Board Thread:Monster Discussions/@comment-26850821-20160401141907/@comment-26850821-20160402224053

So, if the tail by itself is 78 m long, he can't be 90 m long in total because his head + torso would be just 12 m long.

A quick pixel-scale of the style guide dimensions I showed in the OP shows that Zilla Jr.'s tail is in fact ~78 m long according to the image, which is consistent with the official guide.