Many of the other fossils we have discovered in Chile come from a variety of localities in the central part of the country. All of these sites apparently sample the Abanico Formation, a group of rocks that was deposited mainly between about 40 million and 15 million years ago. This particular formation tends to preserve specimens in great detail, but the matrix (the rock surrounding the specimen) is typically very hard. This means it usually takes weeks to prepare (i.e., clean) a single specimen. This obviously slows down our research quite a bit, since the fossils must be prepared before they can be described. We have published papers on particular specimens from some of these other faunas, but most are awaiting preparation and/or further study. A current focus of our group is compiling provisional species lists for these faunas in order to make preliminary age and biostratigraphic interpretations. This is particularly important for this area, since different parts of the Abanico Formation were deposited at different times. We plan to supplement these fossil-based age estimates with radiometric dates wherever layers suitable for dating are present. Together, these faunas and their associated dates will be very useful for: (1) better understanding the tectonic and uplift histories of the Central Andes; (2) increasing the number of time slices represented by fossil mammals in Chile; and (3) expanding the geographic sampling of fossil mammal localities in South America.