Until the recent discovery of fossilized sauropod nesting grounds, scientists were thus uncertain whether sauropods laid eggs or gave birth to live young.
因此，直到最近发现蜥脚类恐龙筑巢地的化石之前，科学家们还不能确定蜥脚类动物到底是产卵还是胎生。
Ichthyosaurs also resembled cetaceans in another way: unlike most living reptiles, which lay eggs, they gave birth to live young.
鱼龙和鲸类的另一点相似在于：不像其他目前存活的卵生爬行类，他们胎生生下后代。
Notably, the snake populations studied all give birth to live young (other species like pythons, lay eggs) and are sit-and-wait predators, making them more vulnerable to change in their environments.
值得注意的是，接受数量考察的都是卵胎生种类（另外一些种类，比如蟒蛇，则是卵生）以及静候捕猎的种类，这会让他们更容易受到环境变化带来的影响。
Notably, the snake populations studied all give birth to live young (other species like pythons, lay eggs) and are sit-and-wait predators, making them more vulnerable to change in their environments.
值得注意的是，接受数量考察的都是卵胎生种类（另外一些种类，比如蟒蛇，则是卵生）以及静候捕猎的种类，这会让他们更容易受到环境变化带来的影响。
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