The title says it all, but this episode has everything Rachel loves: phylogeny, prehistoric Kansas, evolution, physiology, and (duh) dinosaurs--but all through the lens of the evolutionary history of copulation through penises. Duck penises are even cooler than you thought. Here's what we know about dinosaur sex.
Dawn of the Deed: The Prehistoric Origins of Sex
Dawn of the Deed on Amazon; by John A Long
Here's an article on Live Science that interviews the author and others in this field. They discuss Heinrich Mallison's computerized dino sex models. The Times interviewed him too, so if you have a subscription you should check that out. (I did not. :c)
Sato, Tamaki & Cheng, Yen-nien & Wu, Xiao-Chun & Zelenitsky, Darla & Hsiao, Yu-fu. (2005). A Pair of Shelled Eggs Inside A Female Dinosaur. Science (New York, N.Y.). 308. 375. 10.1126/science.1110578.
Ratite (Ostrich) Erectile Function
Ostrich penis clears up evolutionary mystery: Overlooked bird organ is similar to, but separate from, that of reptiles and mammals. (Nature)
Brennan, P.L.R. and Prum, R.O. (2012), The erection mechanism of the ratite penis. J Zool, 286: 140-144. doi:10.1111/j.1469-7998.2011.00858.x
Crocodilian Erectile Function
Penile Anatomy and Hypotheses of Erectile Function in the American Alligator (Alligator mississippiensis): Muscular Eversion and Elastic Retraction. D.A. Kelly, 13 February 2013. Anat. Rec., 296: 488-494. doi:10.1002/ar.22644
Figure 1. Lateral view of an isolated American alligator (Alligator mississippiensis) penis showing the locations of the crurae, shaft, and glans. The ischium is sketched in to show the relative position of the penis relative to the pelvis when retracted; left is rostral, right is caudal. Scale bar = 2 cm.