Neoplagiaulacid multituberculates are among the most numerous and best represented members of early Cenozoic North American mammal faunas, achieving their greatest diversity during the Paleocene. Despite their relatively dense record in the Torrejonian (middle Paleocene) and Tiffanian (late Paleocene), the study of early Cenozoic neoplagiaulacids has been limited more often than not to isolated teeth or, more rarely, incomplete skull, gnathic, or postcranial remains. The current study reports on new neoplagiaulacid multituberculates from the Paleocene Paskapoo Formation of central Alberta, Canada, at localities along the Blindman River near the City of Red Deer. The exceptionally well-preserved specimens consist of incomplete articulated and associated skull and gnathic remains, and collectively document four new species: Ectypodus elaphus, Neoplagiaulax serrator, Neoplagiaulax paskapooensis, and Neoplagiaulax cimolodontoides. Neoplagiaulax paskapooensis is the most dentally complete neoplagiaulacid so far discovered, with a single specimen documenting for the first time left and right I2 and I3 in situ with the cheek teeth, along with the associated lower dentition. Specimens of Neoplagiaulax cimolodontoides record important details of the rostrum and palate, and provide the first direct evidence of incisor replacement in Neoplagiaulax. The new neoplagiaulacids, together with other multituberculates from the Blindman River localities, document unusually high multituberculate diversity in the latter half of the Tiffanian in western Canada. Despite superficial similarity to some European species of Neoplagiaulax, the new taxa from the Paskapoo Formation apparently show no closer relationship to these than do other North American congeners, suggesting parallel evolution in endemic North America and western European clades.

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