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Vegavis
''Vegavis'' is a genus of extinct bird that lived during the Late Cretaceous (Maastrichtian stage) of Antarctica, some 68 to 66 mya. Among modern birds, most studies show that ''Vegavis'' is most closely related to ducks and geese (Anatidae), but it is not considered to be a direct ancestor of them, although other studies question these results. Taxonomy The holotype specimen of ''Vegavis'' is held by the Museo de La Plata, Argentina. The specimen, cataloged as MLP 93-I-3-1, was found in the López de Bertodano Formation at Cape Lamb on Vega Island, Antarctica, in 1993, but was only described as a new species in 2005 because it consists of the very delicate remains of one bird embedded in a concretion, which had to be meticulously prepared for study. CT scans were utilized to gain a clearer picture of the bone structure without running danger of damaging or destroying the fossil. The genus name, ''Vegavis'', is a combination of the name of Vega Island and "avis", the Lati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vegavis Restoration
''Vegavis'' is a genus of extinct bird that lived during the Late Cretaceous (Maastrichtian stage) of Antarctica, some 68 to 66 mya. Among modern birds, most studies show that ''Vegavis'' is most closely related to ducks and geese (Anatidae), but it is not considered to be a direct ancestor of them, although other studies question these results. Taxonomy The holotype specimen of ''Vegavis'' is held by the Museo de La Plata, Argentina. The specimen, cataloged as MLP 93-I-3-1, was found in the López de Bertodano Formation at Cape Lamb on Vega Island, Antarctica, in 1993, but was only described as a new species in 2005 because it consists of the very delicate remains of one bird embedded in a concretion, which had to be meticulously prepared for study. CT scans were utilized to gain a clearer picture of the bone structure without running danger of damaging or destroying the fossil. The genus name, ''Vegavis'', is a combination of the name of Vega Island and "avis", the Lati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vegaviidae
Vegaviidae is an extinct family of ornithurines, often regarded as stem-anseriforms, which existed during the Late Cretaceous and possibly the Paleocene. Fossils attributed to the family have been found in Canada, Chile, New Zealand, and Antarctica. Previously the genera ''Neogaeornis'' and '' Polarornis'' were classified as stem-loons based on the similarities in the anatomy of the leg structure.Hope, S. (2002). "The Mesozoic radiation of Neornithes." Pp. 339-388 in Chiappe, L.M. and Witmer, L. (eds.), ''Mesozoic Birds: Above the Heads of Dinosaurs''.Carolina Acosta Hospitaleche, Javier N. Gelfo, New Antarctic findings of Upper Cretaceous and lower Eocene loons (Aves: Gaviiformes), Annales de Paléontologie Volume 101, Issue 4, October–December 2015, Pages 315–324 However, there were some criticism to these assertions as the material are from incomplete specimens from Antarctica lacking several important loon characteristics.Feduccia, A. (1999). ''The Origin and Evolution of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
López De Bertodano Formation
The Lopez de Bertodano Formation is a geological Formation (geology), formation in the James Ross Island, James Ross archipelago of the Antarctic Peninsula. The strata date from the end of the Late Cretaceous (upper-lower Maastrichtian stage) to the Danian stage of the lower Paleocene, from about 70 to 65.5 million years ago, straddling the Cretaceous-Paleogene boundary. Cretaceous-Paleogene boundary The Cretaceous–Paleogene boundary (K–Pg) crops out on Seymour Island in the upper levels of the Lopez de Bertodano Formation. A small (but significant) iridium anomaly occurs at the boundary on Seymour Island, as at lower latitudes, thought to be fallout from the Chicxulub impactor in the Gulf of Mexico. Directly above the boundary a layer of disarticulated fish fossils occurs, victims of a disturbed ecosystem immediately following the impact event. Multiple reports have described evidence for climatic changes in Antarctica prior to the mass extinction, but the extent to which t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton. Birds live worldwide and range in size from the bee hummingbird to the ostrich. There are about ten thousand living species, more than half of which are passerine, or "perching" birds. Birds have whose development varies according to species; the only known groups without wings are the extinct moa and elephant birds. Wings, which are modified forelimbs, gave birds the ability to fly, although further evolution has led to the loss of flight in some birds, including ratites, penguins, and diverse endemic island species. The digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly seabirds and some waterbirds, have further evolved for swimming. B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the Latin word for the white limestone known as chalk. The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period. Climate During the Late Cretaceous, the climate was warmer than present, although throughout the period a cooling trend is evident. The tropics became restricted to equatorial regions and northern latitudes experienced markedly more seasonal climatic conditions. Geography Due to plate tectonics, the Americas were gradually moving westward, causing the Atlantic Ocean to expand. The Western Interior Seaway divided North America into eastern and western halves; Appalachia and Laramidia. India maintained a northward course towards Asia. In the Southern Hemisphere, Australia and Ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anseriformes
Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which includes over 170 species of waterfowl, among them the ducks, geese, and swans. Most modern species in the order are highly adapted for an aquatic existence at the water surface. With the exception of screamers, males have penises, a trait that has been lost in the Neoaves. Due to their aquatic nature, most species are web-footed. Evolution Anseriformes are one of only two types of modern bird to be confirmed present during the Mesozoic alongside the other dinosaurs, and in fact were among the very few birds to survive their extinction, along with their cousins the galliformes. These two groups only occupied two ecological niches during the Mesozoic, living in water and on the ground, while the toothed enantiornithes were the dominant bird ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syrinx (bird Anatomy)
