Cetaceans reduce the number of breaths they take during rest periods.
鲸类动物在休息时减少它们的呼吸次数.
互联网
It is not clear whether cetaceans undergo dream sleep.
鲸类动物是否经历梦睡眠还不清楚.
互联网
Missing until recently were fossils clearly intermediate, or transitional, between land cetaceans.
近期发现的化石已经可以很清晰地帮助人们了解这个问题, 以及他们之间的过渡关系.
互联网
Any of various similar cetaceans, such as the killer whale.
须鲸类;露脊鲸;长须鲸; 蓝鲸;座头鲸.
互联网
Although limited to a skull , the Pakicetus fossil provides precious details on the origins of cetaceans.
尽管只是个头盖骨, 但它却提供了研究原始鲸类动物起源的珍贵信息.
互联网
