I think also the fact of existing Bajoran-Cardassian hybrids is a good hint that Cardassians don't lay eggs.
The evolution in my universe "perfected" my reptiles, just like our evolution "perfected" us as mammals. I didn't give it a lot of thought yet, as very little of my story takes place on Cardassia Prime, but in general reptiles on the planet are highly developed (as opposed to those species, which did not evolve and are more like lizards and turtles), so Cardassians - as the sentient lifeforms - aren't the only highly evolved reptiles (or whatever we call them).
Mar'kuu were reptiles too, and also highly evolved - I imagine they were related to Cardassians similar way dolphins or whales are related to humans.
In a Cardassian library
or in a Cardassian gallery
"Reagan, it appears, is really only an ardent unionist if the unions in question are in Poland" - Stephen King, Skeleton Crew