Phylogenic Tree of Cyanobacteria (Fig.2) (image) Toyohashi University of Technology Caption Phylogenic tree of cyanobacteria. Ancestral cyanobacteria acquired PEC and the photosensor, each only once, about 2.1 billion years ago or more. Credit COPYRIGHT (C) TOYOHASHI UNIVERSITY OF TECHNOLOGY. ALL RIGHTS RESERVED. Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.