Animals - 4 | Britannica.com Animals (kingdom Animalia), any of a group of multicellular eukaryotic organisms (i.e., as distinct from bacteria, their deoxyribonucleic acid, or DNA, is contained in a membrane-bound nucleus). Browse Subcategories: (255) Displaying 201 - 300 of 800 results Daonella genus of extinct pelecypods (clams) useful as a guide, or index, fossil in Triassic rocks. The shell is characterized by a wide dorsal region and by fine radiating riblike lineations. The shell is circular in outline and may show fine growth lines. de Beer, Sir Gavin English zoologist and morphologist known for his contributions to experimental embryology, anatomy, and evolution. Concerned with analyzing developmental processes, de Beer published Introduction to Experimental Embryology (1926), in which he noted that... decapod (order Decapoda), any of more than 8,000 species of crustaceans (phylum Arthropoda) that include shrimp, lobsters, crayfish, hermit crabs, and crabs.

The presence of five pairs of thoracic legs (pereiopods) is the basis for the name decapod (from the... deer Cervidae any of 43 species of hoofed ruminants in the order Artiodactyla, notable for having two large and two small hooves on each foot and also for having antlers in the males of most species and in the females of one species. Deer are native to all... Deltatheridium a genus of extinct mammals found as fossils in rocks from Upper Cretaceous times (about 100–65.5 million years ago) of Asia and, questionably, North America. Deltatheridium was a small insectivorous mammal about the size of a small rat. It is now recognized... Deuterostomia (Greek: “second mouth”), group of animals—including those of the phyla Echinodermata (e.g., starfish, sea urchins), Chordata (e.g., sea squirts, lancelets, and vertebrates), Chaetognatha (e.g., arrowworms), and Brachiopoda (e.g., lamp shells)—classified...

Diatryma extinct, giant flightless bird found as fossils in Early Eocene rocks in North America and Europe (the Eocene Epoch lasted from 57.8 to 36.6 million years ago). Diatryma grew to a height of about 2 1 4 metres (7 feet). Its small wings were not used for... Dicaeidae songbird family, of the order Passeriformes, including the diamondbird and flowerpecker groups. Dictyoclostus genus of extinct brachiopods, or lamp shells, that were common invertebrate forms in the shallow seas of North America from the Carboniferous to the Permian periods (between 359 million and 251 million years ago). Dictyoclostus often grew to large size.... Dielasma genus of extinct brachiopods, or lamp shells, that occur as fossils in rocks deposited in marine environments of Carboniferous to Permian age (between 359 million and 251 million years old). The two small, rather smooth valves of the shell of Dielasma...

dik-dik Madoqua any of four species of dwarf antelopes (tribe Neotragini, family Bovidae) that are adapted for life in the arid zones of eastern Africa. Three species inhabit the Horn of Africa: Guenther’s dik-dik (Madoqua guentheri), Salt’s dik-dik (M. saltiana),... dingo member of the family Canidae native to Australia. Most authorities regard dingos as either a subspecies of the domestic dog (Canis lupus familiaris dingo) or a subspecies of the wolf (C. lupus dingo); however, some authorities consider dingos to be their... dinosaur the common name given to a group of reptiles, often very large, that first appeared roughly 245 million years ago (near the beginning of the Middle Triassic Epoch) and thrived worldwide for nearly 180 million years. Most died out by the end of the Cretaceous... dinosauromorph any of a group of archosaurian reptiles that includes dinosaurs and all other reptiles bearing a closer evolutionary relationship to dinosaurs than to pterosaurs.

Dinosaurs include birds and other theropods, sauropodomorphs, and ornithischians —familiar... dipluran Diplura any of a group of about 800 species of small primitive wingless insects, considered by some entomologists to have features similar to ancestral insects. In some classification schemes, the order Diplura is considered to be in the subclass Apterygota... dipper any of five species of songbirds of the Cinclidae family (order Passeriformes) noted for insect hunting by walking underwater in rushing streams and named for their frequent body bobbing. Among the best-known species are the Eurasian, or white-bellied,... dipteran Diptera any member of an order of insects containing the two-winged or so-called true flies. Although many winged insects are commonly called flies, the name is strictly applicable only to members of Diptera. One of the largest insect orders, it numbers... Discoglossidae family of frogs (order Anura) containing the midwife toad (Alytes, four species) and the painted frog (Discoglossus, six species). Both genera are confined to the Old World, occurring in western Europe and northern Africa.

Discoglossid frogs have been... dodo Raphus cucullatus extinct flightless bird of Mauritius (an island of the Indian Ocean), one of the three species that constituted the family Raphidae, usually placed with pigeons in the order Columbiformes but sometimes separated as an order (Raphiformes).... dog Canis lupus familiaris domestic mammal of the family Canidae (order Carnivora). It is a subspecies of the gray wolf (C. lupus) and is related to foxes and jackals. The dog is one of the two most ubiquitous and popular domestic animals in the world (the... dolphin any of the toothed whales belonging to the families Delphinidae (oceanic dolphins) or Platanistidae (river dolphins). Of the approximately 40 species of dolphins in the Delphinidae, 6 are commonly called whales, including the killer whale and the pilot... domestic cat Felis catus domesticated member of the family Felidae, order Carnivora, and the smallest member of that family.

Like all felids, domestic cats are characterized by supple, low-slung bodies, finely molded heads, long tails that aid in balance, and specialized... domestic pigeon Columba livia bird of the family Columbidae (order Columbiformes) that was perhaps the first bird tamed by man. Figurines, mosaics, and coins have portrayed the domestic pigeon since at least 4500 bc (Mesopotamia). From Egyptian times the pigeon has... dove any of certain birds of the pigeon family, Columbidae (order Columbiformes). The names pigeon and dove are often used interchangeably. Although “dove” usually refers to the smaller, long-tailed members of the pigeon family, there are exceptions: the... dragonfly Anisoptera any of a group of roughly 3,000 species of aerial predatory insects most commonly found near freshwater habitats throughout most of the world. Damselflies (suborder Zygoptera) are sometimes also called dragonflies in that both are odonates... drongo any of approximately 26 species of Old World woodland birds constituting the family Dicruridae (order Passeriformes).

