With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Mammals are within a class.
text_B: Mammals are any vertebrates within the class Mammalia -LRB- -LSB- məˈmeɪli.ə -RSB- from Latin mamma #Latin `` breast '' -RRB- , a clade of endothermic amniotes distinguished from reptiles -LRB- including birds -RRB- by the possession of a neocortex -LRB- a region of the brain -RRB- , hair , three middle ear bones and mammary glands .. class. class ( biology ). Latin. Latin language. clade. clade. neocortex. neocortex. hair. hair. middle ear bones. ossicles. Females of all mammal species nurse their young with milk , secreted from the mammary glands .. Females. Female#Mammalian female. milk. milk. species. species. Mammals include the biggest animals on the planet , the great whales .. great whales. baleen whale. The basic body type is a terrestrial quadruped , but some mammals are adapted for life at sea , in the air , in trees , underground or on two legs .. quadruped. quadruped. life at sea. marine mammal. the air. aerial locomotion. in trees. arboreal locomotion. underground. fossorial. on two legs. biped. The largest group of mammals , the placentals , have a placenta , which enables the feeding of the fetus during gestation .. placentals. placentals. placenta. placenta. Mammals range in size from the 30 -- bumblebee bat to the 30 m blue whale .. bumblebee bat. bumblebee bat. blue whale. blue whale. whale. whale. With the exception of the five species of monotreme -LRB- egg-laying mammals -RRB- , all modern mammals give birth to live young .. species. species. monotreme. monotreme. Most mammals , including the six most species-rich orders , belong to the placental group .. species. species. orders. order ( biology ). The largest orders are the rodents , bats and Soricomorpha -LRB- shrews and allies -RRB- .. orders. order ( biology ). rodents. rodents. bats. bats. Soricomorpha. Soricomorpha. The next three biggest orders , depending on the biological classification scheme used , are the Primates -LRB- apes and monkeys -RRB- , the Cetartiodactyla -LRB- whales and even-toed ungulates -RRB- , and the Carnivora -LRB- cats , dogs , seals , and allies -RRB- .. orders. order ( biology ). biological classification. biological classification. Cetartiodactyla. Cetartiodactyla. Carnivora. Carnivora. seals. pinniped. Living mammals are divided into the Yinotheria -LRB- platypus and echidnas -RRB- and Theriiformes -LRB- all other mammals -RRB- .. Yinotheria. Yinotheria. Theriiformes. Theriiformes. platypus. platypus. There are around 5450 species of mammal , depending on which authority is cited .. species. species. In some classifications , extant mammals are divided into two subclasses  : the Prototheria , that is , the order Monotremata ; and the Theria , or the infraclasses Metatheria and Eutheria .. Monotremata. Monotreme. Theria. Theria. Prototheria. Prototheria. Metatheria. Metatheria. Eutheria. Eutheria. The marsupials constitute the crown group of the Metatheria , and include all living metatherians as well as many extinct ones ; the placentals are the crown group of the Eutheria .. placentals. placentals. Metatheria. Metatheria. Eutheria. Eutheria. crown group. crown group. While mammal classification at the family level has been relatively stable , several contending classifications regarding the higher levels -- subclass , infraclass and order , especially of the marsupials -- appear in contemporaneous literature .. mammal classification. mammal classification. Much of the changes reflect the advances of cladistic analysis and molecular genetics .. cladistic analysis. cladistic analysis. molecular genetics. molecular genetics. Findings from molecular genetics , for example , have prompted adopting new groups , such as the Afrotheria , and abandoning traditional groups , such as the Insectivora .. molecular genetics. molecular genetics. Afrotheria. Afrotheria. Insectivora. Insectivora. The mammals represent the only living Synapsida , which together with the Sauropsida form the Amniota clade .. clade. clade. Sauropsida. Sauropsida. Amniota. Amniota. The early synapsid mammalian ancestors were sphenacodont pelycosaurs , a group that produced the non-mammalian Dimetrodon .. sphenacodont. Sphenacodontia. Dimetrodon. Dimetrodon. At the end of the Carboniferous period , this group diverged from the sauropsid line that led to today 's reptiles and birds .. Carboniferous. Carboniferous. The line following the stem group Sphenacodontia split-off several diverse groups of non-mammalian synapsids -- sometimes referred to as mammal-like reptiles -- before giving rise to the proto-mammals -LRB- Therapsida -RRB- in the early Mesozoic era .. the proto-mammals. Dimetrodon#Clade Synapsida. Therapsida. Therapsida. Mesozoic. Mesozoic. The modern mammalian orders arose in the Paleogene and Neogene periods of the Cenozoic era , after the extinction of non-avian dinosaurs , and have been among the dominant terrestrial animal groups from 66 million years ago to the present .. orders. order ( biology ). Paleogene. Paleogene. Neogene. Neogene. Cenozoic. Cenozoic. extinction of non-avian dinosaurs. Cretaceous–Paleogene extinction event. Some mammals are intelligent , with some possessing large brains , self-awareness and tool use .. intelligent. animal cognition. self-awareness. self-awareness. tool use. tool use in animals. Mammals can communicate and vocalize in several different ways , including the production of ultrasound , scent-marking , alarm signals , singing , and echolocation .. ultrasound. ultrasound. scent-marking. scent-marking. singing. Singing#Singing animals. echolocation. Animal echolocation. Mammals can organize themselves into fission-fusion societies , harems , and hierarchies , but can also be solitary and territorial .. fission-fusion societies. fission-fusion society. harems. harem ( zoology ). hierarchies. hierarchy. territorial. Territory ( animal ). Most mammals are polygynous , but some can be monogamous or polyandrous .. polygynous. polygyny in animals. monogamous. monogamy in animals. polyandrous. Polyandry in nature. In human culture , domesticated mammals played a major role in the Neolithic revolution , causing farming to replace hunting and gathering , and leading to a major restructuring of human societies with the first civilizations .. domesticated. domestication. Neolithic revolution. Neolithic revolution. farming. agriculture. hunting and gathering. hunter-gatherer. They provided , and continue to provide , power for transport and agriculture , as well as various commodities such as meat , dairy products , wool , and leather .. meat. meat. wool. wool. leather. leather. Mammals are hunted or raced for sport , and are used as model organisms in science .. hunted. hunting. Mammals have been depicted in art since Palaeolithic times , and appear in literature , film , mythology , and religion .. art. art. Palaeolithic. Palaeolithic. Defaunation of mammals is primarily driven by anthropogenic factors , such as poaching and habitat destruction , though there are efforts to combat this .. Defaunation. Defaunation. anthropogenic. Holocene extinction. poaching. poaching. habitat destruction. habitat destruction
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