Hahnodon is an extinct genus of mammaliaforms from the Early Cretaceous Ksar Metlili Formation in Morocco. Although originally considered to be a relatively early member of the extinct clade Multituberculata, recent studies indicate that it instead is a haramiyid.
Morganucodon is an early mammaliaform genus that lived from the Late Triassic to the Middle Jurassic. It first appeared about 205 million years ago. Unlike many other early mammaliaforms, Morganucodon is well represented by abundant and well preserved material. Most of this comes from Glamorgan in Wales, but fossils have also been found in Yunnan Province in China and various parts of Europe and North America. Some closely related animals (Megazostrodon) are known from exquisite fossils from South Africa.
Hahnodontidae is a family of extinct mammaliaforms from Early Cretaceous deposits in Morocco and the Western United States. Although originally considered to belong to the extinct clade Multituberculata, recent work indicates that hahnodontids belong to the more primitive clade Haramiyida.
Docodonta is an order of extinct Mesozoic mammaliaforms. They were among the most common mammaliaforms of their time, persisting from the Middle Jurassic to the Early Cretaceous across the continent of Laurasia. They are distinguished from other early mammaliaforms by their relatively complex molar teeth. Docodont teeth have been described as "pseudotribosphenic": a cusp on the inner half of the upper molar grinds into a basin on the front half of the lower molar, like a mortar-and-pestle. This is a case of convergent evolution with the tribosphenic teeth of therian mammals. There is much uncertainty for how docodont teeth developed from their simpler ancestors. Their closest relatives may have been certain Triassic "symmetrodonts", namely Woutersia, Delsatia, and Tikitherium.
Haramiyida is a possibly polyphyletic order of mammaliaform cynodonts or mammals of controversial taxonomic affinites. Their teeth, which are by far the most common remains, resemble those of the multituberculates. However, based on Haramiyavia, the jaw is less derived; and at the level of evolution of earlier basal mammals like Morganucodon and Kuehneotherium, with a groove for ear ossicles on the dentary. Some authors have placed them in a clade with Multituberculata dubbed Allotheria within Mammalia. Other studies have disputed this and suggested the Haramiyida were not crown mammals, but were part of an earlier offshoot of mammaliaformes instead. It is also disputed whether the Late Triassic species are closely related to the Jurassic and Cretaceous members belonging to Euharamiyida/Eleutherodontida, as some phylogenetic studies recover the two groups as unrelated, recovering the Triassic haramiyidians as non-mammalian cynodonts, while recovering the Euharamiyida as crown-group mammals closely related to multituberculates.
Trechnotheria is a group of mammals that includes the therians and some fossil mammals from the Mesozoic Era. It includes both the extinct symmetrodonts and the living Cladotheria.
Kuehneotherium is an early mammaliaform genus, previously considered a holothere, that lived during the Late Triassic-Early Jurassic Epochs and is characterized by reversed-triangle pattern of molar cusps. Although many fossils have been found, the fossils are limited to teeth, dental fragments, and mandible fragments. The genus includes Kuehneotherium praecursoris and all related species. It was first named and described by Doris M. Kermack, K. A. Kermack, and Frances Mussett in November 1967. The family Kuehneotheriidae and the genus Kuehneotherium were created to house the single species Kuehneotherium praecursoris. Modeling based upon a comparison of the Kuehneotherium jaw with other mammaliaforms indicates it was about the size of a modern-day shrew between 4 and 5.5 g at adulthood.
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.
Purbeckodon is an extinct genus of mammaliaforms, possibly belonging to Morganucodonta, that is known from Early Cretaceous deposits of southeastern Dorset, England. It was collected in the Purbeck Limestone Group of Dorset. It was first named by Percy M. Butler, Denise Sigogneau-Russell and P. C. Ensom in 2011 and the type species is Purbeckodon batei.
Euharamiyida also known as Eleutherodontida, is clade of early mammals or mammal-like cynodonts from the Middle Jurassic to Early Cretaceous of Eurasia and possibly North America. The group is sometimes considered a sister group to Multituberculata, or part of an earlier divergence within the synapsid line. It is disputed whether or not they are related to the Haramiyids from the Late Triassic, such as Haramiyavia. The morphology of their teeth indicates that they were herbivorous or omnivorous. Some members of the group are known to be arboreal, including gliding forms similar to modern flying squirrels or colugos.
Wareolestes rex is a mammaliaform from the Middle Jurassic (Bathonian) rocks of England and Scotland. It was originally known from isolated teeth from England, before a more complete jaw with teeth was found in the Kilmaluag Formation of Skye, Scotland.
Vilevolodon is an extinct, monotypic genus of volant, arboreal euharamiyids from the Oxfordian age of the Late Jurassic of China. The type species is Vilevolodon diplomylos. The genus name Vilevolodon references its gliding capabilities, Vilevol, while don is a common suffix for mammalian taxon titles. The species name diplomylos refers to the dual mortar-and-pestle occlusion of upper and lower molars observed in the holotype; diplo, mylos.
Peraiocynodon is an extinct mammaliaform from the order Docodonta, found in the Middle Jurassic rocks of the United Kingdom. It is only known from isolated molar teeth found in the mammal bed at Kirtlington cement quarry in Oxfordshire, England.
Cyrtlatherium is a dubious genus of extinct docodontan mammaliaform from the Middle Jurassic rocks of Oxfordshire, England. As it is only known from a few isolated molar teeth, there is disagreement about whether Cyrtlatherium is a separate genus, or whether it is a synonym and the molar teeth are the milk teeth of another genus of docodont.
Denise Sigogneau-Russell is a French palaeontologist who specialises in mammals from the Mesozoic, particularly from France and the UK. She is currently based at the Muséum National d'Histoire Naturelle.
Dromatheriidae is an extinct family of prozostrodontian cynodonts, closely related to mammals. Members of the family are known from the Late Triassic of India, Europe and North America. Apart from a few jaw fragments, dromatheriids are mainly known from their sectorial (flesh-slicing) postcanine teeth. The teeth were fairly typical among early prozostrodontians, as they were labiolingually compressed, with a single root and crown hosting a longitudinal row of sharp cusps. Dromatheriids in particular have a very narrow and symmetrical crown without a prominent cingulum.
Rhomphaiodon is an extinct genus of prehistoric sharks in the order Synechodontiformes that has been found in Late Triassic and Early Jurassic deposits located in Europe. The type species R. minor was originally named as a species of Hybodus in 1837 by Louis Agassiz. A second species, R. nicolensis, was added when the genus was named in 1993.
Cherwellia is an extinct genus of mammaliaforms, possibly belonging to Morganucodonta, that lived in what is now England during the Middle Jurassic. The type and only known species is Cherwellia leei. It was first described in 2016 by Percy M. Butler and Denise Sigogneau-Russell from a single lower molar found at the Kirtlington Quarry of the Forest Marble Formation.
Stylidens is an extinct genus of mammaliaforms, possibly belonging to Morganucodonta, that lived in what is now England during the Middle Jurassic. Its type species is Stylidens hookeri, which was named in 2016 by Percy M. Butler and Denise Sigogneau-Russell from an isolated lower molar found at the Forest Marble Formation. A second molar referable to the genus is also known, which may represent a separate species.
Dobunnodon its an extinct genus of docodont from the Middle Jurassic (Bathonian) Forest Marble Formation of England, first discovered in Oxfordshire near the village of Kirtlington. The type species, D. mussettae, was originally named as a species of Borealestes in 2003.
