parent_taxon undina 
Indonesia ( or ; Indonesian : ), officially the Republic of Indonesia , is a unitary sovereign state and transcontinental country located mainly in Southeast Asia with some territories in Oceania . Situated between the Indian and Pacific oceans , it is the world ' s largest island country , with more than seventeen thousand islands . At , Indonesia is the world ' s 14th - largest country in terms of land ___MASK23___ and world ' s 7th - largest country in terms of combined sea and land ___MASK23___ . It has an estimated population of over 260 million people and is the world ' s fourth most populous country , the most populous Austronesian nation , as well as the most populous Muslim - majority country . The world ' s most populous island of Java contains more than half of the country ' s population . The ___MASK26___ or lobe - finned fish ( from Greek  " sarx ", flesh , and  " pteryx ", fin )  sometimes considered synonymous with ___MASK66___ (" fringe - finned fish ", from Greek  " krossos ", fringe )  constitute a clade ( traditionally a class or subclass ) of the bony fish , though a strict cladistic view includes the terrestrial vertebrates . The living sarcopterygians are the coelacanths and lungfish ; additionally , all tetrapods are sarcopterygians or descendants of them . ___MASK92___ is a rare genus of fish that includes two extant species : West Indian Ocean coelacanth (" ___MASK92___ chalumnae ") and the Indonesian coelacanth (" ___MASK92___ menadoensis "). They follow the oldest known living lineage of Sarcopterygii ( lobe - finned fish and tetrapods ), which means they are more closely related to lungfish , reptiles and mammals than to the common ray - finned fishes . They are found along the coastlines of the Indian Ocean and Indonesia . Since there are only two species of coelacanth and both are threatened , it is the most endangered genus of animals in the world . The West Indian Ocean coelacanth is a critically endangered species . Mammals are any vertebrates within the class Mammalia ( from Latin " mamma " " breast "), a clade of endothermic amniotes distinguished from reptiles and birds by the possession of a neocortex ( a region of the brain ), hair , three middle ear bones and mammary glands . The sister group of mammals may be the extinct " Haldanodon ." The mammals represent the only living Synapsida , which together with the ___MASK55___ form the ___MASK76___ clade . The mammals consist of the Yinotheria including monotrema and the Theriiformes including the theria . A genus ( genera ) is a taxonomic rank used in the biological classification of living and fossil organisms in biology . In the hierarchy of biological classification , genus comes above species and below family . In binomial nomenclature , the genus name forms the first part of the binomial species name for each species within the genus . The Late Jurassic is the third epoch of the Jurassic period , and it spans the geologic time from 161 . 2 ± 4 . 0 to 145 . 5 ± 4 . 0 million years ago ( Ma ), which is preserved in Upper Jurassic strata . In European lithostratigraphy , the name " malm " indicates rocks of Late Jurassic age . In the past , this name was also used to indicate the unit of geological time , but this usage is now discouraged to make a clear distinction between lithostratigraphic and geochronologic / chronostratigraphic units . The coelacanths constitute a now rare order of fish that includes two extant species in the genus " ___MASK92___ ": the West Indian Ocean coelacanth primarily found near the Comoro Islands off the east coast of Africa (" ___MASK92___ chalumnae ") and the Indonesian coelacanth (" ___MASK92___ menadoensis "). They follow the oldest known living lineage of Sarcopterygii ( lobe - finned fish and tetrapods ), which means they are more closely related to lungfish , reptiles and mammals than to the common ray - finned fishes . They are found along the coastlines of the Indian Ocean and Indonesia . Since there are only two species of coelacanth and both are threatened , it is the most endangered order of animals in the world . The West Indian Ocean coelacanth is a critically endangered species . Reptiles are tetrapod ( four - limbed vertebrate ) animals in the class Reptilia , comprising today ' s turtles , crocodilians , snakes , amphisbaenians , lizards , tuatara , and their extinct relatives . The study of these traditional ___MASK17___ orders , historically combined with that of modern amphibians , is called herpetology . A fish is any member of a group of organisms that consist of all gill - bearing aquatic craniate animals that lack limbs with digits . They form a sister group to the tunicates , together forming the ___MASK29___ . Included in this definition are the living ___MASK37___ , lampreys , and cartilaginous and bony fish as well as various extinct related groups . Tetrapods emerged within lobe - finned fishes , so cladistically they are fish as well . However , traditionally fish are rendered obsolete or paraphyletic by excluding the tetrapods ( i . e ., the amphibians , reptiles , birds and mammals which all descended from within the same ancestry ). Because in this manner the term " fish " is defined negatively as a paraphyletic group , it is not considered a formal taxonomic grouping in systematic biology . The traditional term pisces ( also ichthyes ) is considered a typological , but not a phylogenetic classification . The Jurassic ( from Jura Mountains ) is a geologic period and system that spans 56 . 