? Mammaliaformes Fossil range: Late Triassic to Recent
Castorocauda a non-mammalian mammaliaform
Scientific classification
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata (unranked) Amniota (unranked) Synapsida (unranked) Mammaliaformes Rowe, 1988
Clades
Allotheria Adelobasileus Sinoconodon Morganucodonta Megazostrodontidae Docodonta Hadrocodium Kuehneotheriidae Symmetrodonta Mammalia

Mammaliaformes is a clade that contains the mammals and their closest extinct relatives. The precise phylogeny is disputed due to the scantness of evidence in the fossil record. However, it is thought that the Mammaliaformes were of three major groups: Allotheria, the longest extinct lineage of pre-mammals; Docodonta, including close relatives such as Morganucodonta; and Symmetrodonta, the most basal of modern mammals. Mammaliaformes radiated from Cynodontia. The Triassic is a geologic period that extends from about 245 to 202 Ma (million years ago). ... Image File history File links CastorocaudaLutrasimilis. ... Binomial name Castorocauda lutrasimilis Ji, Luo, Yuan, Tabrum, 2006 Castorocauda lutrasimilis is the name given to a small, semi-aquatic relative of mammals living in the middle Jurassic period, 164 million years ago, in lakebed sediments of the Jiulongshan formation of Inner Mongolia. ... Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms. ... Binomial name Aptenodytes forsteri Gray, 1844 For other uses, see Animal (disambiguation). ... Typical Classes Subphylum Urochordata - Tunicatas Ascidiacea Thaliacea Larvacea Subphylum Cephalochordata - Lancelets Subphylum Myxini - Hagfishes Subphylum Vertebrata - Vertebrates Petromyzontida - Lampreys Placodermi (extinct) Chondrichthyes - Cartilaginous fishes Acanthodii (extinct) Actinopterygii - Ray-finned fishes Actinistia - Coelacanths Dipnoi - Lungfishes Amphibia - Amphibians Reptilia - Reptiles Aves - Birds Mammalia - Mammals Chordates (phylum Chordata) include the vertebrates, together with... Typical classes Petromyzontidae (lampreys) Placodermi - extinct Chondrichthyes (cartilaginous fish) Acanthodii - extinct Actinopterygii (ray-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Amphibia (amphibians) Reptilia (reptiles) Aves (birds) Mammalia (mammals) Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ... Extant subgroups Synapsida     Mammalia (mammals) Sauropsida    Anapsida        Testudines (turtles)    Diapsida        Lepidosauria           Squamata (lizards and snakes)           Sphenodontida (tuatara)        Archosauria           Crocodilia (crocodiles and alligators)           Aves (birds) The amniotes are a group of vertebrates, comprising the mammals, birds, and various other groups collectively referred to as reptiles. ... Groups Caseasauria Eupelycosauria    Sphenacodontia       Therapsida          (...mammals) Synapsids (fused arch), formerly known as mammal-like reptiles, are a group of amniotes (reptiles and all their ancestors) that developed one hole in their skull (temporal fenestra) behind each eye, about 320 million years ago (Ma) during the late Carboniferous. ... A clade is group of organisms which share a common ancestor and which includes all decendents of that ancestor. ... Suborders   Plagiaulacida   Cimolodonta The Multituberculata are the only major branch of mammals to have become completely extinct, with no living descendants. ... Binomial name Adelobasileus cromptoni Lucas & Hunt, 1990 Adelobasileus cromptoni is a species of an extinct genus of proto-mammals from the middle Triassic, about 225 million years ago. ... Sinoconodon is an ancient proto-mammal that appears in the fossil record in the early Jurassic period, about 208 million years ago. ... The megazostrodon is widely accepted as the first mammal. ... Docodonta is an order of extinct mammals that lived during the mid- to late-Mesozoic era. ... Hadrocodium is a mammal species which lived during the Lower Jurassic in present-day China. ... Symmetrodonta is a basal group of Mesozoic mammals characterized by the triangular aspect of the molars when viewed from above and the absence of a well−developed talonid. ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... A clade is group of organisms which share a common ancestor and which includes all decendents of that ancestor. ... Orders Subclass Multituberculata (extinct) Plagiaulacida Cimolodonta Subclass Palaeoryctoides (extinct) Subclass Triconodonta (extinct) Subclass Eutheria (includes extinct ancestors)/Placentalia (excludes extinct ancestors) Afrosoricida Artiodactyla Carnivora Cetacea Chiroptera Cimolesta (extinct) Creodonta (extinct) Condylarthra (extinct) Dermoptera Desmostylia (extinct) Embrithopoda (extinct) Hyracoidea Insectivora Lagomorpha Litopterna (extinct) Macroscelidea Mesonychia (extinct) Notoungulata (extinct) Perissodactyla Pholidota Plesiadapiformes... In biology and ecology, extinction is the ceasing of existence of a species or group of taxa. ... In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e. ... Ever since recorded history began, and probably before, people have found pieces of rock and other hard material with indentations from the remains of dead organisms. ... Suborders   Plagiaulacida   Cimolodonta The Multituberculata are the only major branch of mammals to have become completely extinct, with no living descendants. ... Docodonta is an order of extinct mammals that lived during the mid- to late-Mesozoic era. ... Symmetrodonta is a basal group of Mesozoic mammals characterized by the triangular aspect of the molars when viewed from above and the absence of a well−developed talonid. ... In phylogenetics, basal members of a group are subgroups that diverged very early from the others. ... Adaptive radiation describes the rapid speciation of a single or a few species to fill many ecological niches. ... Clades Procynosuchidae Epicynodontia Galesauridae Eucynodontia Cynognathia Cynognathidae Tritylodontidae Probainognathia Trithelodontidae Mammaliformes Cynodonta is the suborder that contains the most mammal-like of the non-mammalian therapsids, which are sometimes termed mammal-like reptiles. The most derived cynodonts are found within Eucynodontia clade, which also contains the members of Mammalia. ...

