Sit down for this one!
I never knew much about hyenas until I discovered them in a book I highly recommend to anyone who wants to learn more about evolutionary psychology, primatology and motherhood from a female's perspective. It's called Mother Nature, by researcher-primatologist extraordinaire Sarah Hrdy. In the book she describes how hyena moms give birth. It was a real eye-opener to say the least.
From birth hyenas — a female dominant species — get super doses of male hormones. This primes them for the aggressive lifestyle they lead but also has some bizarre side effects. Namely, their genitalia are masculinized: the clitoris grows to male proportions of around 7 inches long, making them literally look like males. Researchers have great difficulty telling them apart from actual males. But what's more — I hope you're sitting down — they give birth through it.
Yep, that's right. They give birth through what amounts to a penis! The opening is only about an inch wide and babies weigh roughly two pounds — large enough to cause problems. Moms' tissues frequently tear during delivery and maternal and infant death is common, especially among first-timers. Some babies suffocate to death during delivery.
Females also mate through through the organ — giving the guys a difficult task as they try to position themselves just right. Apparently it takes male years to perfect the positioning to be successful.
If you'd like to learn more about sex role reversal and social dominance among hyenas, this article is a good, brief introduction: Establishing dominance.