by her chick. Brood parasites include the cowbirds and many Old World cuckoos . Like amphibians, amniotes are air-breathing vertebrates , but they have complex eggs or embryos , including an amniotic membrane . Amniotes include reptiles (including dinosaurs and their descendants, birds) and mammals. Reptile eggs are often rubbery and are always initially white. They are able to survive in
3570-494: The individual life cycle, and is followed by the emergence (that is, the hatching) of a motile stage. The zygote or the ovum itself or the sessile organic vessel containing the developing embryo may be called the egg. A recent proposal suggests that the phylotypic animal body plans originated in cell aggregates before the existence of an egg stage of development . Eggs, in this view, were later evolutionary innovations , selected for their role in ensuring genetic uniformity among
SECTION 50
#17327802600723640-411: The larvae for a few days as they learn how to swim. Once the yolk is consumed, there is a critical point after which they must learn how to hunt and feed or they will die. A few fish, notably the rays and most sharks use ovoviviparity in which the eggs are fertilized and develop internally. However, the larvae still grow inside the egg consuming the egg's yolk and without any direct nourishment from
3710-669: The material is too fragmentary and their affinities have been questioned. Several more recent fossils from the Oligocene of Europe, such as Wieslochia , Jamna , Resoviaornis , and Crosnoornis , are more complete and definitely represent early passeriforms, and have been found to belong to a variety of modern and extinct lineages. From the Bathans Formation at the Manuherikia River in Otago , New Zealand, MNZ S42815 (a distal right tarsometatarsus of
3780-536: The mid-2000s, studies have investigated the phylogeny of the Passeriformes and found that many families from Australasia traditionally included in the Corvoidea actually represent more basal lineages within oscines. Likewise, the traditional three-superfamily arrangement within the Passeri has turned out to be far more complex and will require changes in classification. Major " wastebin " families such as
3850-418: The mother also providing direct nourishment. The eggs of fish and amphibians are jellylike. Cartilaginous fish (sharks, skates, rays, chimaeras) eggs are fertilized internally and exhibit a wide variety of both internal and external embryonic development. Most fish species spawn eggs that are fertilized externally, typically with the male inseminating the eggs after the female lays them. These eggs do not have
3920-432: The mother. The mother then gives birth to relatively mature young. In certain instances, the physically most developed offspring will devour its smaller siblings for further nutrition while still within the mother's body. This is known as intrauterine cannibalism . In certain scenarios, some fish such as the hammerhead shark and reef shark are viviparous , with the egg being fertilized and developed internally, but with
3990-421: The norm, as in bivalves and marine arthropods. However, the latter are more complex anatomically than e.g. flatworms, and the small microlecithal eggs do not allow full development. Instead, the eggs hatch into larvae , which may be markedly different from the adult animal. In placental mammals, where the embryo is nourished by the mother throughout the whole fetal period, the egg is reduced in size to essentially
4060-518: The passerine host's egg. The vinous-throated parrotbill has two egg colors, white and blue, to deter the brood parasitic common cuckoo . 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, while in the higher latitudes of the Northern Hemisphere, hole-nesting species like tits can lay up to
4130-890: The phylogenetic analysis of Oliveros et al (2019). Some terminals have been renamed to reflect families recognised by the IOC but not in that study. The IOC families Alcippeidae and Teretistridae were not sampled in this study. Acanthisittidae (New Zealand wrens) Eurylaimidae (eurylaimid broadbills) Philepittidae (asites) Calyptomenidae (African and green broadbills) Pittidae (pittas) Sapayoidae (sapayoa) Melanopareiidae (crescent chests) Conopophagidae (gnateaters) Thamnophilidae (antbirds) Grallariidae (antpittas) Rhinocryptidae (tapaculos) Formicariidae (antthrushes) Scleruridae (leaftossers) Dendrocolaptidae (woodcreepers) Furnariidae (ovenbirds) Pipridae (manakins) Cotingidae (cotingas) Tityridae (tityras, becards) Egg (biology) An egg
4200-413: The pointed end develops at the back. . One hypothesis is that long, pointy eggs are an incidental consequence of having a streamlined body typical of birds with strong flying abilities; flight narrows the oviduct, which changes the type of egg a bird can lay. Cliff-nesting birds often have highly conical eggs. They are less likely to roll off, tending instead to roll around in a tight circle; this trait