Early mammaliforms were generally rodent-like in appearance and size, and most of their distinguishing characteristics were internal. In particular, the structure of the mammaliform (and mammal) jaw and arrangment of teeth is nearly unique. Instead of having many teeth that are frequently replaced, mammals have one set of adult teeth which fit together precisely. Mammaliforms seem to have been structured similarly. Most importantly, mammaliforms have highly specialized molars, with cusps and flat regions for grinding food. This system is also unique to mammals, although it seems to have evolved convergently in pre-mammals multiple times. Families See Classification Section The order Rodentia is the most numerous of all the branches on the mammal family tree. ... The jaw is either of the two opposable structures forming, or near the entrance to, the mouth. ... Types of teeth Molars are used for grinding up foods Carnassials are used for slicing food. ... Molar 47 (left), molar 46 and premolar 45(right) Molars are the rearmost and most complicated kind of tooth in most mammals. ... In common parlance, a cusp is an important moment usually regarded as a decision point upon which consequent events are determined. ... In evolutionary biology, convergent evolution describes the process whereby organisms not closely related independently acquire similar characteristics while evolving in separate and sometimes varying ecosystems. ...

Lactation and fur, along with other characteristically mammalian features, are also thought to characterize the Mammaliaformes, but these traits are difficult to study in the fossil record. The fossilized remains of Castorocauda lutrasimilis are an unique exception. Lactation describes the secretion of milk from the mammary glands, the process of providing that milk to the young, and the period of time that a mother lactates to feed her young. ... A dogs fur usually consists of longer, stiffer, guard hairs—which can be straight, wiry, or wavy, and of various lengths, hiding a soft, short-haired undercoat. ... Binomial name Castorocauda lutrasimilis Ji, Luo, Yuan, Tabrum, 2006 Castorocauda lutrasimilis is the name given to a small, semi-aquatic relative of mammals living in the middle Jurassic period, 164 million years ago, in lakebed sediments of the Jiulongshan formation of Inner Mongolia. ...

External links

• Mammaliforms and Mammaliaformes from Palaeos
• Mesozoic Mammals; Basal Mammaliaformes, an internet directory