In vertebrate paleontology, it is imperative to directly examine fossils when conducting research. If a museum is too far away and too expensive to visit, then a good cast makes for an excellent alternative. Sometimes we will get the chance to examine important specimens in person - but if they are particularly important, for example - closely related to a fossil under study - then possessing a cast for comparison and longish term study is just as useful. For example, I've never had the opportunity to visit France or South Africa, but at the Smithsonian I was able to examine and photograph casts of the true seals Piscophoca and Homiphoca (in collections of said countries); similarly, I have not made plans (and will not have the budget) to visit collections in Japan, and in our department we have a cast of the Oligocene Japanese mysticete Aetiocetus polydentatus.
Recently, Yoshi has been making numerous casts of the Oligocene dolphin Waipatia maerewhenua, one of the most completely known Oligocene cetaceans - for trading with other institutions. So far, casts of Waipatia have gotten us casts of Piscobalaena from the MNHN, Aetiocetus polydentatus from the Ashoro Museum of Paleontology, and most recently - the early Miocene longirostrine odontocete Squalodelphis fabianii from Italy.
We also received a fresh copy of Giorgio Pilleri's enormous (if ponderous) and beautifully illustrated monograph on the Odontoceti of the early Miocene Belluno Sandstone of Italy.
Labmate Yoshi Tanaka pulls out a bubble wrapped skull.
Gorgeous! Yoshi and I ogling the the freshly unwrapped cast of the holotype of Squalodelphis fabianii.
It's like Christmas morning for a paleocetologist!