# Dinosaur cloaca **URL:** \ **Category:** Factual Questions\ **Created:** [January 1, 2010, 12:45am UTC](https://boards.straightdope.com/t/dinosaur-cloaca/523242 "2010-01-01T00:45:21Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Doubting\_Robert](https://avatars.discourse-cdn.com/v4/letter/d/e495f1/32.png) [@Doubting\_Robert](https://boards.straightdope.com/u/Doubting_Robert)\ **Post date:** [January 1, 2010, 12:45am UTC](https://boards.straightdope.com/t/dinosaur-cloaca/523242/1 "2010-01-01T00:45:21Z")
As Cecil explained in [http://www.straightdope.com/columns/read/2357/how-did-dinosaurs-have-sex](http://www.straightdope.com/columns/read/2357/how-did-dinosaurs-have-sex) , the urinary, digestive, and reproductive tracts of dinosaurs meet in a chamber called the cloaca, from which the appropriate excretions and secretions leave the body. My question: is the actual opening also called the cloaca, or is it something else, such as cloacal opening, anus, or anal opening? I’m writing a short story which is narrated by a palentologist, and I need to make him sound like he knows what he is talking about. Forgive me if I do not acknowledge any answers right away. I am about to log off until tomorrow (or later). Robert ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [January 1, 2010, 12:53am UTC](https://boards.straightdope.com/t/dinosaur-cloaca/523242/2 "2010-01-01T00:53:22Z")
“Cloaca” applies to both the chamber and the opening. However, the opening is also referred to a the “vent” in birds and reptiles. You could use either term. ---
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [January 1, 2010, 1:22am UTC](https://boards.straightdope.com/t/dinosaur-cloaca/523242/3 "2010-01-01T01:22:52Z")
To be completely accurate, unless there’s some fossil with soft tissue preserved that I have not encountered, we do not know what the urogential-excretory outlet(s) of dinosaurs in the classic sense (Ornithischia and non-avian Saurischia) were. However, the surviving dinosaurs (Aves) the other surviving archosaurs (Crocodylia), and the other reptle-grade surviving forms (lizards, snakes, turtles, tuatara) all have cloacas, as do the Monotremes (hence their name). So it is a very reasonable conclusion that dinosaurs had them as well. But, of course, it’s not proven. ---
**Author:** ![Doubting\_Robert](https://avatars.discourse-cdn.com/v4/letter/d/e495f1/32.png) [@Doubting\_Robert](https://boards.straightdope.com/u/Doubting_Robert)\ **Post date:** [January 1, 2010, 6:15pm UTC](https://boards.straightdope.com/t/dinosaur-cloaca/523242/4 "2010-01-01T18:15:41Z")
Colibri, thank you, that is what I needed to know. Polycarp, I already made that assumption, and I’m hardly the first. Read Cecil’s column referred to in my original post. Robert ---
**Author:** ![Doubting\_Robert](https://avatars.discourse-cdn.com/v4/letter/d/e495f1/32.png) [@Doubting\_Robert](https://boards.straightdope.com/u/Doubting_Robert)\ **Post date:** [January 1, 2010, 11:27pm UTC](https://boards.straightdope.com/t/dinosaur-cloaca/523242/5 "2010-01-01T23:27:44Z")
**Polycarp** , I’m sorry. What I said to you was rude. Your answer was correct, but it was not the answer to my question. Robert ---
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [January 2, 2010, 12:46am UTC](https://boards.straightdope.com/t/dinosaur-cloaca/523242/6 "2010-01-02T00:46:10Z")
> [@Doubting\_Robert](#): > > **Polycarp** , I’m sorry. What I said to you was rude. Your answer was correct, but it was not the answer to my question. > > Robert It’s no problem, and I took no offense. **Colibri** had already answered the question quite well; I supplemented it with the point that it was an almost-certain assumption, not something definitively known to have existed, for anyone who might otherwise draw an erroneous conclusion.