The function of proteins depends crucially on conformational motions. The characteristic times of these motions extend from sub-picosecond to seconds. No single experimental tool can cover the entire time range and provide all necessary parameters for a complete understanding. Moreover, without a solid understanding of the data evaluation it is easy to misinterpret the complex phenomena. Because protein motions are truly complex, the evaluation of the data even from such well-known techniques as neutron scattering (Magazu and Migliardo, 2011 [1]) and the Mossbauer effect (Chen and Yang, 2007 [2]) can lead to erroneous concepts and conclusions. We believe that notions such as the Lamb-Mossbauer relation, the protein dynamic transition, the protein glass transition, and the dynamic crossover are misleading or misapplied. To justify this statement we first briefly describe our view of dynamic proteins and then explain why we believe that these notions should be revised or abandoned. (C) 2013 Elsevier B.V. All rights reserved. (Less)