Mr. McShane
Quote 1
"A condor wouldn't come up to [a Moa's] knee. Make an ostrich look small. Twelve, thirteen feet tall. Maybe the biggest bird ever. Couldn't fly. Lived in New Zealand. Died out hundreds of years ago. Killed off by people."
"Half their size," said Susan (27.63).
Mr. McShane is telling Susan about a long extinct bird, the Moa. He tells of their great size and how men killed them off, and Susan notes that a man would be half the size of a Moa. This ancient struggle can be compared to the struggle that Susan is going through. She is allowing people who are half her size (figuratively—not literally) to make Stargirl become extinct.