Context: Hummingbirds are birds from the Americas that constitute the family Trochilidae. They are among the smallest of birds, most species measuring . Indeed, the smallest extant bird species is a hummingbird, the 5-cm bee hummingbird weighing less than a U.S. penny (2.5 g)., The heart is a muscular organ in humans and other animals, which pumps blood through the blood vessels of the circulatory system. Blood provides the body with oxygen and nutrients, as well as assists in the removal of metabolic wastes. The heart is located between the lungs, in the middle compartment of the chest.
In humans, other mammals, and birds, the heart is divided into four chambers: upper left and right atria; and lower left and right ventricles. Commonly the right atrium and ventricle are referred together as the "right heart" and their left counterparts as the "left heart". Fish in contrast have two chambers, an atrium and a ventricle, while reptiles have three chambers. In a healthy heart blood flows one way through the heart due to heart valves, which prevent backflow. The heart is enclosed in a protective sac, the pericardium, which also contains a small amount of fluid. The wall of the heart is made up of three layers: epicardium, myocardium, and endocardium.
The heart pumps blood with a rhythm determined by a group of pacemaking cells in the sinoatrial node. These generate a current that causes contraction of the heart, traveling through the atrioventricular node and along the conduction system of the heart. The heart receives blood low in oxygen from the systemic circulation, which enters the right atrium from the superior and inferior venae cavae and passes to the right ventricle. From here it is pumped into the pulmonary circulation, through the lungs where it receives oxygen and gives off carbon dioxide. Oxygenated blood then returns to the left atrium, passes through the left ventricle and is pumped out through the aorta to the systemic circulationwhere the oxygen is used and metabolized to carbon dioxide. The heart beats at a resting rate close to 72 beats per minute. Exercise temporarily increases the rate, but lowers resting heart rate in the long term, and is good for heart health.
Cardiovascular diseases (CVD) are the most common cause of death globally as of 2008, accounting for 30% of deaths. Of these more than three quarters are a result of coronary artery disease and stroke. Risk factors include: smoking, being overweight, little exercise, high cholesterol, high blood pressure, and poorly controlled diabetes, among others. Cardiovascular diseases frequently have no symptoms or may cause chest pain or shortness of breath. Diagnosis of heart disease is often done by the taking of a medical history, listening to the heart-sounds with a stethoscope, ECG, and ultrasound. Specialists who focus on diseases of the heart are called cardiologists, although many specialties of medicine may be involved in treatment., 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 TriassicJurassic extinction event 201 million years ago. Their dominance continued through the Jurassic and Cretaceous periods and ended when the CretaceousPaleogene extinction event led to the extinction of most dinosaur groups 66 million years ago., Australasia, a region of Oceania, comprises Australia, New Zealand, the island of New Guinea, and neighbouring islands in the Pacific Ocean. Charles de Brosses coined the term (as French "Australasie") in "Histoire des navigations aux terres australes" (1756). He derived it from the Latin for "south of Asia" and differentiated the area from Polynesia (to the east) and the southeast Pacific (Magellanica). The bulk of Australasia sits on the Indo-Australian Plate, together with India., 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 ostrich. 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., The ear is the organ of hearing and, in mammals, balance. In mammals, the ear is usually described as having three partsthe outer ear, middle ear and the inner ear. The outer ear consists of the pinna 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., The Australian magpie ("Cracticus tibicen") is a medium-sized black and white passerine bird native to Australia and southern New Guinea. Although once considered to be three separate species, it is now considered to be one, with nine recognised subspecies. A member of the Artamidae, the Australian magpie is classified in the butcherbird genus "Cracticus" and is most closely related to the black butcherbird ("C. quoyi"). It is not, however, related to the European magpie, which is a corvid. The adult Australian magpie is a fairly robust bird ranging from in length, with distinctive black and white plumage, gold brown eyes and a solid wedge-shaped bluish-white and black bill. The male and female are similar in appearance, and can be distinguished by differences in back markings.The male has pure white feathers on the back of the head and the female has white blending to gray feathers on the back of the head. With its long legs, the Australian magpie walks rather than waddles or hops and spends much time on the ground., The beak, bill, or rostrum is an external anatomical structure of birds that is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young. The terms "beak" and "rostrum" are also used to refer to a similar mouth part in some dicynodonts, Ornithischians, cephalopods, cetaceans, billfishes, pufferfishes, turtles, Anuran tadpoles and sirens., The black - backed butcherbird ( Cracticus mentalis ) is a species of bird in the family Artamidae . It is found in Papua New Guinea , Indonesia , and northern Queensland in Australia ., Vertebrates comprise all species of animals within the subphylum Vertebrata (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. , 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 animal'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 bird belonging to the clade Passeri 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 bird song., Currawongs are three species of medium-sized passerine birds belonging to the genus "Strepera" in the family Artamidae native to Australasia. These are the grey currawong ("Strepera versicolor"), pied currawong ("S. graculina"), and black currawong ("S. fuliginosa"). The common name comes from the call of the familiar pied currawong of eastern Australia and is onomatopoeic. They were formerly known as crow-shrikes or bell-magpies. Despite their resemblance to crows and ravens, they are only distantly related to the corvidae, instead belonging to an Afro-Asian radiation of birds of superfamily Malaconotoidea., A passerine is any bird of the order Passeriformes, which includes more than half of all bird 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 mammal orders, the Rodentia. 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., The ostrich or common ostrich ("Struthio camelus") is either one or two species of large flightless birds native to Africa, the only living member(s) of the genus "Struthio", which is in the ratite family. In 2014, the Somali ostrich ("Struthio molybdophanes") was recognized as a distinct species., Peltops is a genus of bird in the family Artamidae. The genus contains two species endemic to the island of New Guinea. The genus was once placed with the monarch flycatchers, but molecular and morphometric studies place it closer to the butcherbirds, possibly as a sister taxon to this group. The genus is named for the Greek "pelte" meaning small shield and "ops" meaning face. The species have also had the common name of shieldbill., The Cracticinae, bellmagpies and allies, gathers together 12 species of mostly crow-like birds native to Australasia and nearby areas., Butcherbirds are magpie-like birds in the genus "Cracticus." They are native to Australasia. The Australian magpie has recently been placed in the same genus, and this new taxonomy has been supported by recent phylogenetic analyses. Together with three species of currawong and two species of peltops, butcherbirds and the Australian magpie form the subfamily Cracticinae in the family Artamidae., The superclass Tetrapoda (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., Feathers are epidermal growths that form the distinctive outer covering, or plumage, on birds. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They are among the characteristics that distinguish the extant birds from other living groups., New Guinea (or, historically, "") is a large Island in the South West Pacific region., The bee hummingbird, zunzuncito or Helena hummingbird ("Mellisuga helenae") is a species of hummingbird., Subject: black-backed butcherbird, Relation: instance_of, Options: (A) 12 (B) animal (C) bee (D) bell (E) bill (F) bird (G) cause (H) chest (I) class (J) complex (K) event (L) extinct (M) extinction (N) family (O) fish (P) fluid (Q) food (R) four (S) genus (T) group (U) health (V) hearing (W) history (X) humans (Y) india (Z) island ([) killing (\) may (]) medicine (^) member (_) nine (`) ocean (a) organ (b) organism (c) period (d) plate (e) process (f) production (g) range (h) rank (i) region (j) research (k) result (l) shield (m) side (n) size (o) skeleton (p) song (q) species (r) system (s) taxon (t) taxonomy (u) temperature (v) three (w) two
Output: taxon