St. Valentine link: Tyrannosaurus sex

Olivia Judson speculates on the sex life of dinosaurs.

We now have a robust understanding of how sexual pressures — the pressures to find, impress, and seduce a mate — influence the evolution of males and females. So much so that if you tell me a fact, such as the average size difference between males and females in a species, or the proportion of a male’s body taken up by his testes, I can tell you what the mating system is likely to be. For example, where males are much bigger than females, fighting between males has been important — which often means that the biggest males maintain a harem. If testes are relatively large, females probably have sex with several males in the course of a single breeding episode.

These forces are so reliable that, if only we could determine the sex of dinosaur fossils, we could begin to infer their mating habits. But alas. [...]

* * *

I know this is not really relevant here, but check out this really funny story about a pet lizard ...