 Carpenter also noted that the occasional presence of large petrified logs indicate the presence of tall trees, which would seem to conflict with the savanna comparison.However, the trees are rare, and since tall trees require more water than the savanna environment could generally provide, they probably existed in narrow tracts or "gallery forests" along rivers and gulleys where water could accumulate.Carpenter speculated that giant herbivores like "Amphicoelias" may have used the shade of the gallery forests to stay cool during the day, and done most of their feeding on the open savanna at night.