Grebes are aquatic diving birds in the order Podicipediformes. Grebes are widely distributed freshwater birds, with some species also found in marine habitats during migration and winter. Some flightless species exist as well, most notably in stable lakes. The order contains a single family, the Podicipedidae, which includes 22 species in six extant genera. Although, superficially, they resemble other diving birds such as loons and coots, they are most closely related to flamingos, as supported by morphological, molecular and paleontological data. Many species are monogamous and are known for their courtship displays, with the pair performing synchronized dances across the water's surface. The birds build floating vegetative nests where they lay several eggs. About a third of the world's grebes are listed at various levels of conservation concerns—the biggest threats including habitat loss, the introduction of invasive predatory fish and human poaching. As such, three species have gone extinct.
The darters, anhingas, or snakebirds are mainly tropical waterbirds in the family Anhingidae, which contains a single genus, Anhinga. There are four living species, three of which are very common and widespread while the fourth is rarer and classified as near-threatened by the IUCN. The term snakebird is usually used without any additions to signify whichever of the completely allopatric species occurs in any one region. It refers to their long thin neck, which has a snake-like appearance when they swim with their bodies submerged, or when mated pairs twist it during their bonding displays. "Darter" is used with a geographical term when referring to particular species. It alludes to their manner of procuring food, as they impale fishes with their thin, pointed beak. The American darter is more commonly known as the anhinga. It is sometimes called "water turkey" in the southern United States; though the anhinga is quite unrelated to the wild turkey, they are both large, blackish birds with long tails that are sometimes hunted for food.
Palaelodus is an extinct genus of bird of the Palaelodidae family, distantly related to flamingos. They were slender birds with long, thin legs and a long neck resembling their modern relatives, but likely lived very different livestyles. They had straight, conical beaks not suited for filter feeding and legs showing some similarities to grebes. Their precise lifestyle is disputed, with researchers in the past suggesting they may have been divers, while more recent research suggests they may have used their stiff toes as paddles for swimming while feeding on insect larvae and snails. This behavior may have been key in later phoenicopteriforms developing filterfeeding bills. The genus includes between five to eight species and is found across Europe, Australia, New Zealand, Asia and possibly South America. However some argue that most of the taxa named from Europe simply represent differently sized individuals of one single species. Palaelodus was most abundant during the Late Oligocene to Middle Miocene periods, but isolated remains from Australia indicate that the genus, or at least a relative, survived until the Pleistocene.
Osteodontornis is an extinct seabird genus. It contains a single named species, Osteodontornis orri, which was described quite exactly one century after the first species of the Pelagornithidae was. O. orri was named after then-recently deceased naturalist Ellison Orr.
Paraptenodytes is an extinct genus of penguins which contains two or three species sized between a Magellanic penguin and an emperor penguin. They are known from fossil bones ranging from a partial skeleton and some additional material in the case of P. antarcticus, the type specimen for the genus, and a single humerus in the case of P. brodkorbi. The latter species is therefore often considered invalid; a recent study considers it indeed valid, but distinct enough not to belong into Paraptenodytes. The fossils were found in the Santa Cruz and Chubut Provinces of Patagonia, Argentina, in the Gaiman, Monte León and Santa Cruz Formations of Early to Middle Miocene age. Later occurrences are apparently from Late Miocene or possibly even Early Pliocene deposits.
Paraptenodytes brodkorbi is a proposed, but possibly invalid, species of extinct penguin in the genus Paraptenodytes. The bird was probably about the size of a king penguin. Known material is limited to a single humerus, Early Miocene in age, found in the Monte León Formation near Puerto San Julián in Santa Cruz Province, Argentina. It exists as an unnumbered specimen in the collection of the Museo Argentino de Ciencias Naturales.
The Pelagornithidae, commonly called pelagornithids, pseudodontorns, bony-toothed birds, false-toothed birds or pseudotooth birds, are a prehistoric family of large seabirds. Their fossil remains have been found all over the world in rocks dating between the Early Paleocene and the Pliocene-Pleistocene boundary.