Drongos frequently attack much larger birds (e.g., hawks and crows) that might hurt their eggs or young; innocuous birds (such as doves... duck any of various species of relatively small short-necked, large-billed waterfowl. In true ducks—i.e., those classified in the subfamily Anatinae in the waterfowl family Anatidae—the legs are placed rearward, as in swans, rather than forward, as in geese.... duiker Cephalophini any of 17 or 18 species of forest-dwelling antelopes (subfamily Cephalophinae, family Bovidae) found only in Africa. Duiker derives from the Afrikaans duikerbok (“diving buck”), which describes the sudden headlong flight of duikers flushed... dunnock Prunella modularis a drab, skulking European songbird, a species of accentor belonging to the family Prunellidae. Moving with a jerky, shuffling gait, this abundant but unobtrusive little bird spends much of its time among shrubs and hedgerows but often...

eagle any of many large, heavy-beaked, big-footed birds of prey belonging to the family Accipitridae (order Falconiformes). In general, an eagle is any bird of prey more powerful than a buteo. An eagle may resemble a vulture in build and flight characteristics... echidna Tachyglossidae any of four species of peculiar egg-laying mammals from Australia, Tasmania, and New Guinea that eat and breathe through a bald tubular beak protruding from a dome-shaped body covered in spines. Echidnas have beady eyes and mere slits... echinoderm any of a variety of invertebrate marine animals belonging to the phylum Echinodermata, characterized by a hard, spiny covering or skin. Beginning with the dawn of the Cambrian Period (542 million to 488 million years ago), echinoderms have a rich fossil... ectotherm Any so-called cold-blooded animal; that is, any animal whose regulation of body temperature depends on external sources, such as sunlight or a heated rock surface. The ectotherms include the fish es, amphibian s, reptile s, and invertebrate s. The body...

eel Anguilliformes any of more than 800 species of teleost fishes characterized by elongate wormlike bodies. Anguilliforms include the common freshwater eels as well as the voracious marine morays. General features Regardless of their final habitat, all... eelworm any of several worms of the phylum Nematoda, so called because they resemble miniature eels. The term is most often applied to smaller nematodes that are either free-living or parasitic in plants. Most eelworms are 0.1 to 1.5 millimetres (0.004 to 0.06... eland Taurotragus either of two very large, oxlike African antelopes of the spiral-horned antelope tribe (Tragelaphini, family Bovidae), which also includes the bushbuck and the kudus. The giant, or Derby, eland (Taurotragus derbianus) inhabits woodlands filled... electric eel Electrophorus electricus elongated South American fish that produces a powerful electric shock to stun its prey, usually other fish.

Long, cylindrical, scaleless, and usually gray-brown (sometimes with a red underside), the electric eel can grow to 2.75... elephant Elephantidae largest living land animal, characterized by its long trunk (elongated upper lip and nose), columnar legs, and huge head with temporal glands and wide, flat ears. Elephants are grayish to brown in colour, and their body hair is sparse and... elephant shrew Macroscelidea any of approximately 20 species of rat-sized African mammals named for their long, tapered, and flexible snout (proboscis). All have slim bodies, slender limbs, and very long hind legs and feet. Although they resemble shrews, they are not... elk Cervus elaphus canadensis the largest and most advanced subspecies of red deer (Cervus elaphus), found in North America and in high mountains of Central Asia. It is a member of the deer family, Cervidae (order Artiodactyla). Recent genetic studies suggest... elopiform Elopiformes any member of a group of archaic ray-finned fishes that includes the tarpons (Megalops) and the ladyfishes (Elops).

Elopiforms live in marine and brackish water habitats. A few are prized game fishes, but only the Pacific tarpon (or oxeye)... Elton, Charles English biologist credited with framing the basic principles of modern animal ecology. Early influences Elton was educated first at Liverpool College and then at New College, Oxford, from which he graduated with first-class honours in zoology in 1922.... Emberizidae songbird family in the classification preferred by some authorities, absorbing some groups otherwise placed in the Fringillidae, order Passeriformes. The family Emberizidae includes some species of buntings, finches, grosbeaks, and sparrows and all juncos;... emperor penguin Aptenodytes forsteri largest member of the penguin order (Sphenisciformes), which is known for its stately demeanor and black-and-white coloration. The species gathers together into approximately 40 colonies that settle on ice shelves and landfast ice... emu flightless bird of Australia and second largest living bird: the emu is more than 1.5 metres (5 feet) tall and may weigh more than 45 kg (100 pounds).

The emu is the sole living member of the family Dromaiidae (or Dromiceiidae) of the order Casuariiformes,... endotherm so-called warm-blooded animals; that is, those that maintain a constant body temperature independent of the environment. The endotherms primarily include the birds and mammals; however, some fish are also endothermic. If heat loss exceeds heat generation,... ensign wasp Evaniidae any of a group of wasps (order Hymenoptera) that are so named because the small, oval abdomen is held high like an ensign, or flag. A few hundred species of this widely distributed family have been described. The body, which is black and somewhat... enterocoelomate any animal in which the mesoderm-lined body cavity (coelom) arises in the embryonic stage as an outpocketing of the developing gut (enteron). This form of development, found in echinoderms (e.g., starfishes, sea urchins) and a few other invertebrate...

entoproct any member of the phylum Entoprocta, a group of aquatic invertebrate animals composed of about 150 species and subdivided into four families. Entoprocts occur throughout the world, primarily in marine habitats, although one genus, Urnatella, is a freshwater... Eospirifer genus of extinct brachiopods, or lamp shells, found as fossils in Middle Silurian to Lower Devonian marine rocks (the Silurian Period ended and the following Devonian Period began about 416 million years ago). The genus Eospirifer is closely related... erect-crested penguin Eudyptes sclateri species of crested penguin (genus Eudyptes, order Sphenisciformes) characterized by plumes of yellow feathers extending from the bill to the back of the head, running above each eye (the superciliary stripe); the plumes often stand... Estrildidae songbird family, order Passeriformes, consisting of approximately 140 species of waxbills and other small finchlike birds of the Old World, many of which are favourite cage birds.

