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Ferugliotheriidae is one of two 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 (molar-like tooth), from a different Late Cretaceous Argentinean locality. Another genus known from a single tooth (in this case, a fourth lower premolar), ''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, may represent a related animal. Ferugliotheriids are known from isolated, low-crowned (brachydont) teeth and possibly a fragment of a lower jaw. ''Ferugliotherium'' is estimated to have weighed 70 g (2.5 oz). The incisors are long and procumbent and contain a band of enamel on only part of the tooth. The jaw fragment contains a long tooth socket for the incisor and bears a bladelike fourth lower premolar, resembling those of multituberculates. The premolar of ''Argentodites'' is similar. Two upper premolars also resemble multituberculate teeth, but whether these premolars are referable to Ferugliotheriidae is controversial. Molariforms are rectangular and brachydont and consist of longitudinal rows of cusps, connected by transverse crests and separated by transverse furrows. Lower molariforms have two cusp rows, and the single known putative upper molariform has three. Low-crowned and bladelike teeth as seen in ferugliotheriids may have been evolutionary precursors of the high-crowned (hypsodont) teeth of the other gondwanathere family, Sudamericidae. Most ferugliotheriids come from the Late Cretaceous epoch (Campanian–Maastrichtian ages, 84–66 million years ago, or mya) of Argentina, where they may have lived in a marshy or seashore environment. They coexisted with mammals such as dryolestoids and a variety of other animals, including dinosaurs. Ferugliotheriids may have been herbivores or omnivores. ==Taxonomy== The first member of the family Ferugliotheriidae to be discovered, ''Ferugliotherium windhauseni'', was named in 1986 by Argentinean paleontologist José F. Bonaparte on the basis of a tooth from the Late Cretaceous Los Alamitos Formation of Argentina. Bonaparte placed ''Ferugliotherium'' as the only member of the new family Ferugliotheriidae, which he tentatively assigned to the order Multituberculata, a large group of extinct mammals (distinct from both monotremes and therians, the two major groups of living mammals) that was particularly widespread in the northern continents (Laurasia), but had never previously been found in the south (Gondwana). In 1990, Bonaparte named another species, ''Vucetichia gracilis'', from Los Alamitos. He placed it in the family Gondwanatheriidae, together with ''Gondwanatherium'', another Los Alamitos mammal, within the order Gondwanatheria, which also contained the family Sudamericidae, then with the single genus ''Sudamerica''. Bonaparte considered the gondwanatheres to be probably most closely related to the xenarthrans (sloths, armadillos, and anteaters) within a group called Paratheria. Also in 1990, Bonaparte merged the family Gondwanatheriidae into Sudamericidae and, together with David Krause, redefined Gondwanatheria as a multituberculate suborder that included both Ferugliotheriidae and Sudamericidae, thus rejecting a relationship between gondwanatheres and xenarthrans. Krause, Bonaparte, and Zofia Kielan-Jaworowska redescribed ''Ferugliotherium'' in 1992 and suggested that the teeth that ''Vucetichia'' was based on may have been worn specimens of ''Ferugliotherium''. They placed ''Ferugliotherium'' among multituberculates and suggested that it may be part of the suborder Plagiaulacoidea. The following year, Krause confirmed that ''Vucetichia gracilis'' is a synonym of ''Ferugliotherium windhauseni''. Together with Bonaparte, he also proposed to classify gondwanatheres as a superfamily (Gondwanatherioidea) within Plagiaulacoidea, including the families Ferugliotheriidae and Sudamericidae. In 1996, Kielan-Jaworowska and Bonaparte tentatively identified a lower jaw fragment with a multituberculate-like fourth lower premolar (p4) from Los Alamitos as ''Ferugliotherium''. On the basis of the morphological features of the jaw fragment, they argued that gondwanatheres are not closely related to any other multituberculate group, and consequently placed them in a suborder of their own, Gondwanatheria. In 1999, Rosendo Pascual and colleagues described a lower jaw of ''Sudamerica'', which had previously only been known from isolated teeth. This jaw fragment showed that ''Sudamerica'' had four molariform (molar-like teeth) on each side of the lower jaws, more than any multituberculate, and consequently they removed gondwanatheres from Multituberculata and regarded their affinities as uncertain. As a consequence, Kielan-Jaworowska and colleagues excluded Gondwanatheria from multituberculates, but identified the jaw fragment and a few upper premolars of ''Ferugliotherium'' as indeterminate multituberculates in a 2001 paper and a 2004 book. However, in 2009 Yamila Gurovich and Robin Beck identified these fossils as ''Ferugliotherium'' and argued in favor of a close relationship between gondwanatheres (including Ferugliotheriidae) and multituberculates. In the 2000s, additional members of Ferugliotheriidae were described. In 2004, Francisco Goin and colleagues described a single enigmatic tooth from the Paleogene of Peru, LACM 149371; their best estimate was that it represented a member of Ferugliotheriidae. On the basis of a single p4, Kielan-Jaworowska and colleagues named ''Argentodites coloniensis'', from the Late Cretaceous La Colonia Formation of Argentina, in 2007 as a multituberculate, possibly referable to the suborder Cimolodonta. However, Gurovich and Beck argued that the p4 of ''Argentodites'' did not differ materially from that in the jaw they allocated to ''Ferugliotherium'', and that ''Argentodites'' was based on a specimen of either ''Ferugliotherium'' or a closely related animal. Guillermo Rougier and colleagues described mammals from the Allen Formation, a third Argentinean formation of similar age, in 2009, including a new ferugliotheriid, ''Trapalcotherium matuastensis''. They also regarded ''Argentodites'' as a likely relative of ''Ferugliotherium'' and suggested that Ferugliotheriidae are either multituberculates or closely related to them. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ferugliotheriidae」の詳細全文を読む スポンサード リンク
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