Multituberculata is an extinct order of rodent-like mammals with a fossil record spanning over 120 million years. They first appeared in the Middle Jurassic, and reached a peak diversity during the Cretaceous. They eventually declined from the late 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 closer to Theria than to monotremes. Nonetheless, at least one study found a potential status as sister taxa to monotremes/Australosphenida.
Plagiaulacida is a group of extinct multituberculate mammals. Multituberculates were among the most common mammals of the Mesozoic, "the age of the dinosaurs". Plagiaulacids, an informal suborder, are the most basal of this order, and ranged from the Middle Jurassic Period to the Lower Cretaceous Period of the northern hemisphere.
Bolodon is a genus of extinct mammal from the Lower Cretaceous of Europe and North America. It was a member of the extinct order of Multituberculata and belongs to the suborder Plagiaulacida and family Plagiaulacidae.
Paracimexomys is a genus of extinct mammals in the also extinct Multituberculata order. Paracimexomys lived during the Cretaceous period. The few fossils remains come from North America. Some Romanian fossils were also tentatively assigned to this genus, though that classification now seems doubtful.
Echinodon is a genus of heterodontosaurid dinosaur that lived during the earliest Cretaceous of southern England and possibly western France in the Berriasian epoch. The first specimens were jaw bones named Echinodon becklesii by Sir Richard Owen in 1861, and since their original description only additional teeth have been discovered. The specific name honours collector Samuel Beckles who discovered the material of Echinodon and many other taxa from across England, while the genus name translates as "prickly tooth" in reference to the dental anatomy of the taxon.
Mantellisaurus is a genus of iguanodontian dinosaur that lived in the Barremian and early Aptian ages of the Early Cretaceous Period of Europe. Its remains are known from Belgium (Bernissart), England, Spain and Germany. The type and only species is M. atherfieldensis. Formerly known as Iguanodon atherfieldensis, the new genus Mantellisaurus was erected for the species by Gregory Paul in 2007. According to Paul, Mantellisaurus was more lightly built than Iguanodon and more closely related to Ouranosaurus, making Iguanodon in its traditional sense paraphyletic. It is known from many complete and almost complete skeletons. The genus name honours Gideon Mantell, the discoverer of Iguanodon.
Suchosaurus is a spinosaurid dinosaur from Cretaceous England and Portugal, originally believed to be a genus of crocodile. The type material, consisting of teeth, was used by British palaeontologist Richard Owen to name the species S. cultridens in 1841. Later in 1897, French palaeontologist Henri-Émile Sauvage named a second species, S. girardi, based on two fragments from the mandible and one tooth discovered in Portugal. Suchosaurus is possibly a senior synonym of the contemporary spinosaurid Baryonyx, but is usually considered a dubious name due to the paucity of its remains. In the Wadhurst Clay Formation of what is now southern England, Suchosaurus lived alongside other dinosaurs, as well as plesiosaurs, mammals, and crocodyliforms.
Haramiyidans were a long lived lineage of mammaliaform cynodonts or mammals. 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. If they are early multituberculates, they would be the longest lived mammalian clade of all time. However, a more recent study, in November 2015, may dispute this and suggested the Haramiyida were not crown mammals, but were part of an earlier offshoot of mammaliaformes instead.
Dryolestida is an extinct order of mammals; most of the members are mostly known from the Jurassic to Paleogene, with one member, Necrolestes, surviving as late as the early Miocene. They are considered 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. Other than that, not much is known about them, this is because their fossils are made up mostly of jaw and tooth remains.
Dryolestidae was a widespread family of Mesozoic mammals. The clade is not based on a phylogenetic definition, but instead on the possession of unequal roots for the molars of the lower jaw. Additionally, the clade is distinguished by hypsodonty in lower molars, and uneven labio-lingual height for the alveolar borders of the dentary.
Amblotherium is an extinct genus of Late Jurassic and Early Cretaceous mammal. The type species Amblotherium pusillum is from the Lulworth Formation of southern England, while the referred species Amblotherium gracile is from stratigraphic zones 2, 3 and 5 of the Morrison Formation of the US.