The syrinx (from the Greek word "σύριγξ" for ''pan pipes'') is the vocal organ of birds. Located at the base of a bird's trachea, it produces sounds without the vocal folds of mammals. The sound is produced by vibrations of some or all of the ''membrana tympaniformis'' (the walls of the syrinx) and the ''pessulus'', caused by air flowing through the syrinx. This sets up a self-oscillating system that modulates the airflow creating the sound. The muscles modulate the sound shape by changing the tension of the membranes and the bronchial openings. The syrinx enables some species of birds (such as parrots, crows, and mynas) to mimic human speech. Unlike the larynx in mammals, the syrinx is located where the trachea forks into the lungs. Thus, lateralization is possible, with muscles on the left and right branch modulating vibrations independently so that some songbirds can produce more than one sound at a time. Some species of birds, such as New World vultures, lack a syrin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australornis
''Australornis'' (Latin: "southern bird") is a genus of extinct seabird discovered in New Zealand. It lived in the Paleocene epoch, 60.5 to 61.6 million years ago (Ma). The type species name originates from ''australis'', Latin for "southern", and ''ornis'', the Greek word for "bird", and ''lovei'' commemorates Leigh Love, an amateur paleontologist who discovered it. ''Australornis'' is one of the oldest flying seabirds. It is also the first non- sphenisciform (penguins and allies) bird fossil discovered from New Zealand for that age. The fossil originates from an era just after the Cretaceous–Paleogene extinction event 66 million years ago. The features of the bird indicate that it does not belong to any of the extant bird families, but to a precursor group or clade which is extinct; hence it is a find of global significance with regard to the evolution of birds. Though the fossil evidence is incomplete to substantiate phylogeny, ''Australornis'' contributes to the emerging ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anatidae
The Anatidae are the biological family of water birds that includes ducks, geese, and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica. These birds are adapted for swimming, floating on the water surface, and in some cases diving in at least shallow water. The family contains around 174 species in 43 genera. (The magpie goose is no longer considered to be part of the Anatidae and is now placed in its own family, Anseranatidae.) They are generally herbivorous, and are monogamous breeders. A number of species undertake annual migrations. A few species have been domesticated for agriculture, and many others are hunted for food and recreation. Five species have become extinct since 1600, and many more are threatened with extinction. Description and ecology The ducks, geese, and swans are small- to large-sized birds with a broad and elongated general body plan. Diving species vary from this in being rounder. Extant s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polarornis
''Polarornis'' is a genus of prehistoric bird, possibly an anserimorph. It contains a single species ''Polarornis gregorii'', known from incomplete remains of one individual found on Seymour Island, Antarctica, in rocks which are dated to the Late Cretaceous (López de Bertodano Formation, about 66 Ma). The discovery of ''Polarornis gregorii'' was first announced by Sankar Chatterjee in 1989, but he did not describe and officially name the species until 2002.Chatterjee, S. (2002). "The morphology and systematics of ''Polarornis'', a Cretaceous loon (Aves: Gaviidae) from Antarctica." Pp. 125-155 in Zhou and Zhang (eds), ''Proceedings of the 5th Symposium of the Society of Avian Paleontology and Evolution, Beijing, 1–4 June 2000''. Beijing: Science Press. The name ''Polarornis'' had been announced unofficially several years prior to its official publication, in Chatterjee's 1997 book ''The Rise of Birds''.Chatterjee, S. (1997). ''The Rise of Birds''. Baltimore: Johns Hopkins Un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neogaeornis
''Neogaeornis'' is a controversial prehistoric genus of diving bird. The single known species, ''Neogaeornis wetzeli'', was described from fossils found in the Campanian to Maastrichtian Quiriquina Formation of Chile. It lived about 70-67 million years ago. It remains known from the single tarsometatarsus described in 1929 by Lambrecht, and today housed in the Paläontologisches Institut und Museum in Kiel, Germany.Chiappe (1991) Taxonomy It is controversial because of its uncertain placement. While clearly related to modern birds, ''N. wetzeli'' might not be a particularly close relative, but rather belong to the Baptornithidae, a member of the flightless and toothed Hesperornithes. If this is so, ''Neogaeornis'' is among the very youngest records of this lineage, and the first one from the Southern Hemisphere. However, the Hesperornithiformes are known to have been birds of the open epicontinental and shelf seas which avoided the outer oceans as surrounded South America at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neognathae
Neognathae (; ) is a infraclass of birds, called neognaths, within the class Aves of the clade Archosauria. Neognathae includes the majority of living birds; the exceptions being the tinamous and the flightless ratites, which belong instead to the sister taxon Palaeognathae. There are nearly 10,000 living species of neognaths. The earliest fossils are known from the very end of the Cretaceous but molecular clocks suggest that neognaths originated sometime in the first half of the Late Cretaceous, about 90 million years ago. Since then, they have undergone adaptive radiation, producing the diversity of form, function, and behavior that exists today. Neognathae includes the order Passeriformes (perching birds), one of the largest orders of land vertebrates, containing some 60% of living birds. Passeriformes is twice as species-rich as Rodentia and about five times as species-rich as Chiroptera (bats), which are the two largest orders of mammals. Neognathae also contains some ve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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