May you be thinking of the American Crocodile - C. acutus ?
I dont know if they' ever be called cold tolerant, but they are the only crocodile native to North America -
:I think I heard somewhere before about a crocodile titled the cold tolerant crocodile and I think it was found in a colder area in America. Does anyone have any information pertaining to that species? What is it? Or was it just a crocodile escaped. I have been curious for a long time as to if it was a new sub species of sorts or if it was just a pet that managed to stay alive in the frost. Any information would be helpful.