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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.
Neoplagiaulacidae is a family of mammal within the extinct order Multituberculata. Fossil remains are known from the Upper Cretaceous through to the latest Eocene/early Oligocene. Representatives have been found in North America, Europe and Asia. They are the last multituberculates known.
Mesodma is an extinct genus of mammal, a member of the extinct order Multituberculata within the suborder Cimolodonta, family Neoplagiaulacidae. It lived during the upper Cretaceous and Paleocene Periods of what is now North America. The earliest definitive record is from the late Santonian stage strata of the Straight Cliffs Formation. A single premolar tooth from the lower Cenomanian stage strata of the Cedar Mountain Formation has been tentatively assigned to this genus based on its similarity, but its describers noted that it is unlikely that Mesodma lived during that time.
Parectypodus is an extinct genus of mammals that lived from Late Cretaceous (Maastrichtian) to Eocene time in North America. It is a member of the extinct order of Multituberculata, suborder Cimolodonta, family Neoplagiaulacidae. It was named by G.L. Jepsen in 1930.
Cimolodon is a genus of the extinct mammal order of Multituberculata within the suborder Cimolodonta and the family Cimolodontidae. Specimens are known from the Late Cretaceous of North America.
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 isolated teeth, a few lower jaws, two partial skulls and one complete cranium. 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.
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.
Repenomamus is a genus of opossum- to badger-sized gobiconodontid mammal containing two species, Repenomamus robustus and Repenomamus giganticus. Both species are known from fossils found in China that date to the early Cretaceous period, about 125-123.2 million years ago. R. robustus is one of several Mesozoic mammals for which there is good evidence that it fed on vertebrates, including dinosaurs, though it is not possible to determine if it actively hunted live dinosaurs or scavenged dead ones. R. giganticus is among the largest mammals known from the Mesozoic era.
Alamosaurus is a genus of opisthocoelicaudiine titanosaurian sauropod dinosaurs, containing a single known species, Alamosaurus sanjuanensis, from the late Cretaceous Period of what is now southern North America. Isolated vertebrae and limb bones indicate that it reached sizes comparable to Argentinosaurus and Puertasaurus, which would make it the largest dinosaur known from North America. Its fossils have been recovered from a variety of rock formations spanning the Maastrichtian age of the late Cretaceous period. Specimens of a juvenile Alamosaurus sanjuanensis have been recovered from only a few meters below the Cretaceous-Paleogene boundary in Texas, making it among the last surviving non-avian dinosaur species.
Rugops is a monospecific genus of basal abelisaurid theropod dinosaur from Niger that lived during the Late Cretaceous period in what is now the Echkar Formation. The type and only species, Rugops primus, is known only from a partial skull. It was named and described in 2004 by Paul Sereno, Jeffery Wilson and Jack Conrad. Rugops has an estimated length of 4.4–5.3 metres and weight of 410 kilograms. The top of its skull bears several pits which correlates with overlaying scale and the front of the snout would have had an armour-like dermis.
The Lance (Creek) Formation is a division of Late Cretaceous rocks in the western United States. Named after Lance Creek, Wyoming, the microvertebrate fossils and dinosaurs represent important components of the latest Mesozoic vertebrate faunas. The Lance Formation is Late Maastrichtian in age, and shares much fauna with the Hell Creek Formation of Montana and North Dakota, the Frenchman Formation of southwest Saskatchewan, and the lower part of the Scollard Formation of Alberta.
Simosuchus is an extinct genus of notosuchian crocodylomorphs from the Late Cretaceous of Madagascar. It is named for its unusually short skull. Fully grown individuals were about 0.75 metres (2.5 ft) in length. The type species is Simosuchus clarki, found from the Maevarano Formation in Mahajanga Province, although some fossils have been found in India.
The Laramie Formation is a geologic formation of Late Cretaceous (Maastrichtian) age, named by Clarence King in 1876 for exposures in northeastern Colorado, in the United States. It was deposited on a coastal plain and in coastal swamps that flanked the Western Interior Seaway. It contains coal, clay and uranium deposits, as well as plant and animal fossils, including dinosaur remains.
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. 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. 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.
Paressonodon is an extinct genus of multituberculate which existed in Colorado during the late Cretaceous period. It contains the species Paressonodon nelsoni.
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.
The Willwood Formation is a sedimentary sequence deposited during the late Paleocene to early Eocene, or Clarkforkian, Wasatchian and Bridgerian in the NALMA classification.
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.
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.
References
- ↑ Gregory P. Wilson, Marieke Dechesne & Ingrid R. Anderson (2010). "New Late Cretaceous mammals from northeastern Colorado with biochronologic and biogeographic implications". Journal of Vertebrate Paleontology . 30 (2): 499–520. doi:10.1080/02724631003620955. S2CID 92991955.
- ↑ Wilson et al., 2010, op. cit.
- ↑ Donohue; et al. (2013). "Latest Cretaceous multituberculate of the Black Butte Station local fauna (Lance Formation, southwest Wyoming), with implications for compositional differences among mammalian local fauna of the Western interior". Journal of Vertebrate Paleontology . 33 (3): 677–695. doi:10.1080/02724634.2013.745416. S2CID 55614488.
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