Members range in size from 7.5 to 15 cm (3 to 6 inches) long. They have... euglossine bee Euglossini any of a large group of brightly coloured, bees important to the ecology of New World tropical forests. Colour combinations include metallic blues, greens, and bronzes. They are noted for their long tongues and their role in the pollination... Euphemites extinct genus of gastropods (snails) abundant during the Late Carboniferous Period (between 320 and 286 million years ago) in the shallow seas that covered the midcontinental region of North America. Euphemites was a small, globular snail with a broad... Exogyra extinct molluscan genus common in shallow-water marine deposits of the Jurassic and Cretaceous periods (from about 200 million to 65.5 million years ago). Exogyra is characterized by its very thick shell, which attained massive proportions. The left... fairy shrimp any of the crustaceans of the order Anostraca, so called because of their graceful movements and pastel colours. Some grow to 2.5 cm (about 1 inch) or more in length.

They occur in freshwater ponds of Europe, Central Asia, western North America, the... falconiform Falconiformes any of the group of swift, graceful bird s known for their predatory skill as raptors. Included are eagle s, condor s, buzzard s, kite s, caracara s, osprey s, harrier s, accipiter s, vulture s, secretary bird s, falcon s, hawk s, and bateleur... false scorpion any of the 1,700 species of the order Pseudoscorpiones (sometimes Chelonethida) of the arthropod class Arachnida. They resemble true scorpions but are tailless and only 1 to 7.5 mm (0.04 to 0.3 inch) long. The chelicerae (first pair of appendages) bear... feather the component structure of the outer covering and flight surfaces of all modern birds. Unique to birds, feathers apparently evolved from the scales of birds’ reptilian ancestors. The many different types of feathers are variously specialized for insulation,...

feathered dinosaur any of a group of theropod (carnivorous) dinosaurs, including birds, that evolved feathers from a simple filamentous covering at least by the Late Jurassic Period (about 161 million to 146 million years ago). Similar structures have been reported on... feline Felidae any of 37 cat species that among others include the cheetah, puma, jaguar, leopard, lion, lynx, tiger, and domestic cat. Cats are native to almost every region on Earth, with the exception of Australia and Antarctica. They are carnivorous mammal... ferret either of two species of carnivores, the common ferret and the black-footed ferret, belonging to the weasel family (Mustelidae). Common ferret The common ferret (Mustela putorius furo) is a domesticated form of the European polecat, which it resembles... Fibiger, Johannes Danish pathologist who received the Nobel Prize for Physiology or Medicine in 1926 for achieving the first controlled induction of cancer in laboratory animals, a development of profound importance to cancer research. A student of the bacteriologists...

filarial worm any of a group of parasitic worms of the family Filariidae (phylum Nematoda) that usually require two hosts, an arthropod (the intermediate host) and a vertebrate (the primary host), to complete the life cycle. The larval phase occurs within the body... finch any of several hundred species of small conical-billed, seed-eating songbirds (order Passeriformes). Well-known or interesting birds classified as finches include the bunting, canary, cardinal, chaffinch, crossbill, Galapagos finch, goldfinch, grass... Fiordland penguin Eudyptes pachyrhynchus species of crested penguin (genus Eudyptes, order Sphenisciformes) characterized by a thick stripe of pale yellow feather plumes above each eye (the superciliary stripe) that extends from the bill to the rear of the head. The terminal... fish any of more than 30,000 species of vertebrate animals (phylum Chordata) found in the fresh and salt waters of the world.

Living species range from the primitive, jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the... fish louse any member of the crustacean subclass Branchiura, a group of parasites of migratory marine and freshwater fishes. Of the approximately 120 known species, most belong to the genus Argulus. The fish louse has a very distinctive oval-shaped, flattened body... flamingo Phoenicopteriformes any of six species of tall, pink wading birds with thick downturned bills. Flamingos have slender legs, long, graceful necks, large wings, and short tails. They range from about 90 to 150 cm (3 to 5 feet) tall. Flamingos are highly... flatworm any of the phylum Platyhelminthes, a group of soft-bodied, usually much flattened invertebrates. A number of flatworm species are free-living, but about 80 percent of all flatworms are parasitic— i.e., living on or in another organism and securing nourishment...

flea Siphonaptera any of a group of bloodsucking insects that are important carriers of disease and can be serious pests. Fleas are parasites that live on the exterior of the host (i.e., are ectoparasitic). As the chief agent transmitting the Black Death... flightless bird any of several birds that have, through evolution, lost the ability to fly as they adapted to new environmental circumstances. Most living forms belong to the order Struthioniformes (a group that includes the ostrich, the rhea, the cassowary, the kiwi,... flounder any of numerous species of flatfishes belonging to the families Achiropsettidae, Pleuronectidae, Paralichthyidae, and Bothidae (order Pleuronectiformes). The flounder is morphogenetically unusual. When born it is bilaterally symmetrical, with an eye... fluke any member of the invertebrate class Trematoda (phylum Platyhelminthes), a group of parasitic flatworms that probably evolved from free-living forms millions of years ago. There are more than 10,000 species of flukes. They occur worldwide and range in...

fly Diptera any of several thousand species of insects characterized by the use of only one pair of wings for flight and the reduction of the second pair of wings to knobs (called halteres) used for balance. The term fly is commonly used for almost any small... flying lemur Dermoptera either of the two species of primitive gliding mammals found only in Southeast Asia and on some of the Philippine Islands. Flying lemurs resemble large flying squirrels, as they are arboreal climbers and gliders that have webbed feet with... flying squirrel Pteromyinae any of 43 species of gliding squirrel s. Two species are North American, two live in northern Eurasia, and all others are found in the temperate and tropical forests of India and Asia. Although these rodents do not fly, glides of up to 450... flyway route used regularly by migrating birds, bats, or butterflies. The large majority of such migrants move from northern breeding grounds to southern wintering grounds and back, and most of the well-used flyways follow north-south river valleys (e.g., the...

