"the vegetarian animals would have eaten the vegetable contents from the stomachs of the many drowned animals as animals still do to this day."
Name one herbivore that eats the vegetable matter from carcasses. Just one will do. BTW, animals are not "vegetarians." They are herbivores. Vegetarianism is an abberant behavior only among human beings. All other omnivores eat both meat and plant foods.
A very hungry one. Of course, vegetable matter and seeds were plentiful and didn't wash off the earth altogether. Oh, and I do like to name animals, so I would call him "Herb".