Blue whales are considered the biggest animal ever lived with maximum confirmed length nearing 30 meters. While some titanosaurs reportedly were somewhat longer (up to 40 meters for Argentinosaurus and up to 37 meters for Patagotitan). It's obvious that size constitutes not just length, but I don't quite understand how one can be certain that the said sauropods were smaller provided that they are about 1.5 times longer?