Forbes, Edward British naturalist, pioneer in the field of biogeography, who analyzed the distribution of plant and animal life of the British Isles as related to certain geological changes. While a medical student at Edinburgh, Forbes embarked upon a botanical tour... fox any of various members of the dog family (Canidae) resembling small to medium-sized bushy-tailed dogs with long fur, pointed ears, and narrow snouts. In a restricted sense, the name refers to the 10 or so species classified as “true” foxes (genus Vulpes),... Fringillidae songbird family, order Passeriformes, sometimes collectively termed New World seedeaters. The group includes grosbeaks, longspurs, cardueline finches, and chaffinches. The relationships of seed-eating birds are the subject of great disagreement, many... frog any of various tailless amphibians belonging to the order Anura. Used strictly, the term may be limited to any member of the family Ranidae (true frogs), but more broadly the name frog is often used to distinguish the smooth-skinned, leaping anurans...

Galapagos penguin Spheniscus mendiculus species of penguin (order Sphenisciformes) characterized by the presence of a narrow C-shaped band of white feathers that extends from the eye to the chin on each side of the head and a single band of black feathers that cuts across... Galapagos shark Carcharhinus galapagensis shark species belonging to the family Carcharhinidae. Galapagos sharks are considered to be a circumtropical species with strong preferences for warm, clear waters near reef systems or oceanic islands and generally over continental... gall wasp Cynipinae any of a group of wasps in the family Cynipidae (order Hymenoptera) that are notable for their ability to stimulate the growth of galls (tissue swellings) on plants. Some gall wasp species are gall inquilines, meaning they do not cause the... galliform Galliformes any of the gallinaceous (that is, fowl-like or chickenlike) birds.

The order includes about 290 species, of which the best-known are the turkeys, chickens, quail, partridge, pheasant and peacock (Phasianidae); guinea fowl (Numididae); and... gasterosteiform Gasterosteiformes any member of a group of fishes characterized generally by tubular mouths, soft fin rays, pelvic fins located on the abdomen, an air bladder without a duct to the gut, and a primitive kidney. Gill structures are somewhat degenerate.... Gastrioceras genus of extinct cephalopods (animals related to the modern squid, octopus, and nautilus), found in Pennsylvanian marine rocks over a wide area, including North America and Great Britain (the Pennsylvanian Subperiod began 318 million years ago and lasted... gastropod any member of more than 65,000 animal species belonging to the class Gastropoda, the largest group in the phylum Mollusca. The class is made up of the snails, which have a shell into which the animal can generally withdraw, and the slugs —snails whose...

gastrotrich any of about 500 species of the phylum Gastrotricha, a group of microscopic aquatic invertebrates that live in the spaces between sand grains and soil particles and on the outer coverings of aquatic plants and animals. They occur in salt water and freshwater... gazelle any of several fleet, medium-sized antelopes with slender, evenly developed limbs, level backs, and long necks. Most gazelles are tan-coloured, with white underparts and rump patch, a dark side stripe, and contrasting facial markings. They inhabit the... gecko any lizard of the family Gekkonidae, which contains over 100 genera and nearly 1,000 species. Geckos are mostly small, usually nocturnal reptiles with a soft skin. They also possess a short stout body, a large head, and typically well-developed limbs.... gentoo penguin Pygoscelis papua species of penguin (order Sphenisciformes) characterized by a band of white feathers extending across the top of the head from just above each eye. Other distinguishing features include a black throat, a brush tail that is large in comparison...

gerbil Gerbillinae any of more than 110 species of African, Indian, and Asian rodents, including sand rats and jirds, all of which are adapted to arid habitats. One Mongolian species (Meriones unguiculatus) is a gentle and hardy animal that has become a popular... gerenuk Litocranius walleri the longest-necked member of the gazelle tribe (Antilopini, family Bovidae), a browsing antelope of the lowland arid thornbush of the Horn of Africa. The gerenuk’s shoulder height is 80–105 cm (31–41 inches), and the animal weighs... Gesner, Conrad Swiss physician and naturalist, best known for his systematic compilations of information on animals and plants. Education and career Noting his learning ability at an early age, his father, an impecunious furrier, placed him for schooling in the household... giant panda Ailuropoda melanoleuca bearlike mammal inhabiting bamboo forests in the mountains of central China.

Its striking coat of black and white, combined with a bulky body and round face, gives it a captivating appearance that has endeared it to people worldwide.... gibbon Hylobatidae any of a dozen or so species of small apes found in the tropical forests of Southeast Asia. Gibbons, like the great apes (gorillas, orangutans, chimpanzees, and bonobos), have a humanlike build and no tail, but gibbons seem to lack higher... giraffe Giraffa any of four species in the genus Giraffa of long-necked, cud-chewing, hoofed mammals of Africa, with long legs and a coat pattern of irregular brown patches on a light background. Giraffes are the tallest of all land animals; males (bulls) may... gizzard in many birds, the hind part of the stomach, especially modified for grinding food. Located between the saclike crop and the intestine, the gizzard has a thick muscular wall and may contain small stones, or gastroliths, that function in the mechanical...

The origins of crown group birds: molecules and fossils - Mayr - 2014 - Palaeontology - Wiley Online Library The origins of crown group birds: molecules and fossils Authors Citing literature Abstract Knowledge of the evolutionary history of crown group birds (Neornithes) has significantly improved through emerging congruence among phylogenetic hypotheses and the description of numerous new Palaeogene stem group representatives. However, controversies still persist about the precise interrelationships of many extant and fossil taxa and about the timing of the diversification of the neornithine crown group. Using the example of Phaethontiformes (tropicbirds) and Psittaciformes (parrots), it is shown how new sequence-based phylogenies may shed light on the relationships of fossils with an unexpected character mosaic, and how such fossils can improve our understanding of character evolution in morphologically disparate avian taxa. The earliest occurrences of neornithine birds are plotted on a current phylogeny.

As noted by previous authors, an extensive diversification of neornithine birds before the latest Cretaceous is not supported by the fossil record, and the existence of essentially modern-type representatives of Telluraves (the clade including most arboreal birds) in the Cretaceous, such as suggested from molecular calibrations, is highly unlikely. Standard PDF (896.9 KB) There now exists a robust framework for major avian clades, with molecular analyses confirming earlier morphology-based hypotheses and detecting novel clades that were not obtained in analyses of anatomical data before. Numerous new Palaeogene fossils further provided direct insights into the early stages of neornithine evolution. An integration of these different data, however, has only recently begun, and controversies persist about the affinities of a number of extant and fossil taxa as well as the timing of early neornithine diversification (Mayr 2009 ; Fjeldså 2013 ).

