Multituberculata is an extinct order of rodent-like mammals with a fossil record spanning over 130 million years. They first appeared in the Middle Jurassic, and reached a peak diversity during the Late Cretaceous and Paleocene. They eventually declined from the mid-Paleocene onwards, disappearing from the known fossil record in the late Eocene. They are the most diverse order of Mesozoic mammals with more than 200 species known, ranging from mouse-sized to beaver-sized. These species occupied a diversity of ecological niches, ranging from burrow-dwelling to squirrel-like arborealism to jerboa-like hoppers. Multituberculates are usually placed as crown mammals outside either of the two main groups of living mammals—Theria, including placentals and marsupials, and Monotremata—but usually as closer to Theria than to monotremes. They are considered to be closely related to Euharamiyida and Gondwanatheria as part of Allotheria.
Volaticotherium antiquum is an extinct, gliding, insectivorous mammal that lived in Asia during the Jurassic period, around 164 mya. It is the only member of the genus Volaticotherium.
Volaticotherini is a clade of eutriconodont mammals from the Mesozoic. In addition to the type genus Volaticotherium, it includes the genera Argentoconodon, Ichthyoconodon, and potentially Triconolestes.
Eutriconodonta is an order of early mammals. Eutriconodonts existed in Asia, Africa, Europe, North and South America during the Jurassic and the Cretaceous periods. The order was named by Kermack et al. in 1973 as a replacement name for the paraphyletic Triconodonta.
Pseudotribos is an extinct genus of mammaliaform that lived in Northern China during the Middle Jurassic some 165 million years ago, possibly more closely related to monotremes than to theria, although other studies indicate that these shuotheres are closer to therians than to monotremes. The only known specimen was found in the Daohugou Bed in Inner Mongolia.
Gobiconodon is an extinct genus of carnivorous mammals belonging to the family Gobiconodontidae. Undisputed records of Gobiconodon are restricted to the Early Cretaceous of Asia and North America, but isolated teeth attributed to the genus have also been described from formations in England and Morocco dating as far back as the Middle Jurassic. Species of Gobiconodon varied considerably in size, with G. ostromi, one of the larger species, being around the size of a modern Virginia opossum. Like other gobiconodontids, it possessed several speciations towards carnivory, such as shearing molariform teeth, large canine-like incisors and powerful jaw and forelimb musculature, indicating that it probably fed on vertebrate prey. Unusually among predatory mammals and other eutriconodonts, the lower canines were vestigial, with the first lower incisor pair having become massive and canine-like. Like the larger Repenomamus there might be some evidence of scavenging.
Dryolestida is an extinct order of mammals, known from the Jurassic and Cretaceous. They are considered basal members of the clade Cladotheria, close to the ancestry of therian mammals. It is also believed that they developed a fully mammalian jaw and also had the three middle ear bones. Most members of the group, as with most Mesozoic mammals, are only known from fragmentary tooth and jaw remains.
Shuotheriidae is a small family of Jurassic mammaliaforms whose remains are found in China, England and possibly Russia. They have been proposed to be close relatives of Australosphenida, together forming the clade Yinotheria. However, some studies suggest shuotheres are closer to therians than to monotremes, or that australosphenidans and therians are more closely related to each other than either are to shuotheres, with a 2024 study suggesting that shuotheriids were closely related to Docodonta outside of the Mammalia crown group.
Henosferidae is an extinct family of Australosphenida, native to Gondwana during the Early-Middle Jurassic. It is defined as a clade including the most recent common ancestor of Henosferus and Asfaltomylos and all its descendants.
Triconolestes is an extinct genus of Late Jurassic eutriconodont mammal from the Morrison Formation, present in stratigraphic zones 4. Known from only a single molar, it is a small mammal typically considered an amphilestid. However, it has also been compared to Argentoconodon, which has been considered a volaticothere related to gliding mammals such as Volaticotherium and Ichthyoconodon.
