Microcosmodontidae is a poorly preserved family of fossil

Fossil

Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

 mammals within the extinct order Multituberculata

Multituberculata

The Multituberculata were a group of rodent-like mammals that existed for approximately one hundred and twenty million years—the longest fossil history of any mammal lineage—but were eventually outcompeted by rodents, becoming extinct during the early Oligocene. At least 200 species are...

. Representatives are known from the Upper Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 though the Lower Paleocene

Paleocene

The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...

 of North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. The family is part of the suborder Cimolodonta

Cimolodonta

The Cimolodonta are a taxon of extinct mammals that lived from the Cretaceous to the Eocene. They were some of the more derived members of the extinct order Multituberculata. They probably lived something of a rodent-like existence until their ecological niche was assumed by true rodents...

. Other than that, their systematic relationships are hard to define.

These microcosmodontids were rather small and had a "large lower incisor with a restricted enamel band, (Kielan-Jaworowska & Hurum 2001, p.417). This grouping has also be seen as Microcosmodontinae Holtzman & Wolberg, 1977, within Eucosmodontidae

Eucosmodontidae

Eucosmodontidae is a poorly preserved family of fossil mammals within the extinct order Multituberculata. Representatives are known from strata dating from the Upper Cretaceous through the Lower Eocene of North America, as well as the Paleocene to Eocene of Europe. The family is part of the...

. However, "Microcosmodontidae (new rank assigned by Fox to the subfamily Microcosmodontinae)," (Kielan-Jaworowska & Hurum, 2001).