The genus Hypnodontopsis is represented by three extant species, all with a very limited distribution. One was described as H. mexicana (Thér.) Robins., only known from single localities in Mexico and Uganda, another is H. apiculata Iwats. and Nog., only known from a small area in Japan, and the last is H. spathulata H. Akiyama and A. Tanaka, recently described from Burma. The genus was, however, present in the Eocene (ca 45–58 myr bp) with five species; one of which is identical to the extant H. mexicana and is the most common moss in Baltic amber. All fossil species are illustrated and described. They are distinguished by variation of character states such as apiculate, lingulate, and piliferous leaves. The fact that the genus consisted of five (known) species in Tertiary, some of them very common, but only three extant species, which are quite rare, shows a decline of species number and frequency.