Ferugliotherium - Taxonomy

Taxonomy

Ferugliotherium windhauseni was named in 1986 by Argentinean paleontologist José Bonaparte on the basis of a single second lower molar (m2) from the Late Cretaceous Los Alamitos Formation of Argentina. Both the generic name, Ferugliotherium, and the specific name, windhauseni, honor geologists who studied the geology of Patagonia: Egidio Feruglio and Anselmo Windhausen, respectively. Bonaparte created a new family, Ferugliotheriidae, for the new species and tentatively assigned it to Multituberculata, an extinct group of mammals that was diverse during the late Cretaceous, mostly in the northern continents (Laurasia). In subsequent years, other finds permitted a more confident assignment to Multituberculata. In 1990, Bonaparte described Vucetichia gracilis on the basis of what he interpreted as two upper molars of a relative of Gondwanatherium within the order Gondwanatheria, a small mammalian group that was at the time known only from Argentinean fossils and thought to be related to xenarthrans as part of a group called Paratheria. The generic name, Vucetichia, commemorates Argentinean paleontologist Guiomar Vucetich, and the specific name, gracilis (Latin for "slender"), refers to the animal's small size.

However, in 1990 David Krause and Bonaparte argued that Gondwanatheria, including Ferugliotherium (family Ferugliotheriidae), Gondwanatherium, and Sudamerica (family Sudamericidae), should be placed within Multituberculata. Two years later, Krause, Bonaparte, and Zofia Kielan-Jaworowska described additional material of Ferugliotherium (which they tentatively placed in the multituberculate suborder Plagiaulacoidea) and suggested that the supposed upper molars of Vucetichia were in fact heavily worn first lower molariforms (mf1) of Ferugliotherium. In 1993, Krause described an unworn mf1 of Ferugliotherium and confirmed that Vucetichia was based on worn specimens of Ferugliotherium and therefore a synonym of the latter. In the same year, he and Bonaparte argued once again that Ferugliotherium, Gondwanatherium, and Sudamerica formed a closely related group of mulituberculates, which they called the superfamily Gondwanatherioidea. Kielan-Jaworowska and Bonaparte described a lower jaw fragment with a multituberculate-like lower fourth premolar (p4) from Los Alamitos in 1996 and tentatively identified it as Ferugliotherium. On the basis of the morphological features of the jaw fragment, they argued that gondwanatherians were 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 jaw of Sudamerica. Because some of this jaw's features were thought to be incompatible with a multituberculate identity, they regarded gondwanatheres (including Ferugliotherium) as Mammalia incertae sedis. However, in 2009 Yamila Gurovich and Robin Beck argued in favor of a close relationship between gondwanatheres (including Ferugliotherium) and multituberculates. The controversy is partially due to disagreement over the assignment of two upper premolars and the jaw fragment described by Kielan-Jaworowska and Bonaparte in 1996; Gurovich and Beck identify these as Ferugliotherium, while Kielan-Jaworowska and others regard them as indeterminate multituberculates.

In the 2000s, some possible close relatives of Ferugliotherium were discovered. An enigmatic tooth from the Paleogene of Peru, LACM 149371, was described in 2004 as possibly related to the family Ferugliotheriidae. Kielan-Jaworowska and colleagues described a p4 from the La Colonia Formation (Late Cretaceous of Argentina) as a new multituberculate genus, Argentodites, in 2007, but Gurovich and Beck noted close similarities between this p4 and the p4 in the possible jaw fragment of Ferugliotherium and suggested that it represented Ferugliotherium or a closely related species. A single mf1 from the Allen Formation (Late Cretaceous of Argentina) was described as another ferugliotheriid genus, Trapalcotherium, in 2009.