Gondwanatheria is an extinct group of mammaliaforms that lived in parts of Gondwana, including Madagascar, India, South America, Africa and Antarctica during the Upper Cretaceous through the Paleogene. Until recently, they were known only from fragmentary remains. They are generally considered to be closely related to the multituberculates and likely the euharamiyidians, well known from the Northern Hemisphere, with which they form the clade Allotheria.
Eutheria, also called Pan-Placentalia, is the clade consisting of placental mammals and all therian mammals that are more closely related to placentals than to marsupials.
Marsupial moles, the Notoryctidae family, are two species of highly specialized marsupial mammals that are found in the Australian interior. They are small fossorial marsupials that anatomically converge on fossorial placental mammals, such as extant golden moles (Chrysochloridae) and extinct epoicotheres (Pholidota). The species are:
The Australosphenida are a clade of mammals, containing mammals with tribosphenic molars, known from the Jurassic to Mid-Cretaceous of Gondwana. Although they have often been suggested to have acquired tribosphenic molars independently from those of Tribosphenida, this has been disputed. Fossils of australosphenidans have been found from the Jurassic of Madagascar and Argentina, and Cretaceous of Australia and Argentina. Monotremes have also been considered a part of this group in many studies, but this is also disputed.
Patagornis is a genus of extinct flightless predatory birds of the family Phorusrhacidae. Known as "terror birds", these lived in what is now Argentina during the Early and Middle Miocene; the Santa Cruz Formation in Patagonia contains numerous specimens. Patagornis was an agile, medium sized Patagornithine and was likely a pursuit predator.
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.
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.
Dryolestidae is an extinct family of Mesozoic mammals, known from the Middle Jurassic to the Early Cretaceous of the North Hemisphere. The oldest known member, Anthracolestes, is known from the Middle Jurassic Itat Formation of Western Siberia, but most other representatives are known from the Late Jurassic of North America and the Late Jurassic and Early Cretaceous of Europe. Most members are only known from isolated teeth and jaw fragments. Like many other groups of early mammals, they are thought to have been insectivores. They are generally classified in Cladotheria, meaning that they are considered to be more closely related to marsupials and placentals than to monotremes. They are placed as part of the broader Dryolestida, which also includes the Paurodontidae, and also sometimes the South American-Antarctic Meridiolestida, which are often considered unrelated cladotherians. Dryolestidae taxon 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.
Pantotheria is an abandoned taxon of Mesozoic mammals. This group is now considered an informal "wastebasket" taxon and has been replaced by Dryolestida as well as other groups. It is sometimes treated as an infraclass and older books refer to it as being related to symmetrodonts. One classification makes it an infraclass with a single order, Eupantotheria.
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.
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.
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.
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.
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.
Groeberiidae is a family of strange non-placental mammals from the Eocene and Oligocene epochs of Patagonia, Argentina and Chile, South America. Originally classified as paucituberculate marsupials, they were suggested to be late representatives of the allothere clade Gondwanatheria. However, the relationship of the type genus, Groeberia, to Gondwanatheria has been firmly rejected by other scholars.
Patagonia is an extinct genus of non-placental mammal from the Miocene of Argentina. Traditionally considered a metatherian incertae sedis, one analysis suggested it to be a gondwanathere. However, this has been rejected by other authors.
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.
