Ferugliotherium is a genus of fossil mammals in the family Ferugliotheriidae from the Campanian and/or Maastrichtian period of Argentina. It contains a single species, Ferugliotherium windhauseni, which was first described in 1986. Although originally interpreted on the basis of a single brachydont (low-crowned) molar as a member of Multituberculata, an extinct group of small, rodent-like mammals, it was recognized as related to the hypsodont (high-crowned) Sudamericidae following the discovery of additional material in the early 1990s. After a jaw of the sudamericid Sudamerica was described in 1999, these animals were no longer considered to be multituberculates and a few fossils that were previously considered to be Ferugliotherium were assigned to unspecified multituberculates instead. Since 2005, a relationship between gondwanatheres and multituberculates has again received support. A closely related animal, Trapalcotherium, was described in 2009 on the basis of a single tooth.
Ferugliotheriidae is one of three known families in the order Gondwanatheria, an enigmatic group of extinct mammals. Gondwanatheres have been classified as a group of uncertain affinities or as members of Multituberculata, a major extinct mammalian order. The best-known representative of Ferugliotheriidae is the genus Ferugliotherium from the Late Cretaceous epoch in Argentina. A second genus, Trapalcotherium, is known from a single tooth, a first lower molariform, from a different Late Cretaceous Argentinean locality. Another genus known from a single tooth, Argentodites, was first described as an unrelated multituberculate, but later identified as possibly related to Ferugliotherium. Finally, a single tooth from the Paleogene of Peru, LACM 149371, perhaps a last upper molariform, and a recent specimen from Mexico, may represent related animals.
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.
Vincelestes is an extinct genus of mammal that lived in what is now South America during the Early Cretaceous. It is closely related to modern therian mammals as part of Cladotheria.
Deltatheroida is an extinct group of basal metatherians that were distantly related to modern marsupials. The majority of known members of the group lived in the Cretaceous; one species, Gurbanodelta kara, is known from the late Paleocene (Gashatan) of China. Their fossils are restricted to Central Asia and North America. This order can be defined as all metatherians closer to Deltatheridium than to Marsupialia.
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.
Peligrotherium is an extinct meridiolestidan mammal from the Paleocene of Patagonia, originally interpreted as a stem-ungulate. Its remains have been found in the Salamanca Formation. It was a dog-sized mammal, among the largest of all non-therian mammals. It is a member of Mesungulatoidea, a clade of herbivorous meridiolestidans with molars that had rounded (bunodont) cusps.
Shuotherium is a fossil mammaliaform known from Middle-Late Jurassic of the Forest Marble Formation of England, and the Shaximiao Formation of Sichuan, China.
Cladotheria is a clade of mammals. It contains modern therian mammals and several extinct groups, such as the "dryolestoids", amphitheriids and peramurids. The clade was named in 1975 by Malcolm McKenna. In 2002, it was defined as a node-based taxon containing "the common ancestor of dryolestids and living therians, plus all its descendants". A different, stem-based definition was given in 2013, in which Cladotheria contains all taxa that are closer to Mus musculus than to the "symmetrodont" Spalacotherium tricuspidens.
Ambondro mahabo is a mammal from the Middle Jurassic (Bathonian) Isalo III Formation of Madagascar. The only described species of the genus Ambondro, it is known from a fragmentary lower jaw with three teeth, interpreted as the last premolar and the first two molars. The premolar consists of a central cusp with one or two smaller cusps and a cingulum (shelf) on the inner, or lingual, side of the tooth. The molars also have such a lingual cingulum. They consist of two groups of cusps: a trigonid of three cusps at the front and a talonid with a main cusp, a smaller cusp, and a crest at the back. Features of the talonid suggest that Ambondro had tribosphenic molars, the basic arrangement of molar features also present in marsupial and placental mammals. It is the oldest known mammal with putatively tribosphenic teeth; at the time of its discovery it antedated the second oldest example by about 25 million years.
Several mammals are known from the Mesozoic of Madagascar. The Bathonian Ambondro, known from a piece of jaw with three teeth, is the earliest known mammal with molars showing the modern, tribosphenic pattern that is characteristic of marsupial and placental mammals. Interpretations of its affinities have differed; one proposal places it in a group known as Australosphenida with other Mesozoic tribosphenic mammals from the southern continents (Gondwana) as well as the monotremes, while others favor closer affinities with northern (Laurasian) tribosphenic mammals or specifically with placentals. At least five species are known from the Maastrichtian, including a yet undescribed species known from a nearly complete skeleton that may represent a completely new group of mammals. The gondwanathere Lavanify, known from two teeth, is most closely related to other gondwanatheres found in India and Argentina. Two other teeth may represent another gondwanathere or a different kind of mammal. One molar fragment is one of the few known remains of a multituberculate mammal from Gondwana and another has been interpreted as either a marsupial or a placental.
Argentodites is a possible multituberculate mammal from the Cretaceous of Argentina. The single species, Argentodites coloniensis, is known from a single blade-like fourth lower premolar (p4) from the La Colonia Formation, which is mostly or entirely Maastrichtian in age. The p4 is 4.15 mm long and bears eight cusps on its upper margin and long associated ridges on both sides. The enamel consists of prisms that are completely or partly surrounded by a sheath and that are on average 6.57 μm apart. Zofia Kielan-Jaworowska, who described and named the fossil in 2007, regarded it as a multituberculate, perhaps a cimolodontan—and thus, a member of a mostly Laurasian (northern) group and an immigrant to Argentina from North America—on the basis of the shape of the tooth and features of its enamel. In 2009, however, two teams argued that Argentodites may in fact be close to or identical with Ferugliotherium, a member of the small Gondwanan (southern) group Gondwanatheria; although their relationships are disputed, gondwanatheres may themselves be multituberculates.
Trapalcotherium is a fossil mammal from the Cretaceous of Argentina in the family Ferugliotheriidae. The single species, T. matuastensis, is known from one tooth, a first lower molar. It is from the Allen Formation, which is probably Maastrichtian in age, and was first described in 2009. The tooth bears two rows of cusps, one at the inner (lingual) side and the other at the outer (labial) side, which are connected by transverse ridges separated by deep valleys. This pattern is reminiscent of Ferugliotherium, a gondwanathere mammal from similarly aged deposits in Argentina, and Trapalcotherium is therefore recognized as a member of the same family Ferugliotheriidae. Ferugliotheriidae is one of two families of gondwanatheres, an enigmatic group without close relationships to any living mammals.
Reigitherium was a mammal that lived during the Late Cretaceous, in the. Its fossils have been found in the Los Alamitos and the La Colonia Formations of Argentina.
Donodon is an extinct genus of mammal from the Ksar Metlili Formation of Talssint, Morocco, which has been dated to the Late Jurassic to Early Cretaceous epochs. The type species D. perscriptoris was described in 1991 by the palaeontologist Denise Sigogneau-Russell. A second species, D. minor, was named in 2022. Donodon was a member of Cladotheria, a group that includes therian mammals and some of their closest relatives. It differed from dryolestids in having upper molars that were not compressed mesiodistally. Some studies have suggested that it was closely related to various South American cladotherians in the clade Meridiolestida, with specific similarities to Mesungulatum, a herbivorous mesungulatid, being noted. On the other hand, a 2022 phylogenetic analysis found it to be only distantly related to meridiolestidans, and instead closer to crown group therians.
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.
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.
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.
Groebertherium is a genus of dryolestoid mammal from the Late Cretaceous Los Alamitos and Allen Formations of Argentina. It is not closely related to other contemporary dryolestoids, all of which are part of the clade Meridiolestida.
