Dinosaurs probably contributed minimally to this , stromberg says : they mainly had the wrong kind of teeth for ripping up grass , and the titanosaur coprolites indicate that grass was only a small part of their diet .

恐龙对此的贡献可能微乎其微，斯翠姆伯格说：主要是它们长错了牙齿，很难咬断青草，雷龙粪化石就表明青草只是它们饮食的一小部分。