Interestingly, the earliest neornithine divergences are among the best resolved ones, with Palaeognathae (tinamous, ostriches and allies) and Galloanseres (land- and waterfowl) being unanimously considered successive sister groups of all other neornithine birds, the Neoaves (Mayr and Clarke 2003 ; Ericson et al. 2006 ; Livezey and Zusi 2007 ; Hackett et al. 2008 ). The interrelationships within the latter remain incompletely resolved, but several clades are congruently obtained in multiple studies of independent data. In particular, two major neoavian clades are well supported by comprehensive analyses of sequence data, both also being broadly congruent with earlier hypotheses based on morphological studies (Fig. 1 ; Ericson et al. 2006 ; Hackett et al. 2008 ; Kimball et al. 2013 ; McCormack et al. 2013 ; Yuri et al. 2013 ). One of these was termed ‘Telluraves’ by Yuri et al.

( 2013 ) and comprises the traditional Anomalogonatae sensu Beddard ( 1898 ) that is predominantly arboreal taxa lacking the ambiens muscle, as well as Psittaciformes (parrots), the paraphyletic ‘Falconiformes’ (diurnal birds of prey) and Cariamiformes (seriemas), which have previously not been considered closely related to anomalogonatous birds. Evidence concerning the exact interrelationships of the taxa within Telluraves is ambiguous, but a clade including Piciformes (woodpeckers and allies) and the paraphyletic ‘Coraciiformes’ (rollers and allies, except Leptosomidae (courol)) is well supported, and Trogoniformes (trogons) appear to be its sister taxon (Hackett et al. 2008 ; Kimball et al. 2013 ). Figure 1. Download Powerpoint slide Three phylogenies of neornithine birds based on molecular and morphological data. A, tree obtained from an analysis of 19 nuclear loci (Hackett et al. 2008 ).

B, tree resulting from an analysis of 2954 morphological characters (Livezey and Zusi 2007 ). C, plausible consensus phylogeny preferred in the current study (see text and Mayr 2011a ; Kimball et al. 2013 ; McCormack et al. 2013 ; Yuri et al. 2013 ). Taxa of the ‘Metaves’ clade are marked in red, the remaining Neoaves in blue; the coloured boxes highlight taxa of Telluraves (orange), Aequornithes (green) and Strisores (mauve). Another clade that is well corroborated in molecular analyses was termed ‘Aequornithes’ (Mayr 2011a ) and includes various aquatic and semi-aquatic taxa, that is, Gaviiformes (loons), Procellariiformes (tubenoses and allies), Sphenisciformes (penguins), as well as the paraphyletic ‘Ciconiiformes’ (storks and allies) and most (see below) ‘Pelecaniformes’ (pelicans and allies).

A similar clade was obtained in analyses of morphological data (Mayr and Clarke 2003 ; Livezey and Zusi 2007 ) and had already been outlined by Fürbringer ( 1888 , pls. 27–30; converted into a cladogram by Mayr 2011a , fig. 2 a that was redrawn by Fjeldså 2013 , p. 82). Analyses of different kinds of molecular data further resulted in a clade including apodiform birds (swifts and hummingbirds) and the paraphyletic ‘Caprimulgiformes’ (nightjars and allies), for which the term ‘Strisores’ was resurrected. Other highly corroborated clades that are obtained in sequence-based analyses are truly novel, with sister group relationship between Phoenicopteriformes (flamingos) and Podicipediformes (grebes) being the most notable example (see Mayr 2014 for a recent review). Concerning the position of a number of other taxa, however, there is considerable conflict between different data sets.

The recently proposed ‘Metaves’ clade, for example, which includes morphologically very divergent avian groups at the base of Neoaves (Fig. 1 A), appears to be an artefact of a single gene (beta-fibrinogen) and was not corroborated in analyses excluding these sequences (Mayr 2011a ; Kimball et al. 2013 ; McCormack et al. 2013 ). Moreover, there are a number of oddball taxa, whose phylogenetic position depends on sequence alignment and the settings of the analyses, and for which no congruent phylogenetic hypotheses exist, such as Phaethontiformes (tropicbirds), Opisthocomiformes (hoatzin) and Eurypygiformes (sunbittern and kagu). A plausible consensus phylogeny is shown in Figure 1 C, and this tree topology forms the base of the following considerations. In the current dominance of sequence-based analyses, it cannot be overemphasized that many of the strongly supported clades derived from molecular data are broadly congruent with phylogenetic hypotheses previously proposed from studies of morphological characters.

The fact that morphological features do reflect the interrelationships of birds is of significance, because the comprehensive Palaeogene fossil record of birds can only be set into a phylogenetic context through study of osteological characters. However, these morphological data often show a high degree of homoplasy, in which case independent evidence from sequence-based analyses help to decide between conflicting phylogenetic hypotheses. Here, the potential benefits of an integrative consideration of sequence-based phylogenies and fossils are discussed using the example Phaethontiformes and putative Eocene stem group representatives of Psittaciformes. I further comment on the timing of early neornithine divergences from a fossil perspective and on some general patterns of early neornithine evolution. Institutional abbreviations GU/RSR/VAS, H.N.B. Garhwal University, Department of Geology, Uttarakhand, India; NHMUK, Natural History Museum, London; SMF, Senckenberg Research Institute, Frankfurt; SMNK, Staatliches Museum für Naturkunde Karlsruhe, Germany.

Fossils and the new molecular phylogenies Aequornithes and the affinities of Phaethontiformes Tropicbirds were long assigned to the paraphyletic ‘Pelecaniformes’, but well-corroborated molecular phylogenies indicate that the two key characters traditionally used to define this latter taxon, a gular pouch and a totipalmate foot, evolved convergently in at least Pelecanidae and the clade including Fregatidae and Suloidea (Ericson et al. 2006 ; Hackett et al. 2008 ). The position of Phaethontiformes in phylogenies based on molecular data is very inconsistent. In studies including beta-fibrinogen sequences, tropicbirds resulted in varying positions in the ‘Metaves’ clade (Fain and Houde 2004 ; Ericson et al. 2006 ; Hackett et al. 2008 ). Other molecular data show them to be the sister taxon of Procellariiformes (Cracraft et al. 2004 , fig.

