The lagomorphs are the members of the taxonomic order Lagomorpha, of which there are two living families: the Leporidae and the Ochotonidae (pikas). There are 110 recent species of lagomorph of which 109 are extant, including 10 genera of rabbits, 1 genus of hare and 1 genus of pika. The name of the order is derived from the Ancient Greek lagos + morphē.
Placental mammals are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguished from monotremes and marsupials in that the fetus is carried in the uterus of its mother to a relatively late stage of development. The name is something of a misnomer considering that marsupials also nourish their fetuses via a placenta, though for a relatively briefer period, giving birth to less developed young which are then nurtured for a period inside the mother's pouch. Placentalia represents the only living group within Eutheria, which contains all mammals more closely related to placentals than to marsupials.
Taeniolabidoidea is a group of extinct mammals known whose fossils can be found in North America and Asia. They were the largest members of the extinct order Multituberculata, as well as the largest non-therian mammals. Lambdopsalis even provides direct fossil evidence of mammalian fur in a fairly good state of preservation for a 60-million-year-old animal. Some of these animals were large for their time; Taeniolabis taoensis is the largest known multituberculate and though smaller, Yubaatar is the largest known Mesozoic Asian multituberculate. T. taoensis averaged a body mass of 22.7 kilograms (50 lb).
Glires is a clade consisting of rodents and lagomorphs. The hypothesis that these form a monophyletic group has been long debated based on morphological evidence. Two morphological studies, published in 2001 and 2003, strongly support the monophyly of Glires. In particular, the 2003 study reported the discovery of fossil material of basal members of Glires, particularly the genera Mimotona, Gomphos, Heomys, Matutinia, Rhombomylus, and Sinomylus. Their description, in 2005, helped to bridge the gap between more typical rodents and lagomorphs. Data published in 2001, based on nuclear DNA, supported Glires as a sister of Euarchonta to form Euarchontoglires, but some genetic data from both nuclear and mitochondrial DNA have been less supportive. A study, published in 2007, investigating retrotransposon presence/absence data unambiguously supports the Glires hypothesis. Studies published in 2011 and 2015 place Scandentia as a sister clade of the Glires, invalidating Euarchonta as a clade.
Mammalia is a class of animal within the phylum Chordata. Mammal classification has been through several iterations since Carl Linnaeus initially defined the class. No classification system is universally accepted; McKenna & Bell (1997) and Wilson & Reader (2005) provide useful recent compendiums. Many earlier ideas from Linnaeus et al. have been completely abandoned by modern taxonomists, among these are the idea that bats are related to birds or that humans represent a group outside of other living things. Competing ideas about the relationships of mammal orders do persist and are currently in development. Most significantly in recent years, cladistic thinking has led to an effort to ensure that all taxonomic designations represent monophyletic groups. The field has also seen a recent surge in interest and modification due to the results of molecular phylogenetics.
Ferae is a mirorder of placental mammals from grandorder Ferungulata, that groups together clades Pan-Carnivora, which includes modern carnivorans, and Pholidotamorpha, which includes pangolins.
Cimolesta is an extinct order of non-placental eutherian mammals. Cimolestans had a wide variety of body shapes, dentition and lifestyles, though the majority of them were small to medium-sized general mammals that bore superficial resemblances to rodents, lagomorphs, mustelids, and marsupials.
Eomyidae is a family of extinct rodents from North America and Eurasia related to modern day pocket gophers and kangaroo rats. They are known from the Middle Eocene to the Late Miocene in North America and from the Late Eocene to the Pleistocene in Eurasia. Eomyids were generally small, but occasionally large, and tended to be squirrel-like in form and habits. The family includes the earliest known gliding rodent, Eomys quercyi.
Eurymylidae is a family of extinct simplicidentates. Most authorities consider them to be basal to all modern rodents and may have been the ancestral stock whence the most recent common ancestor of all modern rodents arose. However, the more completely known eurymylids, including Eurymylus, Heomys, Matutinia, and Rhombomylus, appear to represent a monophyletic side branch not directly ancestral to rodents. Huang et al. (2004) have argued that Hanomys, Matutinia, and Rhombomylus form a clade characterized by distinctive features of the skull and dentition that should be recognized as a separate family, Rhombomylidae. Eurymylids are only known from Asia.
The Tsaganomyidae are an extinct family of rodents from Asia. It contains three genera. Tsaganomyids are generally considered to be related to the Hystricognathi. Members of Tsaganomyidae were fossorial (digging) rodents that probably used their incisor teeth to dig like some living mole rats.
Alagomyidae is a family of rodents known from the late Paleocene and early Eocene of Asia and North America. Alagomyids have been identified as the most basal rodents, lying outside the common ancestry of living forms. Because of their phylogenetic position and their conservative dental morphology, alagomyids have played a key role in investigations of the origins and relationships of rodents.
Mesotheriidae is an extinct family of notoungulate mammals known from the Oligocene through the Pleistocene of South America. Mesotheriids were small to medium-sized herbivorous mammals adapted for digging.
Gomphos is an extinct genus of early lagomorph from the early Eocene of the China and Mongolia.
Anagaloidea is a former order of extinct placental mammals that first appeared during the Paleocene epoch.
The Irdin Manha Formation is a geological formation from the Eocene located in Inner Mongolia, China, a few kilometres south of the Mongolian border.
Hunter-Schreger bands, commonly abbreviated as HSB, are features of the enamel of the teeth in mammals, mostly placentals. In HSB, enamel prisms are arranged in layers of varying thickness at about right angles to each other. HSB strengthen the enamel and prevent cracks from propagating through the tooth.
Preptotheria is a superorder of placental mammals proposed by McKenna & Bell in their classification of mammals.
Groeberiidae is a family of strange non-placental mammals from the Eocene and Oligocene epochs of Patagonia, Argentina and Chile, South America. Originally classified as paucituberculate marsupials, they were suggested to be late representatives of the allothere clade Gondwanatheria. However, the relationship of the type genus, Groeberia, to Gondwanatheria has been firmly rejected by other scholars.
Viverravus is an extinct genus of placental mammals from extinct subfamily Viverravinae within extinct family Viverravidae, that lived in North America, Europe and Asia from the middle Paleocene to middle Eocene.
Pseudictopidae is an extinct family of mammals closely related to rodents and lagomorphs. Members of the family are known from Paleocene to Eocene deposits in China and Mongolia.