Triconodontidae is an extinct family of small, carnivorous mammals belonging to the order Eutriconodonta, endemic to what would become Asia, Europe, North America and probably also Africa and South America during the Jurassic through Cretaceous periods at least from 190–66 mya.
The Amphidontidae are a family of extinct mammals from the Early Cretaceous, belonging to the eutriconodonts. It contains most of the species previously belonged to Amphilestidae.
Drescheratherium is an extinct genus of mammal from the Late Jurassic (Kimmeridgian) Camadas de Guimarota of Leiria, Portugal. It is represented by fairly complete upper jaws with teeth. It bears elongated upper canines, though not to the extent another dryolestoid, Cronopio, does.
Cronopio is an extinct genus of small insectivorous mammal known from the early Late Cretaceous of the Río Negro region in Argentina. Its only species is Cronopio dentiacutus. It belongs to the Meridiolestida, an extinct group of mammals widespread in South America during the Late Cretaceous, which are more closely related to modern marsupials and placental mammals than to monotremes.
Argentoconodon is an extinct genus of theriimorph mammal from the Cañadón Asfalto Formation of the Cañadón Asfalto Basin in Patagonia. When originally described, it was known only from a single molariform tooth, which possessed a combination of primitive and derived features. The tooth is currently held in the Museo Paleontológico Egidio Feruglio, where it was given the specimen number MPEF-PV 1877. New material described in 2011 show that Argentoconodon was similar to Ichthyoconodon, Jugulator and Volaticotherium within the family Triconodontidae, and possibly also Triconolestes.
Ichthyoconodon is an extinct genus of eutriconodont mammal from the Lower Cretaceous of Morocco. It is notable for having been found in a unique marine location, and the shape of its teeth suggests an unusual, potentially fish-eating ecological niche. Analysis suggests it is part of a group of gliding mammals that includes Volaticotherium.
Jugulator is an extinct genus of mammals from the Cretaceous of North America. It contains one species, Jugulator amplissimus. A eutriconodont, it is known from the Cedar Mountain Formation, and is both a large sized and possibly ecologically specialised taxon, showcasing the diversity of mammals in the Mesozoic.
Meridiolestida is an extinct clade of mammals known from the Cretaceous and Cenozoic of South America and possibly Antarctica. They represented the dominant group of mammals in South America during the Late Cretaceous. Meridiolestidans were morphologically diverse, containing both small insectivores such as the "sabretooth-squirrel" Cronopio, as well as the clade Mesungulatoidea/Mesungulatomorpha, which ranged in size from the shrew-sized Reigitherium to the dog-sized Peligrotherium. Mesungulatoideans had highly modified dentition with bunodont teeth, and were likely herbivores/omnivores. Meridiolestidans are generally classified within Cladotheria, more closely related to living marsupials and placental mammals (Theria) than to monotremes, barring one study recovering them as the sister taxa to spalacotheriid "symmetrodonts". However, more recent studies have stuck to the cladotherian interpretation. Within Cladotheria, they have often been placed in a group called Dryolestoidea together with Dryolestida, a group of mammals primarily known from the Jurassic and Early Cretaceous of the Northern Hemisphere. However, some analyses have found this group to be paraphyletic, with the meridiolestidans being more or less closely related to therian mammals than dryolestidans are. Meridiolestidans differ from dryolestidans in the absence of a parastylar hook on the molariform teeth and the lack of a Meckelian groove.
Condorodon is a genus of extinct mammals from the Lower Jurassic Cañadón Asfalto Formation of the Cañadón Asfalto Basin in Patagonia, Argentina. The type species is C. spanios, described by Gaetano and Rougier in 2012.
Zhelestidae is a lineage of extinct eutherian mammals. Occurring in the Late Cretaceous from the Turonian to the Maastrichtian, they were an extremely successful group, with representatives present in Europe, Asia, India, Africa and North America, ostensibly rendering them a cosmopolitan clade. They were specialised towards an herbivorous lifestyle and were in fact initially considered stem-ungulates, but the presence of epipubics and "archaic" dental characters render them as non-placental eutherians.
