Energy flow in ecosystems

In the pre-1850 grasslands of North America there were hundreds of millions of grazing animals such as buffalo, antelope and deer. At the same time there were many fewer meat eaters, such as wolves. Explain in terms of energy flow in ecosystems and the Second law of Thermodynamics why there were so many grazers and so relatively few meat eaters. Would you expect more plants (such as grasses) tahn grazes, or fewer in the pre-1850 grasslands? Justify your response, be specific and complete.