27.4), Ardeidae (herons; Cracraft et al. 2004 , fig. 27.6), Musophagiformes (turacos; Ericson et al. 2006 , fig. ESM-6), Opisthocomiformes (hoatzin; Ericson et al. 2006 , fig. ESM-3), Strigidae (owls; Ericson et al. 2006 , fig. ESM-5), Eurypygiformes (McCormack et al. 2013 , fig. 2 ; Yuri et al. 2013 , fig. 3 ) or Mesitornithidae (mesites; Kimball et al. 2013 , fig. 5 A).

Most of these placements received only weak support, but the evidence for a sister group relationship to Eurypygiformes, that is, the clade including Eurypygidae (sunbittern) and Rhynochetidae (kagu), was considered strong enough to ‘spark further research into shared morphological characteristics of tropicbirds, the sunbittern and the kagu’ (McCormack et al. 2013 , p. 7). In part, this optimism may have stemmed from the fact that morphological apomorphies were identified for another unexpected grouping resulting from molecular analyses, that is, Mirandornithes, the taxon including flamingos and grebes. However, molecular evidence for this latter clade is far less controversial, and, disregarding obvious feeding and locomotory specializations, the morphology of flamingos and grebes is not very dissimilar.

Tropicbirds, by contrast, show hardly any derived similarity to eurypygiform birds, with analyses of morphological data supporting their position within Aequornithes, as sister taxon of either Procellariiformes (Smith 2010 ) or ‘pelecaniform’ birds (Livezey and Zusi 2007 ). The fossil record of tropicbirds is limited, but the earliest stem group representatives are well represented. These are Prophaethon from the early Eocene of England and Lithoptila from the late Paleocene – early Eocene of Morocco (Harrison and Walker 1976 ; Bourdon et al. 2005 , 2008 ). Identification and phylogenetic assignment of both taxa is unchallenged and supported by their inclusion in phylogenetic analyses (Bourdon et al. 2005 ; Smith 2010 ). Unlike extant Phaethontiformes, Prophaethon exhibits very long and slitlike nostrils (Fig.

2 A), which are likely to be plesiomorphic for Phaethontiformes and were considered a derived characteristic of nongaviiform Aequornithes, in which the closed nasal openings of the adults form a marked nasal furrow (Mayr 2011a ; the upper beak of Lithoptila is unknown). Long nostrils are also found in eurypygiform birds (Fig. 2 D), but these are distinguished from those found in Aequornithes and Prophaethon in that they do not reach into the tip of the beak and display the schizorhinal condition, that is, reach caudally beyond the nasofrontal hinge. Figure 2. Download Powerpoint slide Left humerus (A–E), coracoid (F–J) and tarsometatarsus (K–P) of Falconidae, Strigiformes, Messelasturidae, Vastanavidae, Psittacidae and Passeriformes. A, Milvago chimango (Falconidae; SMF 1524).

B, G, M, Messelastur gratulator from the middle Eocene of Messel (Messelasturidae; SMF-ME 11348). C, H, N, Vastanavis sp. from the early Eocene of India (Vastanavidae); C, GU/RSR/VAS 1803; H, GU/RSR/VAS 1254, N, GU/RSR/VAS 1809 (right side, reversed to facilitate comparisons). D, O, Ara chloroptera (Psittacidae; SMF 2032). F, Caracara plancus (Falconidae; SMF 6441). K, Asio clamator (Strigidae; SMF 4134). I, Amazona festiva (Psittacidae; SMF 3746). L, Micrastur ruficollis (Falconidae; SMF 9812). E, J, P, Corvus frugilegus (Corvidae; SMF 323).

Abbreviations: csc, scapular cotyla; fns, foramen nervi supracoracoidei; hyp, hypotarsal sulcus; ung, ungual phalanx. Scale bars represent 10 mm. Psittaciform affinities of messelasturids and halcyornithids are mainly supported by derived features of the zygodactyl foot (Mayr 2011b ), whereas derived resemblances to Falconidae/Strigiformes concern the presence of long supraorbital processes of the skull (Fig. 3 C–F) and the morphology of the hypotarsus, which exhibits a single wide sulcus rather than two sulci/canals as in crown group and other stem group Psittaciformes (Fig. 4 K–M); Messelasturidae further feature raptorlike ungual phalanges (Fig. 4 M).

If Eufalconimorphae, that is, a clade (Falconidae + (Psittaciformes + Passeriformes)), is corroborated by future analyses, and if messelasturids and halcyornithids are indeed stem group representatives of Psittaciformes, the derived features shared by these fossil taxa and Falconidae were either already present in the stem species of Eufalconimorphae and lost in other psittaciform birds and Passeriformes/Zygodactylidae, or they evolved convergently in Falconidae and the fossil taxa. Alternatively, these features may constitute apomorphies of a clade including messelasturids, halcyornithids and Falconidae, in which case assignment of the fossil taxa to Psittaciformes would be incorrect and the parrotlike characters would show homoplasy within Eufalconimorphae. However, it has been detailed that retroposon insertions are not homoplasy-free (Braun et al. 2011 ; Han et al. 2011 ), and Coliiformes proved difficult to place in analyses of nuclear sequence data (Fig.

3 G–L; Wang et al. 2012 ). Furthermore, an Eufalconimorphae clade did not result from an analysis of complete mitochondrial genomes, which supported sister group relationship between Psittaciformes and Strigiformes (Pacheco et al. 2011 , Coliiformes were not included in this study; Fig. 3 J). Whereas the foot of falcons is anisodactyl as in most other birds, owls exhibit a semi-zygodactyl foot. The derived morphology of the owl-like tarsometatarsus of messelasturids (Fig. 4 K, M) is in better agreement with the results of analyses based on mitochondrial data, and a sister group relationship of Strigiformes and Psittaciformes, to the exclusion of the morphologically very divergent Passeriformes, would also show morphological data to be less homoplastic than they were in case of a monophyletic Eufalconimorphae.

