DrInsomnia
DrInsomnia t1_ja4jodn wrote
Reply to comment by DrInsomnia in For birds all sex is anal sex. by Whats-Upvote
I should add that mammals are the outlier here, having subdivided these tasks into separate orifices. Most vertebrates have a single opening, derived from embryological anal opening, which does it all.
DrInsomnia t1_ja4j8ck wrote
Reply to comment by lightknight7777 in For birds all sex is anal sex. by Whats-Upvote
Yes. And a cloaca is an anus that has taken on additional functionality in some groups. In fact, in mammals the original mammalian ancestor likely had a cloaca, which split into separate openings (in some derived groups). But embryologically it all starts with the anus.
DrInsomnia t1_ja4ifqr wrote
Reply to comment by lightknight7777 in For birds all sex is anal sex. by Whats-Upvote
There's a distinct term for it because it serves more than one function. But it developmentally starts as the anal opening, and continues to serve as the anus in an adult. This is really all semantics, but from a developmental biology standpoint it is an anus that has acquired other functionality.
Edit to add, from the Wiki link: "In deuterostomes, the original dent becomes the anus, while the gut eventually tunnels through the embryo until it reaches the other side, forming an opening that becomes the mouth."
Vertebrates are deuterostomes. In bird development, that original "anus" becomes the cloaca.
DrInsomnia t1_ja4d2fr wrote
Reply to comment by DarthPeteMitchell in For birds all sex is anal sex. by Whats-Upvote
They do have cochleas (all mammals do). But birds don't.
DrInsomnia t1_ja4cluu wrote
Reply to comment by lightknight7777 in For birds all sex is anal sex. by Whats-Upvote
This is not true. From their earliest embryological development, animals have mouth and anal openings. It's representative of the tube-like critters from which we first evolved. In some animals other orifices develop, but mouth and anus are generally present unless secondarily lost. The cloaca is an anus with additional functions, which is not uncommon in the animal kingdom.
DrInsomnia t1_ja4ppn6 wrote
Reply to comment by FooBarU2 in For birds all sex is anal sex. by Whats-Upvote
Yes. I know. That's what my comment said.