あんぐり is defined as such:
adverb / noun or verb acting prenominally: open-mouthed
大学の門の前に真っ赤なフェラーリが停めてあるのを見て、アングリした。 I saw a bright red Ferrari parked at the campus gates and my jaw just dropped.
I am confused by seeing it in examples such as the following:
These examples seem redundant but why are they not? What information am I lacking that would distinguish あんぐり from 口を開けて? In English, the expression "with mouth agape," means to have one's mouth open in astonishment or surprise. It would seem to be a similar expression to あんぐり. To me the quoted examples seem redundant in meaning, but are they communicating two different things to those fluent in Japanese? Is there etymological information to the word あんぐり that would change my understanding of it? Can あんぐり mean "in astonishment/in amazement" without referring to the mouth?
In the quoted example below, it is especially the も that is throwing me off. What extra meaning does it give the sentence? Is this も an adverb meaning "more / further"? After giving it further thought, I came up with these interpretations below. Do they make sense?
あんぐりと口もひらき = "He gaped in astonishment, his mouth widening even more..." Or maybe a better translation is : " With jaw-dropping astonishment, his mouth widened even more..."