In fact, some fossil formations, like the Jehol group in China, preserve lots of different birds and pterosaurs together, each of which ate slightly different things in slightly different environments.

事实上，一些化石地层， 如中国的热河群，将许多不同的鸟类和翼龙保存在一起，每一种都在略有不同的环境中吃略有不同的东西。