What does ‘If she’s a feminist, then I’m a T. Rex’ mean? [duplicate]

There was the following passage in New York Times’ (October 6) article commenting on GOP Presidential candidate, Carly Fiorina under the headline, ‘If she’s a feminist, then I’m a T. Rex’:

“Her record at Hewlett-Packard — firing skilled Americans by the thousands and outsourcing their jobs to China and India, while almost running her company into the ground with an ill-advised merger — is hardly a sterling record for any sort of candidate, assuming we actually want a president of all the people rather than a modern Ebenezer Scrooge, - - This is a woman who would deny other women control over their own bodies, as well. "If she’s a feminist then I’m a T. rex.”

According to Jurassic wiki, Tyrannosaurus rex, the most famous of all dinosaurs species and commonly known as T. rex, was the largest of the Tyrannosaur family — and by extension one of the largest theropods, reaching 12 to 13 meters in length.

But what does ‘If she’s a feminist, then I’m a T. Rex’ mean? Does the writer sarcastically admit herself being anachronistic? Why should it be a T.Rex, not other monsterous or supernatural creatures, say, Moby-Dick and Godzilla?

Is this a cute turn of phrase? Could you translate “I’m a T.rex” into plain English?

All that that is saying is that she is no feminist whatsoever, being just as much of a feminist as the columnist is a giant extinct dinosaur.

That is, not at all.

It's usually best not to read too much into "If X is a Y then I'm a Z." constructions. It's merely an emphatic and humorous way of saying "X is not a Y." The more ridiculous Z is, the more emphatic the statement is.

Z (a T-Rex) isn't being compared to X (Carly Fiorina) but to the writer and then that difference is being compared to the difference between X and Y (Former CEO of HP, and a feminist). So the specific nature of Z (A large, extinct therapod dinosaur) isn't really relevant so much as how much it contrasts with the writer (presumably a human).

A T-Rex may have been chosen merely because the recent movie Jurassic World brought dinosaurs to mind. If so, and if the the writer had wanted to be more emphatic the comparison might have been "then I'm T-Rex stranded on Mars." That's even more ridiculous (And references another recent movie) and therefore the overall statement would be an even more emphatic statement of disbelief in Fiorina being a feminist.

That doesn't rule out a deeper intent by the author but at best that's uncertain unless she says otherwise.

It is a hyperbole used intentionally. The purpose of the obvious exaggeration is to attract the reader's attention to the fact that she is by no means a feminist.

• a deliberate exaggeration used for effect.
• an extravagant statement or figure of speech not intended to be taken literally, as “to wait an eternity.”

The Free Dictionary