3 million years from the end of the Triassic Period million years ago ( ___MASK58___ ) to the beginning of the Cretaceous Period ___MASK58___ . The Jurassic constitutes the middle period of the Mesozoic Era , also known as the Age of Reptiles . The start of the period is marked by the major Triassic  Jurassic extinction event . Two other extinction events occurred during the period : the Pliensbachian / Toarcian event in the Early Jurassic , and the Tithonian event at the end ; however , neither event ranks among the " Big Five " mass extinctions . Africa is the world ' s second - largest and second - most - populous continent . At about 30 . 3 million km² ( 11 . 7 million square miles ) including adjacent islands , it covers 6 % of Earth ' s total surface ___MASK23___ and 20 . 4 % of its total land ___MASK23___ . With 1 . 1 billion people as of 2013 , it accounts for about 15 % of the world ' s human population . The continent is surrounded by the Mediterranean Sea to the north , both the Suez Canal and the Red Sea along the Sinai Peninsula to the northeast , the Indian Ocean to the southeast , and the Atlantic Ocean to the west . The continent includes Madagascar and various archipelagos . It contains 54 fully recognized sovereign states ( countries ), nine territories and two " de facto " independent states with limited or no recognition . The Indonesian coelacanth (" ___MASK92___ menadoensis ", Indonesian : " raja laut ") is one of two living species of coelacanth , identifiable by its brown color . It is listed as vulnerable by the IUCN . The other species , " L . chalumnae " ( West Indian Ocean coelacanth ) is listed as critically endangered . Binomial nomenclature ( also called binominal nomenclature or binary nomenclature ) is a formal system of naming species of living things by giving each a name composed of two parts , both of which use Latin grammatical forms , although they can be based on words from other languages . Such a name is called a binomial name ( which may be shortened to just " binomial "), a binomen or a scientific name ; more informally it is also called a Latin name . The first part of the name identifies the genus to which the species belongs ; the second part identifies the species within the genus . For example , humans belong to the genus " ___MASK41___ " and within this genus to the species " ___MASK41___ sapiens ". The " formal " introduction of this system of naming species is credited to Carl Linnaeus , effectively beginning with his work " Species Plantarum " in 1753 . But Gaspard Bauhin , in as early as 1623 , had introduced in his book " Pinax theatri botanici " ( English , " Illustrated exposition of plants ") many names of genera that were later adopted by Linnaeus . In biology , an organism is any contiguous living system , such as an ___MASK48___ , ___MASK16___ , fungus , archaeon , or bacterium . All known types of organisms are capable of some degree of response to stimuli , reproduction , growth and development and homeostasis . An organism consists of one or more cells ; when it has one cell it is known as a unicellular organism ; and when it has more than one it is known as a multicellular organism . Most unicellular organisms are of microscopic scale and are thus loosely described as microorganisms . Humans are multicellular organisms composed of many trillions of cells grouped into specialized tissues and organs . The lungs are the primary organs of respiration in humans and many other animals including a few fish and some snails . In mammals and most other vertebrates , two lungs are located near the backbone on either side of the heart . Their function in the respiratory system is to extract oxygen from the atmosphere and transfer it into the bloodstream , and to release carbon dioxide from the bloodstream into the atmosphere , in a process of gas exchange . Respiration is driven by different muscular systems in different species . Mammals , reptiles and birds use their musculoskeletal systems to support and foster breathing . In early tetrapods , air was driven into the lungs by the pharyngeal muscles via buccal pumping , a mechanism still seen in amphibians . In humans , the primary muscle that drives breathing is the diaphragm . The lungs also provide airflow that makes vocal sounds including ___MASK91___ speech possible . The superclass ___MASK25___ ( 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 . Lungfish ( also known as salamanderfish ) are freshwater fish belonging to the subclass ___MASK73___ . Lungfish are best known for retaining characteristics primitive within the Osteichthyes , including the ability to breathe air , and structures primitive within Sarcopterygii , including the presence of lobed fins with a well - developed internal skeleton . Undina is a genus of prehistoric coelacanth , lobe - finned fish , an intermediary form between sea and land animals which lived during the Late Jurassic period .