A new earliest Paleocene (Puercan) fauna from the Denver Formation in Colorado's Denver Basin.

摘要

Renewed collecting from an earliest Paleocene (Puercan) locality on the eastern side of the Denver Basin has produced a diverse assemblage of Puercan vertebrates. Based on its faunal composition, low observed diversity, absence of larger, more derived middle/late Puercan taxa, and close stratigraphic proximity to the well-defined Cretaceous-Paleogene (K-Pg) boundary, the assemblage likely represents a fauna older than the Littleton Fauna and is temporally correlative to Pu1 faunas in NE Montana and Wyoming. I report the occurrence of at least three species of multituberculates including two species of Mesodma, the marsupial Thylacodon sp., and several 'condylarth' species, including Protungulatum donnae, Oxyprimus galadrielae, and index taxa Baioconodon nordicum. The presence of Mesodma, O. galadrielae, and P. donnae is consistent with a Pu1 age. This study documents the southernmost early Pu1 fauna yet known, suggesting early Puercan mammalian diversity in the Denver Basin may be greater than previously thought.