Many of you may have seen this already, but a new paper is out with what can only be described as a female pterosaur. This is big news, while there have been suggestions in the literature (most notably about Pteranodon) about some specimens representing males or females, this is one rather more convincing than many for the simple reason that there is an egg associated with it. That it is another Darwinopterus and a great specimen too, only adds to the interest.
The egg, sadly, lacks any trace of an embryo (though this is perhaps not surprising as obviously the egg was only about to be laid, not about to hatch) but has all the characteristics of pterosaur eggs and is the right size and shape. It also lies between the legs of the female and just behind the pelvis. That it is not in the body is not a major issue – a similar situation is commonly seen with icthyosaurs for example where decomposition leads to bloating of the body and forces out anything large and solid like a late term embryo or as in this case, and egg that’s ready to be laid.
Oddly enough the real interest in the paper lies in the head of the animal. The egg clearly points to this being a female but the head has no trace of a crest, despite other specimens of Darwinopterus having one (as you can see here for example). The strong suggestion therefore is that Darwinopterus is sexually dimorphic with males having crests and females none. The authors make a pretty good case, though a hatful of other specimens with other consistent differences in something approaching a 50:50 split would be better still.
One note of warning I would add though, is not to take this too far. Such extrapolation is fine for Darwinopterus, but I’d be very wary of taking the same basic criterion and applying it to other pterosaurs. Just as a quick example, many antelope and bovids have horns in males and females, and some can be nearly identical between the two, and in reindeer the females have antlers for parts of the year when males have none, while in most deer of course only males present antlers. I suspect it’s a matter of days before we see the first crested pterosaur specimen = male (or no crest = female) blog posts or media reports but this would be, for me, a very big assumption too far. A great start yes, but not even the end of the beginning for pterosaur dimoprhism.
Special thanks to Lu Jungchang for these special photos.