Dear sirs,

Would you tell me what the colored sentence below means?
This is a quotation from TIME FOR KIDS.
http://www.timeforkids.com/news/fuzzy-was-he/35321

--- Quotation ---
“Large-bodied animals typically can retain heat quite easily, and actually have more of a potential problem with overheating,” Sullivan said. “That makes Yutyrannus a bit of a surprise.”

Can I paraphrase the first colored sentence to 'and actually have more potential problems with overheating.'?
I have no idea what the second sentence means. I would like you to paraphrase it with easier English.

Hiroshi
Animals with large bodies have more trouble staying cool than animals with smaller bodies.
But the yutyrannus is (was) an exception to this rule.