Kimbetopsalis simmonsae was an ancient mammal (a multituberculate) which was first discovered in 2015.[2][3]
It lived about 65.5 million years ago, at least a million years after the non-avian dinosaurs went extinct.[4]
References
^Willamson, T.E.; Brusatte, S.L.; Secord, R.; Shelley, S (2016), "A new taeniolabidoid multituberculate (Mammalia) from the middle Puercan of the Nacimiento Formation, New Mexico, and a revision of taeniolabidoid systematics and phylogeny", Zoological Journal of the Linnean Society, 177: 183–208, doi:10.1111/zoj.12336