  Protein dynamics form a critical bridge between protein structure and
function, yet the impact of evolution on ultrafast processes inside proteins
remains enigmatic. This study delves deep into nanosecond-scale protein
dynamics of a structurally and functionally conserved protein across species
separated by almost a billion years, investigating ten homologs in complex with
their ligand. By inducing a photo-triggered destabilization of the ligand
inside the binding pocket, we resolved distinct kinetic footprints for each
homolog via transient infrared spectroscopy . Strikingly, we found a cascade of
rearrangements within the protein complex which manifest in three discrete time
points of dynamic activity, conserved over hundreds of millions of years within
a narrow window. Among these processes, one displays a subtle temporal shift
correlating with evolutionary divergence, suggesting reduced selective pressure
in the past. Our study not only uncovers the impact of evolution on molecular
processes in a specific case, but has also the potential to initiate a novel
field of scientific inquiry within molecular paleontology, where species are
compared and classified based on the rapid pace of protein dynamic processes; a
field which connects the shortest conceivable time scale in living matter
(10^-9 s) with the largest ones (10^16 s).
