Huà / shí / xiǎn / shì / Shǐ / xīn / shì / shí / qī / xǔ / duō / bǔ / rǔ / dòng / wù / kāi / shǐ / kuài / sù / fā / zhǎn

化石显示，始新世时期许多哺乳动物开始快速发展。

Fossils show that many mammals began to develop rapidly during the Eocene.