Sentence:  Wavy lines , feather like patterns , rosettes of indefinitely floral nature , birds either singly or in stylized rows , animals in solemn frieze bands ( see Plates 11 - 12 ) - all these turned up in the more developed fabrics as preliminary <WSD>signs</WSD> that the potters were broadening their gaze . 
Meaning of the word marked with <WSD> tags:  a perceptible indication of something not immediately apparent (as a visible clue that something has happened)