That other monster.....

It was a part of the "demo" for the Godzilla trailer. You know, it was only a teaser and that implies that nothing of its content necessarily would be included in the film, just like the first teaser for the 1998: a bunch of kids were at the museum as part of a school trip. They arrive at the dinosaurs exhibits looking at a big T-rex skeleton; but sunddenly ZIlla´s foot trespasses the ceiling and stomps the skeleton. That scene never happened at the actual film.