It is easy to find numerous fossil elements of Mosasaurs in the Maastrichtian sedimentary levels of In Daman, Niger. Unfortunately, this material is almost always very fragmentary : it consists essentially in isolated teeth, vertebrae or mandibles. We use metric methods in order to clearly identify 6 different species and compare them to previously described species from Niger or Nigeria. We found two species already known : Igdamanosaurus aegyptiacus and Goronyosaurus nigeriensis. A third species, a Plioplatecarpinae, is sufficiently well documented in order to create a new name : Platecarpus indamanensis nov. sp. The three remaining species are poorly defined. Nevertheless, two of them can be related to the genus Halisaurus. But it is not necessary at this stage to create new species. The last species possesses strong crushing teeth and can perharps be related to Globidentinae.