Ferugliotherium windhauseni

Ferugliotherium is a genus of fossil mammals in the family Ferugliotheriidae from the Campanian and/or Maastrichtian period (Late Cretaceous; around 70 million years ago) 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 (collectively known as Gondwanatheria) 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. About twenty teeth and a jaw fragment have been referred to Ferugliotherium, but the assignment of many of these is controversial or has been superseded. The upper and lower incisors are long and rodent-like and have enamel on only one side of the crown. A fragment of the lower jaw shows that the tooth socket of the lower incisor was very long, extending below the fourth premolar (p4). The p4 is preserved in this fragment. It is blade-shaped and resembles multituberculate p4s. However, the determination of this fossil as Ferugliotherium is in question. The identity of a few additional isolated premolars assigned to Ferugliotherium, some resembling multituberculates, is also uncertain. The first lower molariform (molar-like tooth; mf1) is known from four examples, of which two were originally identified as upper molars of a different species (Vucetichia gracilis), which is now considered a synonym of Ferugliotherium. They bear two longitudinal rows of three or four cusps and transverse crests and furrows.