Hmmmm. Looks like the record-breaking sauropod Seismosaurus Hallorum is being downgraded as merely a very large specimen of the genus Diplodocus.
By the closing years of the 20th century, enough of the fossils had been prepared to begin the creation of an accurate skeletal reconstruction of Seismosaurus. As new teams of researchers began to compare Seismosaurus to Diplodocus, they began to suspect that some of the bones that Gillette had placed towards the middle of the tail had, in fact, been located much closer to the hips. This realization significantly shortened the animal’s overall length, from a near-record 170-foot maximum down to a “mere” 110 feet long.
More importantly, this revised interpretation eliminated several of the anatomical characters that Dr. Gillette had used to distinguish Seismosaurus from Diplodocus. Most of the characters that remained had to do with relative proportions of the vertebrae, and several researchers suggested that these were well within the range of variation one might expect in a dinosaur genus like Diplodocus.