Teviornis is a genus of extinct birds. One species has been described, T. gobiensis. It lived in the Maastrichtian stage at the end of the Late Cretaceous period, some 70 million years ago. It is known from fossils collected from the Nemegt Formation of Gobi, south Mongolia.
Eurotrochilus is an extinct genus of stem group hummingbirds (Trochilidae) and are the closest known relatives of the crown group Trochilidae. Despite Eurotrochilus being morphologically very similar to modern hummingbirds, they still retained several primitive features and are not closely related to any specific extant hummingbird in the crown group. There are currently two described species of Eurotrochilus: E. inexpectatus and E. noniewiczi.
Odontopteryx is a genus of the extinct pseudotooth birds or pelagornithids. These were probably rather close relatives of either pelicans and storks, or of waterfowl, and are here placed in the order Odontopterygiformes to account for this uncertainty.
Pelagornis is a widespread genus of prehistoric pseudotooth birds. These were probably rather close relatives of either pelicans and storks, or of waterfowl, and are here placed in the order Odontopterygiformes to account for this uncertainty.
Houornis is a genus of enantiornithean birds from the Jiufotang Formation of Liaoning, People's Republic of China. It is known from a single species, Houornis caudatus, which had been once been classified as a species of Cathayornis, and has also been regarded as a nomen dubium.
Annakacygna is a genus of flightless marine swan from the Miocene of Japan. Named in 2022, Annakacygna displays a series of unique adaptations setting it apart from any other known swan, including a filter feeding lifestyle, a highly mobile tail and wings that likely formed a cradle for their hatchlings in a fashion similar to modern mute swans. Additionally, it may have used both wings and tail as a form of display. All of these traits combined have led the researchers working on it to dub it "the ultimate bird". Two species are known, A. hajimei, which was approximately the size of a black swan, and A. yoshiiensis which exceeded the mute swan in both size and weight. The describing authors proposed the vernacular name Annaka short-winged swan for the genus.
Orienantius ritteri is an extinct genus of enantiornithine bird from the Lower Cretaceous of China.
Thiornis is a fossil genus of Middle Miocene grebe known from a nearly complete specimen from Libros, Spain. Originally classified as a type of moorhen, Thiornis has since been classified as a species of grebe. The overall anatomy of the bird is identical to modern grebes. It contains a single species, T. sociata.
Pliolymbus is a fossil genus of grebe known from the Late Pliocene to Early Pleistocene of United States and Mexico. It is known from a single species, P. baryosteus.
Podicipedini is a tribe of waterbirds belonging to the family Podicipedidae containing the genera Aechmophorus and Podiceps. Members of this tribe of grebes are characterized based on the presence of nuptial plumes and downy young with a bare crown patch. They are more specialized for diving though the anatomy that enables them to do so makes them weaker to stand upright. Further they have much complex mating dance rituals. Based on these characteristics, other possible genera in the clade include Poliocephalus and Rollandia. Indeed a molecular phylogeny by Ogawa et al. (2015) using genetic data from 3 mitochondrial markers found Podiceps to be paraphyletic in respect to Rollandia, as the latter genus is more closely related to several New World species of the former genus. The inclusion of the Neogene genera of Pliolymbus and Thiornis is based on their possible reclassification as junior synonyms as Podiceps.
Podiceps dixi is a possible extinct species of grebe from the United States.
Podiceps miocenicus is an extinct species of large Late Miocene grebe from Moldova.
Podilymbini is a potential tribe of waterbirds belonging to the family Podicipedidae containing the genus Podilymbus and Tachybaptus. In comparison to Podicipedini, podilymbins are characterized by the lack of nuptial plumes and the chicks have rufous down in one or more patches on the crown. They are able to stand upright and move around land more so. The mating displays among these birds are simpler.
