parent_taxon pseudonigrita
The ___MASK19___ or common ___MASK19___ (" ___MASK30___ camelus ") is either one or two species of large flightless birds native to Africa , the only living member ( s ) of the genus " ___MASK30___ ", which is in the ratite family . In 2014 , the Somali ___MASK19___ (" ___MASK30___ molybdophanes ") was recognized as a distinct species . A passerine is any ___MASK13___ of the order Passeriformes , which includes more than half of all ___MASK13___ species . A notable feature of passerines compared to other orders of Aves is the arrangement of their toes , three pointing forward and one back , which facilitates perching . Sometimes known as perching birds or , less accurately , as songbirds , the passerines form one of the most diverse terrestrial vertebrate orders , with over 5 , 000 identified species . It has roughly twice as many species as the largest of the ___MASK3___ orders , the ___MASK70___ . It contains more than 110 families , the second - most of any order of tetrapods ( after Squamata , the scaled reptiles ). The passerines contain several groups of brood parasites such as the viduas , cuckoo - finches , and the cowbirds . Most passerines are omnivorous , while the shrikes are carnivorous . Passer is a genus of sparrows , also known as the true sparrows . The genus includes the house ___MASK57___ and the Eurasian tree ___MASK57___ , some of the most common birds in the world . They are small birds with thick bills for eating seeds , and are mostly coloured grey or brown . Native to the Old World , some species have been introduced throughout the world . The ___MASK21___ , or weavers , are small passerine birds related to the finches . An endotherm ( from Greek  " endon " " within " and  " therm " " heat ") is an organism that maintains its body at a metabolically favorable temperature , largely by the use of heat set free by its internal bodily functions instead of relying almost purely on ambient heat . Such internally generated heat is mainly an incidental product of the ___MASK50___ ' s routine metabolism , but under conditions of excessive cold or low activity an endotherm might apply special mechanisms adapted specifically to heat production . Examples include special - function muscular exertion such as shivering , and uncoupled oxidative metabolism such as within brown adipose tissue . Only birds and mammals are extant universally endothermic groups of animals . Certain lamnid sharks , tuna and billfishes are also endothermic . A songbird is a ___MASK13___ belonging to the clade ___MASK73___ of the perching birds ( Passeriformes ). Another name that is sometimes seen as a scientific or vernacular name is Oscines , from Latin " oscen ", " a songbird ". This group contains some 4 , 000 species found all over the world , in which the vocal organ typically is developed in such a way as to produce a diverse and elaborate ___MASK13___ song . Passerida is , under the Sibley - Ahlquist taxonomy , one of two " parvorders " contained within the suborder ___MASK73___ ( standard taxonomic practice would place them at the rank of infraorder ). While more recent research suggests that its sister parvorder , Corvida , is not a monophyletic grouping , the Passerida as a distinct clade are widely accepted . The true finches are small to medium - sized passerine birds in the family ___MASK16___ . Finches have stout conical bills adapted for eating seeds and often have colourful plumage . They occupy a great range of habitats where they are usually resident and do not migrate . They have a worldwide distribution except for Australia and the polar regions . The bee hummingbird , zunzuncito or Helena hummingbird (" ___MASK43___ helenae ") is a species of hummingbird . The superclass ___MASK48___ ( Ancient Greek s tetrapods , " four - footed "), or the tetrapods , comprises the first four - limbed vertebrates and their descendants , including the living and extinct amphibians , birds , mammals , reptiles and some ancient , exclusively aquatic creatures such as the Acanthostega . Tetrapods evolved from the lobe - finned fishes around 390 million years ago in the middle Devonian Period , with modern tetrapod groups having appeared by the late Devonian , 367 . 5 million years ago . The specific aquatic ancestors of the tetrapods , and the process by which land colonization occurred , remain unclear , and are areas of active research and debate among palaeontologists at present . Birds ( Aves ), also known as avian dinosaurs , are a group of endothermic vertebrates , characterised by feathers , toothless beaked jaws , the laying of hard - shelled eggs , a high metabolic rate , a four - chambered heart , and a lightweight but strong skeleton . Birds live worldwide and range in size from the bee hummingbird to the ___MASK19___ . They rank as the class of tetrapods with the most living species , at approximately ten thousand , with more than half of these being passerines , sometimes known as perching birds or , less accurately , as songbirds . Pseudonigrita is a genus of ___MASK13___ classified in the family Passeridae , or sometimes the family ___MASK21___ . It contains the following species : Grey - capped social weaver ( Pseudonigrita arnaudi ) Black - capped social weaver ( Pseudonigrita cabanisi ) Hummingbirds are birds from the Americas that constitute the family ___MASK69___ . They are among the smallest of birds , most species measuring . Indeed , the smallest extant ___MASK13___ species is a hummingbird , the 5 - cm bee hummingbird weighing less than a U . S . penny ( 2 . 5 g ). Dinosaurs are a diverse group of animals of the clade Dinosauria that first appeared during the Triassic . Although the exact origin and timing of the evolution of dinosaurs is the subject of active research , the current scientific consensus places their origin between 231 and 243 million years ago . They became the dominant terrestrial vertebrates after the Triassic  Jurassic extinction event 201 million years ago . Their dominance continued through the Jurassic and Cretaceous periods and ended when the Cretaceous  Paleogene extinction event led to the extinction of most ___MASK24___ groups 66 million years ago . The ear is the organ of hearing and , in mammals , balance . In mammals , the ear is usually described as having three parts  the outer ear , middle ear and the inner ear . The outer ear consists of the ___MASK23___ and the ear canal . Since the outer ear is the only visible portion of the ear in most animals , the word " ear " often refers to the external part alone . The middle ear includes the tympanic cavity and the three ossicles . The inner ear sits in the bony labyrinth , and contains structures which are key to several senses : the semicircular canals , which enable balance and eye tracking when moving ; the utricle and saccule , which enable balance when stationary ; and the cochlea , which enables hearing . The ears of vertebrates are placed somewhat symmetrically on either side of the head , an arrangement that aids sound localisation . Vertebrates comprise all species of animals within the subphylum ___MASK64___ ( chordates with backbones ). Vertebrates represent the overwhelming majority of the phylum Chordata , with currently about 64 , 000 species described . Vertebrates include the jawless fish and the jawed vertebrates , which include the cartilaginous fish ( sharks and rays ) and the bony fish .