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upper left: upper molar Notopolytheles joelis in occlusal view. lower left: plagiaulacoid tooth of Argentodites coloniensis. Notopolytheles joelis Gelfo, Goin & Vega, 2025 |
Abstract
We report a left upper first molar of a multituberculate mammal, from the Upper Cretaceous La Colonia Formation, Chubut Province, Argentina, which is here assigned to Notopolytheles joelis gen. et sp. nov. (Cimolodonta,?Neoplagiaulacidae). Multituberculates have been previously reported from Gondwanan land masses, but to date, only records from Australia, Madagascar, and India have been taxonomically undisputed. In South America, all previous assignments were debated or later referred to Gondwanatheria. These records include isolated molars attributed to Ferugliotheriidae and Argentodites coloniensis, only known from a plagiaulacoid premolar and originally assigned to the ?Cimolodonta. Since no molar with definitive multituberculate features could ever be found in the Upper Cretaceous of Patagonia, A. coloniensis was considered a junior synonym of the ferugliotheriid Ferugliotherium windhauseni. Notopolytheles joelis gen. et sp. nov. displays a typical multituberculate molar configuration of three rows of tetrahedral cups, with a cusp formula of 7B:8M:4L similar to Neoplagiaulacidae. The lower position of the buccal cusp row supported by a single large labial root suggest a high level of endemism. This finding provides strong and renewed support for the hypothesis that ferugliotheriids lack a plagiaulacoid p4 and that Argentodites coloniensis is indeed a multituberculate.
Keywords: South America, Patagonia, La Colonia Formation, Late Cretaceous, Multituberculata, Gondwanatheria
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| Left: upper molar of the new species Notopolytheles joelis in occlusal view. Right: plagiaulacoid tooth of Argentodites coloniensis. Scale bar = 1 mm. |
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| Reconstruction of the small multituberculate Notopolytheles joelis from the Late Cretaceous La Colonia Formation, Chubut Province, Argentina. (by Manuel Copello) |
Mammalia Linnaeus, 1758.
Multituberculata Cope, 1884.
Cimolodonta McKenna, 1975.
?Neoplagiaulacidae Ameghino, 1890.
Notopolytheles joelis gen. and sp. nov.
Etymology: The genus name refers to ‘southern multituberculate’ and derives from three Greek roots: noto- (south), poly- (many), and theles (protuberance), the last two in reference to the multiple cusps characteristic of multituberculate teeth. The specific epithet joelis is named after Joel Hernán Carino, who discovered the tooth.
Javier N. Gelfo, Francisco J. Goin and Nahuel A. Vega. 2025. First unambiguous evidence of Multituberculata from the Late Cretaceous of South America. Scientific Reports. 15, 41500. DOI: doi.org/10.1038/s41598-025-25255-2 [24 November 2025]
A TINY FOSSIL TOOTH REWRITES THE HISTORY OF SOUTHERN MAMMALS
https://go.nature.com/4rnCGwU
