Q:

Question about the use of "that's" and the portmanteau word "tigon"

I think I've found two errors in this passage (marked as bold):

Ligers tend to have characteristics more like lions than tigers. A creature can be created that’s more like a tiger, though. This offspring of a male tiger and a female lion is called a tigon.

QUESTIONS:

I think that the phrase "that's" is superfluous and the text would be better if it was deleted.  Am I right? (But if that phrase "that's" is acceptable, then what function is it performing here?)
I think that the name of that animal was misspelled and it should have been spelled as "tiglon". Am I right?

A:

You are rather too quick to say that the name of the animal 'should' be spelled 'tiglon' (I assume that you've encountered that spelling before). Maulik has provided one reference to show that 'tigon' and 'tiglon' are both used, and Google N-grams shows that both words are used with about equal frequency. 
'that ...' is a defining relative clause - it tells us exactly which creature can be created. 'that' used in this way can be omitted in certain circumstances, this being one of them. I would retain 'that' for clarity.
By the way, the offspring of a female tiger and a male lion is a liger.

