What constitutes a long intromission?

长时插入有多长？

And that along with short intromission times may be why our baculum was lost to history.

而且随着插入时间的缩短，我们的阴茎骨消失在了历史长河中。

Baculum length in primates is closely correlated with intromission time, which is how long the penis is inside the vagina.

灵长类动物阴茎骨的长度与阴茎内插时间密切相关，也就是阴茎在阴道内的时间。