Because a definitive placement of messelasturids and halcyornithids depends on a robust phylogeny for the extant taxa, psittaciform birds constitute an example where new phylogenetic hypotheses based on molecular data may elucidate the affinities of fossils with an unexpected character mosaic. On the other hand, however, it is just such fossils that may turn out to be crucial for an understanding of character evolution in morphologically disparate avian taxa, and only an integrative consideration of the total evidence will lead to a full understanding of the evolutionary history of these groups. The timing of early neornithine diversification as indicated by the fossil record In addition to the controversial issues of neoavian interrelationships, there are ongoing debates on the timing of the diversification of the avian crown group. Occurrence in the mid-Paleocene of stem group representatives of Sphenisciformes and Strigiformes, two phylogenetically widely separated and morphologically very different taxa, indicates that crown group Neornithes had already begun to diversify in the Late Cretaceous, that is, before the mass extinction events at the K/Pg boundary (Mayr 2009 , 2013 ).

The exact extent of these early ramifications of neornithine phylogeny nevertheless remains contentious (Feduccia 1995 , 2003 ; Benton 1999 ). In Figure 5 , the earliest stem group representatives of neornithine taxa are plotted on a current phylogeny, which shows that there exist numerous Palaeogene records for virtually all neornithine clades, whereas most of the few Cretaceous fossils are of Campanian or Maastrichtian age, and thus stem from just before the K/Pg boundary (Hope 2002 ; Mayr 2009 ; Longrich et al. 2011 ; Ksepka and Boyd 2012 ). The sole exception is Austinornis lentus, which is based on a fragmentary distal tarsometatarsus from the Coniacian/Santonian (Myers 2010 ) Austin Chalk of Texas. Following Clarke ( 2004 ), Austinornis is here tentatively assigned to the stem lineage of Galliformes (Fig. 5 ).

Neither the age nor the phylogenetic affinities of this species are, however, well constrained, and the holotypic tarsometatarsus, the only known bone of the taxon, may possibly belong to the roughly contemporaneous and similar-sized nonneornithine (Clarke 2004 ) species Apatornis celer / Iaceornis marshi, the tarsometatarsus of which is unknown. Figure 5. Download Powerpoint slide Preferred consensus phylogeny (see text and Mayr 2011a ) of extant neornithine clades with earliest fossil occurrences in blue circles; only Mesozoic and Palaeogene fossils are considered; question marks indicate uncertain identification. The green clade marks Telluraves, the pink one Aequornithes, uncertain phylogenetic affinities are indicated by dashed lines.

Divergence dates are hypothetical and represent conservative minimum estimates; the numbers refer to the following fossils (taxa without reference are listed in Mayr 2009 , which should be consulted for further details): 1, Primobucco (GRF); 2, Quasisyndactylus (M); 3, Rupelramphastoides (Rupelian, Germany); 4, Sylphornis (Q); 5, Neanis (GRF); 6, Messelirrisor (LC); 7, Septentrogon (Fur Formation); 8, Primoscens (Zygodactylidae; LC); 9, unnamed taxon (Tingamarra Local Fauna; Mayr 2009 , p.

189); 10, Halcyornis, Messelastur (LC); 11, Sandcoleidae (Willwood Formation, LC); 12, Masillaraptor (M); 13, Berruornis (Walbeck); 14, Milvoides (middle Eocene, erroneously considered late Eocene by Mayr 2009 ); 15, unnamed taxon (Hordle, Hampshire; Mayr 2009 , p.

159); 16, Pelargopappus (Q); 17, Diatropornis (Q); 18, Plesiocathartes (GRF); 19, Itaboravis, Paleopsilopterus (Itaboraí); 20, Eocypselus (FF); 21, Ventivorus (Q); 22, Paraprefica (M); 23, Masillapodargus (M); 24, Fluvioviridavis (GRF); 25, Prefica (GRF); 26, Rhynchaeites (FF); 27, cf. Nycticorax (JQF); 28, Palaeoephippiorhynchus (JQF); 29, Goliathia (JQF); 30, Pelecanus sp. (Lubéron area; Louchart et al.

2011 ); 31, Piscator (Hordle, Hampshire); 32, Masillastega (M); 33, Limnofregata (GRF); 34, Waimanu (Waipara Greensand); 35, unnamed taxon (Chatham Island; Mayr 2009 , p. 22); 36, unnamed taxon (Louisiana; Mayr 2009 , p. 77); 37, Tytthostonyx (Hornerstown Formation); 38, Colymbiculus (Ikovo, Ukraine, Mayr et al. 2013a ); 39, Polarornis (López de Bertodano Formation); 40, Lithoptila (Ouled Abdoun Basin); 41, Chambicuculus (Mourer-Chauviré et al. 2013 ); 42, unnamed taxon (JQF; Mayr 2009 , p.

113); 43, Foro (GRF); 44, new taxon from Paris Basin (Mayr and De Pietri 2014 ); 45, Agnopterus (Paris Gypsum); 46, undescribed taxon from Lubéron area (pers. obs.); 47, Juncitarsus (Bridger Formation); 48, unnamed taxon (M; Mayr 2009 , p. 88); 49, Parvigrus (Lubéron); 50, Eogrus (Irdin Manha Formation); 51, Messelornis (Cernay); 52, Walbeckornis (Walbeck); 53, Leptoganga (Q); 54, Paraortygoides (LC); 55, Palintropus (Lance Formation); 56, Austinornis (Austin Chalk); 57, Anatalavis (LC); 58, cf.

Cimolopteryx (Lance Formation; Elzanowski and Stidham 2011 ); 59, Vegavis (Cape Lamb, Vega Island); 60, Diogenornis (Itaboraí). The putatively earliest neornithine taxon, Austinornis, is marked with an arrow. Abbreviations: FF, Fur Formation; GRF, Green River Formation; JQF, Jebel Qatrani Formation; LC, London Clay; M, Messel; Q, Quercy. Most molecular calibrations date the origin of crown group Neoaves far into the Cretaceous (Brown et al. 2008 ; van Tuinen 2009 ), with even the divergences of the crown groups of morphologically very homogenous taxa, such as Passeriformes and Psittaciformes, having been assumed to have already taken place in the Cretaceous (Nahum et al. 2003 ; Wright et al. 2008 ; Aggerbeck et al. 2014 ).

