  Specific heat measurements and theoretical calculations reveal an intimate
analogy between EuTiO3 and SrTiO3. For EuTiO3 a hitherto unknown specific heat
anomaly is discovered at TA=282(1)K which is analogous to the well known
specific heat anomaly of SrTiO3 at TA=105K caused by an antiferrodistortive
transition. Since the zone center soft phonon mode observed in both systems can
be modeled with the same parameters we ascribe the new 282(1)K instability of
EuTiO3 to an antiferrodistortive phase transition. The higher transition
temperature of EuTiO3 as compared to SrTiO3 results from spin phonon coupling.
