I am currently writing a formal piece of academic work in which I want to add a supplementary, parenthetical clause in the middle of another sentence. However, the supplemenatary clause is itself a stand-alone sentence. I don't want to bog you down with the technical guff from my work and so will illustrate with a different example:
Not only are penguins flightless birds [pause They are. pause], they are also aquatic.
Note that the example above is not a suggested format for the sentence (I am deliberately trying not to beg the question).
My question is:
- How should I punctuate the bolded parenthetical phrase in the sentence above?
I am not asking about how to reformulate the sentence to avoid thorny punctuation issues. I would like to represent this sentence exactly how I might say it in a formal presentation without the addition of any ands or other reformulations.
My concerns are:
I want to emphatically assert in my parenthetical phrase that penguins are flightless.
The parenthetical phrase is effectively a stand-alone sentence inside another sentence. So I am unsure about whether the first word should/can be capitalised.
I am unsure about any punctuation at the end of the clause before the first, larger sentence recommences.
I'm unsure about any encompasing punctuation devices I could use before and after the phrase (in conjunction with the other issues mentioned in (1-3) above.
Of course, I could easily say and they are. However, that is not the sentence I'm trying to represent in the writing. Please do not recommend the and. I'm not interested. I want the words to be exactly and only the words used in my example.