It has nothing to do with if the said animal were evolving or not. Birds and Crocodilians are the only living animals of the Archosauria clade. Since birds are dinosaurs, technically they aren’t their relatives. So Crocs are the closest living relatives of dinosaurs (and birds), since they belong in the same clade and shared a common ancestor more recent than anyone else alive.
It has nothing to do with if the said animal were evolving or not. Birds and Crocodilians are the only living animals of the Archosauria clade. Since birds are dinosaurs, technically they aren’t their relatives. So Crocs are the closest living relatives of dinosaurs (and birds), since they belong in the same clade and shared a common ancestor more recent than anyone else alive.