For passerines, it has recently been detailed that the existence of crown group representatives by the Late Cretaceous would imply an implausible evolutionary stasis and restricted geographical distribution for dozens of million years (no modern-type passerines are known from the comprehensive early Palaeogene fossil record of Europe and North America; Mayr 2013 ). Some of these early, that is, Cretaceous, divergence dates derived from molecular calibrations are due to the use of incorrectly identified or ambiguous taxa as calibration points (Mayr 2009 , 2011c ). Of particular significance for the timing of neornithine divergences is the Late Cretaceous putative anseriform Vegavis, which was hypothesized to be the sister taxon of Anatidae, that is, part of crown group Anseriformes (Clarke et al. 2005 ). The phylogenetic affinities of this very poorly known taxon are, however, far from being well supported (Elzanowski and Stidham 2011 ; Mayr 2013 ), with the same being true for alleged records of Late Cretaceous Gaviiformes (Mayr et al.

2013a ). The absence of unambiguously identified crown group Neornithes from deposits before 70 million years may be an artefact of the incomplete Mesozoic record of birds (Brocklehurst et al. 2012 ), but this would contrast with a comparatively comprehensive record of Late Cretaceous avian taxa outside Neornithes from globally distributed localities (O'Connor et al. 2011 ). Moreover, the temporal occurrence of neornithine taxa broadly agrees with their presumed phylogenetic position, with the earliest fossils belonging to Galloanseres or the early diverging lineages of Aequornithes, that is, Sphenisciformes, Procellariiformes and, possibly, Gaviiformes. None of the Mesozoic avian remains can be assigned to a taxon more deeply nested in neornithine phylogeny, and most Paleocene and many early Eocene birds still display primitive morphologies and cannot be referred with confidence to one of the crown group clades.

In particular, no Cretaceous representatives of Telluraves have been reported so far, and most Paleocene birds as well as all Cretaceous Neornithes belong to aquatic or terrestrial groups, with only one taxon, Eutreptodactylus from the late Paleocene of Brazil, having been identified as an arboreal bird, albeit of unknown affinities (Mayr 2009 ). Telluraves includes omnivorous/frugivorous taxa, which are important plant dispersers, and in light of the marked differences between Late Cretaceous and early Cenozoic angiosperm communities, including a pronounced size increase in early Cenozoic seeds and fruits (Friis et al. 2011 , p. 456), it is highly unlikely that, for example, modern-type parrots and toucans (Ramphastidae) already existed by the Cretaceous (contra Nahum et al. 2003 ; Wright et al. 2008 ).

An early Cenozoic diversification of insect pollinators, such as the lepidopteran Noctuoidea, has also been hypothesized to have possibly triggered the radiation of aerial insectivores within Strisores (Mayr 2009 , p. 119, and compare with Fjeldså 2013 , p. 102). In summary, thus, although the fossil evidence clearly indicates crown group Neornithes had started to diversify before the K/Pg boundary, so far only representatives of Galloanseres and Aequornithes have been identified in the Mesozoic record with confidence. To firmly establish a pre-Campanian diversification of crown group Neornithes from a fossil perspective, identification of Austinornis as a stem group representative of Galloanseres needs to be confirmed by future finds. A Cretaceous radiation of the crown group representatives of the arboreal taxa of Telluraves is not supported by the available fossil data and would conflict with the fact that Cretaceous ecosystems are distinguished from Cenozoic ones in many important respects.

Conclusions Despite the fact that an emerging framework of neornithine interrelationships is now broadly accepted, many taxa still defy a congruent and well-based phylogenetic placement (Fig. 1 C). This is especially true for the ‘metavian’ groups, which include a particularly high number of oddball taxa with an unstable phylogenetic position. It may thus be premature to base all-too detailed novel classifications on new molecular or morphology-based phylogenies (Livezey and Zusi 2007 ; Yuri et al. 2013 ). Biogeographical considerations are likewise flawed if only the extant taxa are taken into consideration (Ericson 2012 ), as many of the groups that are today endemic to the Southern Hemisphere, especially South America, had stem group representatives in the Palaeogene of Europe (Mayr 2009 ). In any case, molecular phylogenies as such allow only limited evolutionary inferences beyond issues of interrelationships, divergence dates and biogeography, and a full appreciation of the evolutionary history of birds is only possible if their past diversity is taken into account. The benefits of a complementary consideration of fossil taxa and molecular phylogenies are mutual.

Many Palaeogene birds exhibit character combinations, which are difficult to interpret in traditional phylogenetic frameworks, and well-corroborated phylogenetic hypotheses derived from analyses of sequence data may help to place these fossils into a phylogenetic context. On the other hand, an assessment of the morphologies of fossil stem group representatives is of significance for an understanding of character evolution within novel, sequence-based clades of morphologically widely divergent taxa. Phylogenetic hypotheses based on morphological data are needed for the identification of fossils, but numerical cladistic analyses of morphological data often do not recover clades, which gained strong support from molecular studies. To overcome these difficulties, molecular and morphological data are increasingly combined in a ‘total evidence’ approach (Clarke et al. 2009 ; Ksepka et al. 2011 ; Nesbitt et al. 2011 ; Ksepka and Clarke 2012 ).

This practice aggravates, however, an independent verification of phylogenetic hypotheses, and I consider it a more promising approach to seek for morphological apomorphies of clades that are strongly and congruently supported by different kinds of molecular data, which can then be used to place fossil taxa into a phylogenetic framework (Mayr 2011a ). Acknowledgements I thank Andrew Smith for the invitation to contribute to this review series in Palaeontology and for comments on the manuscript. Sven Tränkner took the photographs. I also thank Daniel Ksepka and A. Smith for comments, which improved the manuscript. Ancillary 2 January 2014 References Aggerbeck, M., Fjeldså, J., Christidis, L., Fabre, P. H. and Jønsson, K. A. 2014. Resolving deep lineage divergences in core corvoid passerine birds supports a proto-Papuan island origin. Molecular Phylogenetics and Evolution, 70, 272–285. Ballmann, P. 1969.

Die Vögel aus der altburdigalen Spaltenfüllung von Wintershof (West) bei Eichstätt in Bayern. Zitteliana, 1, 5–60. Beddard, F. E. 1898. The structure and classification of birds. Green and Co., London, Longmans, 368 pp.

Question: Which single family of birds, not native to Europe, comprises the order Spenisciformes?
Answer: Penguins