sentences:  Tracheophytes also developed vascular tissue to aid in the movement of water within the organisms (see below), and moved away from a gametophyte dominated life cycle (see below).Vascular tissue ultimately also facilitated upright growth without the support of water and paved the way for the evolution of larger plants on land.A snowball earth, from around 850-630 mya, is believed to have been caused by early photosynthetic organisms, which reduced the concentration of carbon dioxide and increased the amount of oxygen in the atmosphere.