In it, one researcher hypothesized that the small body size of mammals in the Mesozoic was directly related to their nocturnality.

其中，一位究人员假设中生代哺乳动体型较小与其动直接相关。

In a 2017 study, researchers looked at more than 2400 species of mammals today and created algorithms to study the genetic transitions from nocturnality to diurnality.

在 2017 年的一项究中，究人员观察了当今 2400 多种哺乳动，建了算法来究从动到昼动的遗传转变。

And in a 2014 paper, when the researchers looked even farther back in the fossil record, they found that nocturnality evolved in vertebrates before the earliest mammals appeared, within a lineage known as synapsids.

在 2014 年的一篇论文中， 当究人员回顾更远的化石记录时，他们发现在最早的哺乳动出现之前， 脊椎动就已经进化出行性，属于一个被称为合弓类的谱系。