Dryolestes is an extinct genus of Late Jurassic mammal from the Morrison Formation and the Alcobaça Formation of Portugal. The type species Dryolestes priscus is present in stratigraphic zones 2, 5, and 6.
Triconodontidae is an extinct family of actively mobile mammal, endemic to what would be North America, Europe, Africa and probably also South America and Asia during the Jurassic through Cretaceous periods at least from 190–70.6 mya. They are distinguished from amphilestids and gobiconodontids due to their occlusion patterns: instead of interlocking molars, triconodontids fit their teeth more directly, with lower cusp "a" occluding anteriorly to upper cusp "A", between "A" and "B". However, a study on Priacodon suggests that they had embrasure occlusion.
Acheroraptor is an extinct genus of dromaeosaurid theropod dinosaur known from the latest Maastrichtian Hell Creek Formation of Montana, United States. It contains a single species, Acheroraptor temertyorum. A. temertyorum is one of the two geologically youngest known species of dromaeosaurids, the other being Dakotaraptor, which is also known from Hell Creek. A basal cousin of Velociraptor, Acheroraptor is known from upper and lower jaw material.
Triconodon is a genus of extinct mammal from the Early Cretaceous of England and France with two known species: T. mordax and T. averianovi. First described in 1859 by Richard Owen, it is the type genus for the order Triconodonta, a group of mammals characterised by their three-cusped (triconodont) molar teeth. Since then, this "simplistic" type of dentition has been understood to be either ancestral for mammals or else to have evolved multiple times, rendering "triconodonts" a paraphyletic or polyphyletic assemblage respectively, but several lineages of "triconodont" mammals do form a natural, monophyletic group, known as Eutriconodonta, of which Triconodon is indeed part of.
Leonardus is an extinct mammal genus from the Late Cretaceous of South America. It is a meridiolestidan dryolestoid, closely related to the also Late Cretaceous Cronopio and the Miocene Necrolestes.
Achyrodon is an extinct genus of mammal from the Berriasian epoch of Early Cretaceous southern England. The taxon was first described by Richard Owen in 1871 for teeth from the Lulworth Formation. The taxon has been considered a synonym of co-existing Amblotherium pusillum, but can be distinguished by differences in the dental anatomy and an overall smaller size. Achyrodon was closely related to co-existing genus Phascolestes and the slightly younger European form Crusafontia, and together they make up the subfamily Kurtodontinae within Dryolestidae, a family of early mammals between modern monotremes and therians with no living descendants.
Spalacotherium is a genus of extinct mammal from the Early Cretaceous of Europe. The type species Spalacotherium tricuspidens was originally named by Richard Owen in 1854, and its material includes maxillary and dentary fragments and many teeth from the Berriasian Lulworth Formation of southern England. Referred species include S. taylori, S. evansae and S. hookeri also from the Lulworth deposits, and S. henkeli from Barremian deposits of Galve, Spain. The Lulworth taxon Peralestes longirostris, named by Owen in 1871, is a junior synonym of the type species S. tricuspidens. Spalacotherium is the namesake taxon of the family Spalacotheriidae, which is an extinct clade within Trechnotheria that may be closely related to the Gondwanan clade Meridiolestida, or united with the family Zhangheotheriidae to form Symmetrodonta.S. evansae is also from the Berriasian aged Angeac-Charente bonebed in western France.
Kouriogenys is a genus of extinct mammal from the Early Cretaceous of southern England. The type and only species was originally described as Spalacotherium minus by Richard Owen in 1871 for a dentary with teeth from the Berriasian Lulworth Formation, although it was given its own genus in 2012 by Brian Davis. The genus name is taken from the Ancient Greek "youthful" and "jaw" in reference to the replacement method of the premolars. Kouriogenys is closely related to coexisting genera Peramus and Peramuroides, and along with other genera these make up the family Peramuridae, a group of extinct zatherians.
Aerodraco is a genus of anhanguerid pterosaur from the Albian–Cenomanian-age Cambridge Greensand of England. It contains only one species, Aerodraco sedgwickii. It was originally assigned to the genus Pterodactylus.
