* Anteaters: These are found primarily in tropical forests of Central and South America.
* Pangolins: These mammals are found in tropical forests, grasslands, and savannas of Africa and Asia.
* Sloths: These are found in tropical rainforests of Central and South America.
* Aardvarks: These are found in savannas and grasslands of sub-Saharan Africa.
Therefore, tropical forests and grasslands/savannas seem to be the most common habitats for toothless mammals.
However, it's important to remember that the distribution of these animals varies depending on the species. Some species, like the pangolin, are found in a wider range of habitats than others.