Sauroposeidon, meaning “earthquake god lizard,” is a genus of sauropods dinosaur from the Aptian and Albian ages of the Early Cretaceous Period (110 million years ago). It was discovered in the southeast region of Atoka County, Oklahoma, not far from the border of Texas, in a claystone outcrop. The fossils were initially misidentified as pieces of petrified wood when they were found in 1994. A more detailed analysis in 1999 revealed they were truly dinosaurian bones. They were formally published a year later.

Sauroposeidon lived on the shores of the Gulf of Mexico in a river delta during its reign. Like other brachiosaurids, Sauroposeidon was a quadrupedal herbivore with longer forelimbs than hindlimbs, a similar body design to the modern giraffe. Based on similarities with the more completely known Brachiosaurus, Sauroposeidon may have stood 56 feet tall at the top of the head, making it the tallest known dinosaur. It had an estimated length of 112 feet and a mass of 55 to 66 tons, also making it one of the longest and heaviest.

The four neck vertebrae were discovered in 1994 at the Antlers Formation in Atoka County, Oklahoma by Dr. Richard Cifelli from the Oklahoma Museum of Natural History. The finds, initially believed to be petrified tree trunks, are the longest such bones known in dinosaurs. The fossils were formally named as type species S. proteles in March 2000.

While the media attention that came from a 1999 press release of the description of this dinosaur led many to believe it was the “largest dinosaur ever,” Sauroposeidon is really only the tallest known. There are others that are both longer and heavier. Argentinosaurus is a better candidate for the title “World’s Largest Dinosaur.”

The vertebrae of Sauroposeidon are the longest neck vertebrae on record. Examination of the bones revealed that they are honeycombed with tiny air cells, and are very thin, like the bones of a chicken, making the neck lighter and easier to lift. The largest vertebrae had an overall length of about 4.6 feet. The cervical ribs were also quite long, with the longest measuring 11.2 feet long — about 18 percent longer than the longest rib for Giraffatitan.

The total length of the neck is estimated at 37 to 39 feet, compared to the 30 foot neck of Giraffatitan. This is based on the assumption that the rest of the neck has the same proportions as Giraffatitan. Its build is also similar to the modern giraffe.

The mass estimate of Sauroposeidon, up to 66 tons, may be too high. According to some studies, Sauroposeidon may have had an air sac system, like those found in modern birds, which could reduce mass estimates by 20 percent or more.