PPT Slide
- Plant eating arose many times in tetrapods.
- Plant feeding animals use two different strategies for dealing with this problem.
- Be small and picky - avoid cellulose-rich plant parts; only eat nutrient-rich plant parts (fruits & nuts). There is only enough high-nutrient food to support small animals with this strategy.
- Be big and indiscriminate - eat everything that you can. Pack your gut with microbes and let them ferment this low quality food. Eat the microbes and the waste products they exude. Must be large to fit the massive, fermenting-chamber gut.
- Herbivorous pelycosaurs took the big, indiscriminate route.Ý
- They were large, and probably evolved from large carnivorous ancestors.Ý
- They had small heads, so cellulose digestion must have come from microbes.Ý
- They did, in fact, have big guts.