amniota

例句：

1. 1. Amniotes are the only animals that give birth to live young.
   无脊椎动物是唯一能够产下活体的生物。
2. 2. The amniotes are divided into two main groups: reptiles and mammals.
   无脊椎动物分为两大类：爬行动物和哺乳动物。
3. 3. The amniotes have evolved over millions of years, from their ancestral forms.
   无脊椎动物经过数百万年的进化，从它们的原始形态发展而来。