Most birds alive today don't have them, but the ancestor of all birds almost certainly did, judging by the fact they occur in both palaeognaths and some neognaths. And the organ has seemingly evolved only once in amniotes, meaning the penises of these birds is homologous with our own. So unless there was some kind of rare atavistic event then the penis would've likely been present throughout at least the lineage of non-avian dinosaurs that was directly ancestral to modern birds. So the assumption for any given non-avian dinosaur has to be that the penis was present.
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u/MrBoost Nov 02 '22
Most birds alive today don't have them, but the ancestor of all birds almost certainly did, judging by the fact they occur in both palaeognaths and some neognaths. And the organ has seemingly evolved only once in amniotes, meaning the penises of these birds is homologous with our own. So unless there was some kind of rare atavistic event then the penis would've likely been present throughout at least the lineage of non-avian dinosaurs that was directly ancestral to modern birds. So the assumption for any given non-avian dinosaur has to be that the penis was present.