  Bifurcations in a system of coupled maps are investigated. Using symbolic
dynamics it is proven that for coupled shift maps the well known
space--time--mixing attractor becomes unstable at a critical coupling strength
in favour of a synchronized state. For coupled non--hyperbolic maps analytical
and numerical evidence is given that arbitrary small coupling changes the
dynamical behaviour. The anomalous dependence of fluctuations on the system
size is attributed to these bifurcations.
