parent_taxon eolagurus
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 ___MASK25___ form the ___MASK50___ clade . The mammals consist of the Yinotheria including monotrema and the Theriiformes including the theria . The ___MASK89___ are a large superfamily of rodents , including mice , rats , voles , hamsters , gerbils , and many other relatives . They occupy a vast variety of habitats on every continent except Antarctica . Some authorities have placed all members of this group into a single family , ___MASK41___ , due to difficulties in determining how the subfamilies are related to one another . The following taxonomy is based on recent well - supported molecular phylogenies . Eolagurus is a genus of rodent in the family ___MASK60___ . It contains the following species : Yellow Steppe Lemming ( Eolagurus luteus ) Przewalski ' s Steppe Lemming ( Eolagurus przewalskii ) A lemming is a small rodent , usually found in or near the Arctic , in tundra biomes . Lemmings are subniveal animals and together with voles and muskrats , they make up the subfamily ___MASK91___ ( also known as Microtinae ), which forms part of the largest mammal radiation by far , the superfamily Muroidea , which also includes rats , mice , hamsters , and gerbils . Rodents ( from Latin " rodere ", " to gnaw ") are mammals of the order ___MASK22___ , which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws . About 40 % of all mammal species are rodents ; they are found in vast numbers on all continents except Antarctica . They are the most diversified mammalian order and live in a variety of terrestrial habitats , including human - made environments . Hamsters are rodents belonging to the subfamily ___MASK35___ . The subfamily contains about 25 species , classified in six or seven genera . They have become established as popular small house pets , and partly because they are easy to breed in captivity , hamsters are often used as laboratory animals . The ___MASK60___ are a family of rodents in the large and complex superfamily Muroidea . It includes true hamsters , voles , lemmings , and New World rats and mice . At almost 600 species , it is the second - largest family of mammals , and has members throughout the Americas , Asia , and Europe . The New World rats and mice are a group of related rodents found in North and South America . They are extremely diverse in appearance and ecology , ranging in from the tiny " ___MASK5___ " to the large " ___MASK78___ ". They represent one of the few examples of muroid rodents ( along with the voles ) in North America , and the only example of muroid rodents to have made it into South America . A vole is a small rodent ; a relative of the mouse , with a stouter body , a shorter , hairy tail , a slightly rounder head , smaller ears and eyes , and differently formed molars ( high - crowned and with angular cusps instead of low - crowned and with rounded cusps ). There are approximately 155 species of voles . They are sometimes known as meadow mice or field mice in North America and Australia . Vole species form the subfamily ___MASK91___ with the lemmings and the muskrats . A habitat is an ecological or environmental ___MASK47___ that is inhabited by a particular species of animal , ___MASK15___ , or other type of organism . The term typically refers to the zone in which the organism lives and where it can find food , shelter , protection and mates for reproduction . It is the natural environment in which an organism lives , or the physical environment that surrounds a species population .