We know there was a lot of variation! This Smithsonian article goes into great detail. Here’s a representative quote from one of the researchers interviewed:
“It is very unique. Most cloacas form a kind of slit. Sometimes it’s a vertical split, sometimes it’s a smiley face, sometimes it’s a sour face. This thing has a V-shaped structure with a pair of nice flaring lips, and there’s not a living group of animals that have morphology like that”.
as far as my memory serves, there is very little information for us to go off to actually know definitively. We can infer based on dinosaurs living relatives, birds, however even that doesn’t get us so far. Most birds reproduce utilizing a “cloacal kiss”, however the most basal lineages of birds, the Ratites (waterfowl) often have intromittent organs (you’ve likely heard about ducks and their corkscrew penises.) The problem here is everything is soft tissue, which just doesn’t readily fossilize. Most extent reptiles have penises of some sort (crocodilians are often used as an example since they are thought to be old evolutionarily, they have a quite large, “prehensile” organ), but again, how appropriate it is to use them as a point of reference is questionable. This podcast I enjoy quite a bit and sums up our current understanding relatively well, https://open.spotify.com/episode/7CwLRbzJRZQTRMU1FTLd1q?si=56e53f77c7aa479c
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We know there was a lot of variation! This Smithsonian article goes into great detail. Here’s a representative quote from one of the researchers interviewed:
“It is very unique. Most cloacas form a kind of slit. Sometimes it’s a vertical split, sometimes it’s a smiley face, sometimes it’s a sour face. This thing has a V-shaped structure with a pair of nice flaring lips, and there’s not a living group of animals that have morphology like that”.
as far as my memory serves, there is very little information for us to go off to actually know definitively. We can infer based on dinosaurs living relatives, birds, however even that doesn’t get us so far. Most birds reproduce utilizing a “cloacal kiss”, however the most basal lineages of birds, the Ratites (waterfowl) often have intromittent organs (you’ve likely heard about ducks and their corkscrew penises.) The problem here is everything is soft tissue, which just doesn’t readily fossilize. Most extent reptiles have penises of some sort (crocodilians are often used as an example since they are thought to be old evolutionarily, they have a quite large, “prehensile” organ), but again, how appropriate it is to use them as a point of reference is questionable. This podcast I enjoy quite a bit and sums up our current understanding relatively well, https://open.spotify.com/episode/7CwLRbzJRZQTRMU1FTLd1q?si=56e53f77c7aa479c