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Ichthyornithines
Ichthyornithes is an extinct group of toothed avialan dinosaurs very closely related to the common ancestor of all modern birds. They are known from fossil remains found throughout the late Cretaceous period of North America, though only two genera, ''Ichthyornis'' and ''Janavis'', are represented by complete enough fossils to have been named. Ichthyornitheans became extinct at the Cretaceous–Paleogene boundary, along with enantiornitheans, all other non-avian dinosaurs, and many other animal and plant groups. Origin and evolution The earliest known ichthyornitheans appear in the fossil record about 95 million years ago, during the Cenomanian age of the Late Cretaceous. Based on fragmentary fossil remains, the two known species present in the Ashville Formation have not been given names, but overall were very similar to ''Ichthyornis dispar''. ''I. dispar'' itself had a very long temporal range, and specimens referred to it or very similar species existed relatively unchanged (o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the more recent 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, Aus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecological Niche
In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources and competitors (for example, by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (for example, limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey). "The type and number of variables comprising the dimensions of an environmental niche vary from one species to another [and] the relative importance of particular environmental variables for a species may vary according to the geographic and biotic contexts". See also Chapter 2: Concepts of niches, pp. 7 ''ff'' A Grinnellian niche is determined by the habitat in which a species lives and its accompanying Behavioral ecology, behavioral adaptations. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apatornis
''Apatornis'' is a genus of ornithuran dinosaurs endemic to North America during the late Cretaceous. It currently contains a single species, ''Apatornis celer'', which lived around the Santonian-Campanian boundary, dated to about 83.5 million years ago. The remains of this species were found in the Smoky Hill Chalk of the Niobrara Formation in Kansas, United States. It is known from a single fossil specimen: a ''synsacrum'', the fused series of vertebrae over the hips. While the known fossil remains are very incomplete, enough has been found to reasonably estimate that the body length was between . The type specimen of ''A. celer'', YPM 1451, was reportedly discovered by Othniel Charles Marsh in October 1872 at Butte Creek in Logan County, Kansas. This location is now recognized as falling between Marker Units 15 and 19 of the Smoky Hill Chalk geological formation. An additional, more complete specimen had also been referred to ''Apatornis celer'' by Marsh.O. C. Marsh. 1873. On ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ambiortus
''Ambiortus'' is an extinct genus of ornithuromorph dinosaurs. The only known species, ''Ambiortus dementjevi'', lived sometime during the Barremian age between 136.4 and 125 million years agoHoltz, Thomas R. Jr. (2012). ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,'Winter 2011 Appendix(PDF). in the Andaikhudag Formation of Mongolia. It was discovered by Yevgeny Kurochkin in 1982. Classification ''Ambiortus dementjevi'' belongs to Ornithuromorpha (the group containing modern birds but not Enantiornithes), according to all published cladistic analyses. However, the exact position of the species within this group has been controversial. Early studies suggested it was a member of Palaeognathae, the group containing modern ratites and tinamou,Kurochkin, (1985). "A true carinate bird from Lower Cretaceous deposits in Mongolia and other evidence of Early Cretaceous birds in Asia." ''Cretaceous Research'', 6: 271-278. but this has not bee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aves
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 common ostrich. There are over 11,000 living species and they are split into 44 orders. More than half are passerine or "perching" birds. Birds have wings 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crown Group
In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. It is thus a way of defining a clade, a group consisting of a species and all its extant or extinct descendants. For example, Neornithes (birds) can be defined as a crown group, which includes the most recent common ancestor of all modern birds, and all of its extant or extinct descendants. The concept was developed by Willi Hennig, the formulator of phylogenetic systematics, as a way of classifying living organisms relative to their extinct relatives in his "Die Stammesgeschichte der Insekten", and the "crown" and "stem" group terminology was coined by R. P. S. Jefferies in 1979. Though formulated in the 1970s, the term was not commonly used until its reintroduction in 2000 by Graham Budd and Sören Jensen. Contents of the crow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neognathae
Neognathae (; ) is an 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 with the oldest known members being ''Teviornis'' and ''Vegavis'', 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 (biology), 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 bat, Chiroptera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaeopteryx
''Archaeopteryx'' (; ), sometimes referred to by its German name, "" ( ''Primeval Bird'') is a genus of bird-like dinosaurs. The name derives from the ancient Greek (''archaîos''), meaning "ancient", and (''ptéryx''), meaning "feather" or "wing". Between the late 19th century and the early 21st century, ''Archaeopteryx'' was generally accepted by palaeontologists and popular reference books as the oldest known bird (member of the group Avialae). Older potential avialans have since been identified, including ''Anchiornis'', ''Xiaotingia'', '' Aurornis'', and '' Baminornis''. ''Archaeopteryx'' lived in the Late Jurassic around 150 million years ago, in what is now southern Germany, during a time when Europe was an archipelago of islands in a shallow warm tropical sea, much closer to the equator than it is now. Similar in size to a Eurasian magpie, with the largest individuals possibly attaining the size of a raven, the largest species of ''Archaeopteryx'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neoaves
Neoaves is a clade that consists of all modern bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...s (Neornithes or Aves) with the exception of Palaeognathae (ratites and kin) and Galloanserae (ducks, chickens and kin). This group is defined in the '' PhyloCode'' by George Sangster and colleagues in 2022 as "the most inclusive crown clade containing '' Passer domesticus'', but not '' Gallus gallus''". Almost 95% of the roughly 10,000 known species of extant birds belong to the Neoaves. The early diversification of the various neoavian groups occurred very rapidly around the Cretaceous–Paleogene extinction event, and attempts to resolve their relationships with each other have resulted initially in much controversy. Phylogeny The early diversification of the various neoavia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelagornithidae
The Pelagornithidae, commonly called pelagornithids, pseudodontorns, bony-toothed birds, false-toothed birds or pseudotooth birds, are a prehistoric family (biology), 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. Most of the common names refer to these bird, birds' most notable trait: tooth-like points on their beak, beak's edges, which, unlike true teeth, contained Volkmann's canals and were outgrowths of the premaxillary and mandible, mandibular bones. Even "small" species of pseudotooth birds were the size of albatrosses; the largest ones had wingspans estimated at 5–6 metres (15–20 ft) and were among the largest flying birds ever to live. They were the dominant seabirds of most oceans throughout most of the Cenozoic, and modern humans apparently missed encountering them only by a tiny measure of evolutionary time: the last known pelagornithids were co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protodontopteryx
''Protodontopteryx'' is a genus of pelagornithid (pseudotooth bird) that lived in New Zealand roughly 62 million years ago, during the early Paleocene epoch. It contains one species, ''Protodontopteryx ruthae''. ''Protodontopteryx'' is the smallest, oldest, and most basal pelagornithid discovered. Discovery and naming The holotype specimen of ''Protodontopteryx ruthae'', CM 2018.124.8, was collected in the Canterbury Region of New Zealand on 11 November 2017 by Leigh Love. It is from the Mt Ellen Member of the Waipara Greensand. The specimen is a partial skeleton including the skull, portions of the limb bones, some vertebrae, and a wing phalanx. The latter two are in a separate block of matrix from the rest, and none of the bones are preserved in articulation; since there exists a possibility the fossil contains bones from two different individuals (and potentially different species), the authors specifically designate the skull as the holotype. Another specimen, CM 2018.124.9 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
