Dear sirs,

Would you tell me what the colored sentence below means?
This is a quotation from TIME FOR KIDS.

--- 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.'?
And I have no idea what the second sentence means. I would like you to paraphrase it with easier English.

Thank you in advance.

If you are using the sentence as a direct quote, you really should leave it as is. If you are using the information as a general statement, then you could rephrase it.

EX: Large-bodied animals typically can retain heat quite easily; they can potentially have problems with overheating. (The way I phrased it, I am saying that since large-bodied animals retain heat, they are more likely to have problems with overheating.
Hiroshi“That makes Yutyrannus a bit of a surprise.”
This sentence means that this particular species of animal is surprising to researchers because of its ability to overheat. For native English speakers, this sentence makes sense grammatically. There really isn't any need to rephrase the sentence because it's implied that Yutyrannus' abilities are surprising.

Hope this helps!
HiroshiAnd I have no idea what the second sentence means. I would like you to paraphrase it with easier English.
Animals with large bodies can have a problem keeping cool.
However, the yutyrannus was apparently an exception to this rule.
Students: Are you brave enough to let our tutors analyse your pronunciation?
Mr. Anonymaous,

Thank you for your advice.
I was able to understood the second advice.

But regarding the first question, I wanted to ask about the use of 'more of a potential problem'.
I have no idea why the sentence is not 'more potential problems'
Are there any different nuance between 'more of a potential problem' and 'more potential problems'?

"More [potential] problems" can refer to a collection of separate problems. A has more [potential] problems than B.

"More of a [potential] problem" refers to one single problem. A is a more serious [potential] problem than B.

The distinction between a problem and a potential problem doesn't enter into the difference between the two versions.

I suspect the author specifies potential problems because some large animals (eg. polar bears) would not encounter situations which might overheat them -- except perhaps in zoos.

In a different context, "more of a potential problem" could be used to contrast "a problem" with "a potential problem."
A is a problem all the time, but B is only a potential problem.
That is, B can become a problem only under certain specific conditions.