The Paracimexomys group is a loose grade of extinct mammals which are known from the Lower Cretaceous and possibly through to the Paleocene of North America.
They were members of an also extinct order called Multituberculata.
These were generally small, somewhat rodent-like creatures, some of whom shared the world with dinosaurs. As remains are rather sparse, it's not yet been possible to define this group with more certainty.
These mammals seem to represent animals that were anatomically somewhere between the more basal "Plagiaulacida" and the further derived members of Cimolodonta. The affinities of Cimexomys and Cedaromys are even less well established.
References
- Kielan-Jaworowska Z & Hurum JH (2001), "Phylogeny and Systematics of multituberculate mammals". Paleontology 44, p.389-429.
- Much of this information has been derived from [1] (http://home.arcor.de/ktdykes/cimolod.htm) MESOZOIC MAMMALS; "basal" Cimolodonta, Cimolomyidae, Boffidae and Kogaionidae, an Internet directory.