What does that mean to you? Did some herbivores become carnivores when Adam sinned? Did plant eating snakes, of which so far as I know do not even exist, suddenly, the moment Adam disobeyed, develop venom and fangs or become constrictors? Did lions, tigers, dogs, cats, suddenly lose the digestive process for plant food and develop the digestive processes, and other functions as carnivorous animals?
Or was it just that there were no carnivores in the Garden?
Or could it be that all that is meant there is that all animal life, whether carnivore or herbivore begins with plant food. That is, the carnivore depends on the herbivore which depends on plant food. Without plant food all animal life ceases to exist.
Also does it mean that some plants initially given for food suddenly become poisonous when Adam sinned?