|
Bird Evolution
The evolution of birds began in the Jurassic Period, with the earliest birds derived from a clade of theropod dinosaurs named Paraves. Birds are categorized as a biological class, Aves. For more than a century, the small theropod dinosaur ''Archaeopteryx lithographica'' from the Late Jurassic period was considered to have been the earliest bird. Modern phylogenies place birds in the dinosaur clade Theropoda. According to the current consensus, Aves and a sister group, the order Crocodilia, together are the sole living members of an unranked reptile clade, the Archosauria. Four distinct lineages of bird survived the Cretaceous–Paleogene extinction event 66 million years ago, giving rise to ostriches and relatives (Palaeognathae), waterfowl (Anseriformes), ground-living fowl (Galliformes), and "modern birds" (Neoaves). Phylogenetically, Aves is usually defined as all descendants of the most recent common ancestor of a specific modern bird species (such as the house sparrow, ''P ... [...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] |
Cretaceous–Paleogene Extinction Event
The Cretaceous–Paleogene (K–Pg) extinction event, also known as the K–T extinction, was the extinction event, mass extinction of three-quarters of the plant and animal species on Earth approximately 66 million years ago. The event caused the extinction of all non-avian dinosaurs. Most other tetrapods weighing more than also became extinct, with the exception of some ectothermic species such as sea turtles and crocodilians. It marked the end of the Cretaceous period, and with it the Mesozoic era, while heralding the beginning of the current era, the Cenozoic. In the geologic record, the K–Pg event is marked by a thin layer of sediment called the Cretaceous–Paleogene boundary, K–Pg boundary or K–T boundary, which can be found throughout the world in marine and terrestrial rocks. The boundary clay shows unusually high levels of the metal iridium, which is more common in asteroids than in the Earth's crust. As originally proposed in 1980 by a team of scientists le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dromaeosaur
Dromaeosauridae () is a family of feathered coelurosaurian theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek ('), meaning 'running at full speed', 'swift', and ('), meaning 'lizard'. In informal usage, they are often called raptors (after ''Velociraptor''), a term popularized by the film ''Jurassic Park''; several genera include the term "raptor" directly in their name, and popular culture has come to emphasize their bird-like appearance and speculated bird-like behavior. Dromaeosaurid fossils have been found across the globe in North America, Europe, Africa, Asia and South America, with some fossils giving credence to the possibility that they inhabited Australia as well. The earliest body fossils are known from the Early Cretaceous (145–140 million years ago), and they survived until the end of the Cretaceous (Maastrichtian stage, 66 ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maniraptora
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the non-avian dinosaurs that were more closely related to them than to ''Ornithomimus velox''. It contains the major subgroups Avialae, Dromaeosauridae, Troodontidae, Oviraptorosauria, and Therizinosauria. ''Ornitholestes'' and the Alvarezsauroidea are also often included. Together with the next closest sister group, the Ornithomimosauria, Maniraptora comprises the more inclusive clade Maniraptoriformes. Maniraptorans first appear in the fossil record during the Jurassic Period (see ''Eshanosaurus''), and origin of birds#Phylogeny, survive today as living birds. Description Maniraptorans are characterized by long arms and three-fingered hands (though reduced or fused in some lineages), as well as a "half-moon shaped" (semilunar bone, semi-lunate) bone in the wrist (Carpal bones, carpus). In 2004, Tom Holtz and Halszka Osmólska pointed out six other maniraptoran characteristics relating to specific de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Origin Of Birds
The scientific question of which larger group of animals birds evolved within has traditionally been called the "origin of birds". The present scientific consensus is that birds are a group of maniraptoran theropod dinosaurs that originated during the Mesozoic era. A close relationship between birds and dinosaurs was first proposed in the nineteenth century after the discovery of the primitive bird '' Archaeopteryx'' in Germany. Birds and extinct non-avian dinosaurs share many unique skeletal traits. Moreover, fossils of more than thirty species of non-avian dinosaur with preserved feathers have been collected. There are even very small dinosaurs, such as ''Microraptor'' and ''Anchiornis'', which have long, vaned arm and leg feathers forming wings. The Jurassic basal avialan '' Pedopenna'' also shows these long foot feathers. Paleontologist Lawrence Witmer concluded in 2009 that this evidence is sufficient to demonstrate that avian evolution went through a four-winged stage. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Systematic Biology (journal)
Systematics is the study of the diversification of living forms, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees (synonyms: phylogenetic trees, phylogenies). Phylogenies have two components: branching order (showing group relationships, graphically represented in cladograms) and branch length (showing amount of evolution). Phylogenetic trees of species and higher taxa are used to study the evolution of traits (e.g., anatomical or molecular characteristics) and the distribution of organisms (biogeography). Systematics, in other words, is used to understand the evolutionary history of life on Earth. The word systematics is derived from the Latin word of Ancient Greek origin ''systema,'' which means systematic arrangement of organisms. Carl Linnaeus used 'Systema Naturae' as the title of his book. Branches and applications In the study of biological systematics, researchers use the different branche ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
California Academy Of Sciences
The California Academy of Sciences is a research institute and natural history museum in San Francisco, San Francisco, California, that is among the largest List of natural history museums, museums of natural history in the world, housing over 46 million specimens. The academy began in 1853 as a learned society and still carries out a large amount of original research. The institution is located in Golden Gate Park on the West Side (San Francisco), West Side of San Francisco. Completely rebuilt in 2008, the academy's primary building in Golden Gate Park covers . In early 2020, before the COVID-19 pandemic, the California Academy of Sciences had around 500 employees and an annual revenue of about $33 million. Governance The California Academy of Sciences, California's oldest operating museum and research institution for the natural sciences, is governed by a 41-member board of trustees who are nominated and chosen by the California Academy of Sciences Fellows. The Academy Fello ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neornithes
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 f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
House Sparrow
The house sparrow (''Passer domesticus'') is a bird of the Old World sparrow, sparrow family Passeridae, found in most parts of the world. It is a small bird that has a typical length of and a mass of . Females and young birds are coloured pale brown and grey, and males have brighter black, white, and brown markings. One of about 25 species in the genus ''Passer'', the house sparrow is native to most of Europe, the Mediterranean Basin, and a large part of Asia. Its intentional or accidental introduced species, introductions to many regions, including parts of Australasia, Africa, and the Americas, make it the most widely distributed wild bird. The house sparrow is strongly associated with human habitation, and can live in urban or rural settings. Though found in widely varied habitats and climates, it typically avoids extensive woodlands, grasslands, polar regions, and hot, dry deserts far away from human development. For sustenance, the house sparrow routinely feeds at h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylogenetics
In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data and observed heritable traits of DNA sequences, protein amino acid sequences, and morphology. The results are a phylogenetic tree—a diagram depicting the hypothetical relationships among the organisms, reflecting their inferred evolutionary history. The tips of a phylogenetic tree represent the observed entities, which can be living taxa or fossils. A phylogenetic diagram can be rooted or unrooted. A rooted tree diagram indicates the hypothetical common ancestor of the taxa represented on the tree. An unrooted tree diagram (a network) makes no assumption about directionality of character state transformation, and does not show the origin or "root" of the taxa in question. In addition to their use for inferring phylogenetic pa ... [...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] |