4270-509: The second and third toes are united at their basal third. The leg of passerine birds contains an additional special adaptation 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. Most passerine birds have 12 tail feathers but
SECTION 60
#17327802600724340-568: The small size of the eggs does not allow for direct development, and the eggs hatch to a larval stage ("fry"). In terrestrial animals with macrolecithal eggs, the large volume to surface ratio necessitates structures to aid in transport of oxygen and carbon dioxide, and for storage of waste products so that the embryo does not suffocate or get poisoned from its own waste while inside the egg, see amniote . In addition to bony fish and cephalopods, macrolecithal eggs are found in cartilaginous fish , reptiles , birds and monotreme mammals. The eggs of
4410-549: The smallest known bird egg, which measures between 6.35–11.4 millimetres (0.250–0.449 in) long and weighs half of a gram (around 0.02 oz). Some eggs laid by reptiles and most fish, amphibians, insects, and other invertebrates can be even smaller. Reproductive structures similar to the egg in other kingdoms are termed " spores ", or in spermatophytes " seeds ", or in gametophytes "egg cells". Several major groups of animals typically have readily distinguishable eggs. The most common reproductive strategy for fish
4480-416: The soil. For the same reason, later eggs in a clutch are more spotted than early ones as the female's store of calcium is depleted. The color of individual eggs is also genetically influenced, and appears to be inherited through the mother only, suggesting that the gene responsible for pigmentation is on the sex-determining W chromosome (female birds are WZ, males ZZ). It used to be thought that color
4550-944: The southern continents in the early Eocene . The New Zealand wrens are the first to become isolated in Zealandia , and the second split involved the origin of the Tyranni in South America and the Passeri in the Australian continent . The Passeri experienced a great radiation of forms in Australia. A major branch of the Passeri, the parvorder Passerida , dispersed into Eurasia and Africa about 40 million years ago, where they experienced further radiation of new lineages. This eventually led to three major Passerida lineages comprising about 4,000 species, which in addition to
4620-418: The wagtails, and the colour patterns which actually indicate relationships are more subtle. mtDNA cytochrome b and NADH dehydrogenase subunit 2 sequence data (Voelker, 2002) is of limited use: the suspicion that there is a superspecies of probably three white-bellied, black-throated wagtails is confirmed. Also, there is another superspecies in sub-Saharan Africa , three white-throated species with
4690-432: The yolk, the cell division can not split up the yolk mass. The fetus instead develops as a plate-like structure on top of the yolk mass, and only envelopes it at a later stage. A portion of the yolk mass is still present as an external or semi-external yolk sac at hatching in many groups. This form of fetal development is common in bony fish , even though their eggs can be quite small. Despite their macrolecithal structure,
4760-442: Was 30 cm × 14 cm × 9 cm (11.8 in × 5.5 in × 3.5 in) in size. Whale shark eggs typically hatch within the mother. At 1.5 kg (3.3 lb) and up to 17.8 cm × 14 cm (7.0 in × 5.5 in), the ostrich egg is the largest egg of any living bird, though the extinct elephant bird and some non-avian dinosaurs laid larger eggs. The bee hummingbird produces
4830-456: Was applied to the shell immediately before laying, but subsequent research shows that coloration is an integral part of the development of the shell, with the same protein responsible for depositing calcium carbonate, or protoporphyrins when there is a lack of that mineral. In species such as the common guillemot , which nest in large groups, each female's eggs have very different markings, making it easier for females to identify their own eggs on
4900-603: Was later isolated. The African pied wagtail (and possibly the Mekong wagtail ) diverged prior to the massive radiation of the white-bellied black-throated and most yellow-bellied forms, all of which took place during the late Piacenzian (early Late Pliocene), c. 3 mya. Three species are poly- or paraphyletic in the present taxonomical arrangement, and either subspecies need to be reassigned and/or species split up. The western yellow wagtail (AKA blue-headed wagtail, yellow wagtail, and many other names) especially, has always been
#71928