They are cold blooded. Could they survive there? Or it doesn't matter because there is micro-climate (because of a volcano)?
Well, so, here there are choices. In the real world, there's a whole lot of evidence that dinosaurs were warm-blooded, and many had feathers.
An Antarctic environment loaded with white feathery T-rex and such might be a lot of fun.
The classic would be to handle it as a microclimate - warmed by hot springs or some such. Or, it'd be entirely appropriate in 1920s pulp to have it maintained by mysterious technologies from some unknown or bygone race.