The fact that the tuataras don't have penises makes them a useful study organism because it allows scientists to ask whether the lizards' ancestors had penises and lost them, or never had them to begin with. Now, according to new research published today in Biology Letters, the last common ancestor of all the amniotes did, in fact, have an erectable phallus, and that the modern diversity is the result of evolutionary tweaks over time (not the separate evolution of different phalluses).
Overheard at a cocktail party:
'So, what do you do?'
'I study lizard penises.'
(Score: 3, Informative) by shortscreen on Friday October 30 2015, @05:47PM
A gonopodium is pretty much the same idea as a penis. IANAB(iologist) but a quick look at wiki suggests that fish did not descend from the common ancestor of amniotes mentioned in TFS.