Supersaurus

SUPERSAURUS (pronounced SUE-per-SORE-us)

Era: Late Jurassic

Order, Suborder, Family: Saurischia, Sauropodomorpha, Diplodocidae

Found in: North America (United States)

Size: 100 feet (30 meters)

Supersaurus lives up to its name, 'super reptile.' Closely related to Apatosaurus and Diplodocus, this massive herbivore was a rare sight during the Late Jurassic. Only a single shoulder bone (the scapulacoracoid), measuring nearly eight feet in length, has been discovered for Supersaurus. The scapulacoracoid of Ultrasaurus is the only one comparable in size or larger.

Additional bones from the same location, the Dry Mesa Quarry in southern Colorado, have been identified as belonging to Supersaurus. These include a dislocated ischium (part of the pelvic bone), a complete sacrum and pelvis, a lone tail vertebra, and a series of 12 connected (articulated) tail vertebrae.

If the reconstructions of Supersaurus are accurate, this colossal sauropod reached lengths of at least 100 feet and stood more than 18 feet tall at the shoulder. By extending its neck into the trees for tender young shoots, Supersaurus could stretch up to 50 feet above the ground—about the height of a fifth-story window. In comparison, Brachiosaurus could reach around 40 feet high. Estimating Supersaurus' size is challenging since only the two scapulacoracoids are definitively attributed to this genus; the other bones found cannot be conclusively linked to Supersaurus, limiting the ability to calculate its size.

The unusually long shoulder bones of Supersaurus are noteworthy because, unlike other members of the Diplodocidae family, which typically have short front legs and long rear legs, Supersaurus displayed a more giraffe-like structure, with longer scapulacoracoids and front limbs. By comparing the proportions of Supersaurus' scapulacoracoid to those of other Diplodocidae members (such as Diplodocus and Apatosaurus), scientists have concluded that this gigantic sauropod was a record-setter in both length and mass. Only "Seismosaurus" might have exceeded its length.

Supersaurus, like other enormous sauropods from the Late Jurassic period, was so large that even the largest predator of the time, Allosaurus, posed little threat. However, carnivores were always opportunistic, preying on weak or sick individuals, or targeting young sauropods separated from their herds.

Supersaurus' feeding habits were likely similar to those of other sauropods. It consumed leaves and shoots from treetops, along with ferns from the ground, feeding almost continuously. Adults must have consumed hundreds of pounds of vegetation each day. Gastroliths (or 'stomach stones') may have aided in grinding up plant material in the stomach.

The true nature of Supersaurus remains an enigma, one that can only be unraveled with further excavations at the Dry Mesa Quarry. Over a dozen dinosaur species are known from this site, each represented by several hundred bones. With such a mix of bones, many years of excavation and detailed analysis will be necessary to clarify the identity of this massive dinosaur.