I think these mass extinctions are important evolutionary agents that help shake the system loose,

and because they open up large ammounts of ecological space, they probably do allow for greater

evolutionary inventiveness than might have been poetntially possible in a situation of a really crowded world.

麻煩老師詳細(xì)剖析...greater evolutionary inventiveness than might have been poetntially possible...

沒了解這部分比較結(jié)構(gòu)。

這個(gè)比較結(jié)構(gòu)貌似復(fù)雜，其實(shí)你可以把它化簡(jiǎn)，然后就是你見過的一個(gè)結(jié)構(gòu)了。先看一個(gè)簡(jiǎn)單的例句：

Now with the help of the internet we can find more information than was posssible.

than從句省略了形式主語(yǔ)it和外置的that從句（真的主語(yǔ)）。補(bǔ)全后從句為：

than it was possible that we could find without the internet.

你的句子和這個(gè)簡(jiǎn)單的例句結(jié)構(gòu)相同，只是than從句沒用was表示過去的事實(shí)，而是用了might have been表示對(duì)過去狀況的推斷，但其結(jié)構(gòu)還是相同的，即than+be+possible. than從句的形式主語(yǔ)it和外置的that主語(yǔ)從句省略了。

我覺得目前你一個(gè)人可以補(bǔ)全你的句子了。