Okay I never post but here's to settle some stuff.
First of all,
bird penis: it's often
vestigial. Which means
it was there and
now doesn't serve evolutionary purpose in most species (with a few exception like ostriches). Such phenotypical traits are often
observable on embryos which begin to develop them but don't finalize that process. That seems to indicate that a
common ancestor of today's birds did possess a functioning penis.
1
As for dinosaurs, though
everything we have is speculative- so is everything we know about their eating habits, behaviour, everything that's not been turned into a canvas for rock to occupy, which means a lot. But guess what, that's the
rule for
every study of past phenomena2, it works by
probabilistic inference. Which means studying certain
anatomic peculiarities of dinosaur species,
comparatively to other species (? closest relatives, ergo crocodilians and birds) and with knowledge of the rules of
biology and an understanding of the intertwining of bodily characteristics, we can
formulate answers that are
more probably true than others.
To get a clear idea, one would have to look into complex scientific litterature, and even a nerd like me doesn't have the time for that :v. Here's a (very) few examples though
3, with fairly accessible stuff. But one thing you could do is look at either meta-studies or, since we're all laymen here, vulgarized articles. Here's a few:
The Anatomy of Dinosaur Sex - The Smithsonian, Riley Black
Everything You Wanted to Know About Dinosaur Sex - The Smithsonian, Riley Black (google em)
Those also contain more scientific references in description.
So what are the conclusions? Well based on the stuff I brought up above, plus advances in terms of sexual differenciation (in what is essentially animal-ish rocks), and stuff looking at the structure of eggshelves, hips and such, there's a answer that seems to be rather well accepted and that actually suits the go-to for most internet artists:
Dinosaurs likely had a
cloaca, with
internal testicles and a
retractible penis, with built-in muscles used to erect it.
Size is subject to debate, probably in between a bird and crocodilian proportion (so not too big actually).
Females have an
internal oviduct and only one cloacal opening as well. So here you go:
Cloaca + Retractible penis + Inner balls + No vagina
Thanks for reading, y'all
1
- Brennan, P.,
Birkhead, T., Zyskowski, K., Van der Waag, J. and Prum, R. O. 2008.
Independent evolutionary reductions of the phallus in basal birds. Journal of Avian Biology, 39
2
- Tucker, A., 2004,
Our knowledge of the past: A philosophy of historiography, Cambridge Press
3
- Carpenter, K., 1999,
Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction, Indiana University Press
- Brennan, P.
, Prum, R., McCracken, K., Sorenson, M., Wilson, R., & Birkhead, T., 2007,
Coevolution of Male and Female Genital Morphology in Waterfowl, PLoS ONE, 2
-
ISLE, T. E., 2012,
The socio-sexual behaviour of extant archosaurs: Implications for understanding dinosaur behaviour, Historical Biology, 21
