Sauropods are the quintessential large dinosaurs. Questions about their biology and anatomy have fascinated scientists and the public alike for over a century.
While working on describing the anatomy and relationships of Supersaurus with some colleagues, I have been examining the functional anatomy of sauropods in some detail the last few years. Of particular interest is how these long-necked animals held their necks in life. Did they carry them straight out, or slanted upwards like a giraffe? Alas, publishing always takes more time than we would like, so I won't have anything specific to say until this fall. In the meantime, I've made available some information on the WDC specimen of Supersaurus, and some of the skeletal drawings I've done of other sauropods.
Apatosaurus: Numerous species of Apatosaurus have been named, but only three are considered valid: the type species A. ajax as well as the more common species A. excelsus and A. louisae. Because it turns out that Supersaurus is more closely related to Apatosaurus than to Diplodocus or Barosaurus, I have taken a particular interest in this genus. Below are skeletal reconstructions of the three commonly accepted species of Apatosaurus:
Barosaurus: Some researchers thought that Supersaurus might be closely related to Barosaurus lentus, a lightly built, long-necked diplodocid. One line of evidence for this supposed relationship was a series of very Barosaurus-like tail vertebrae that had been assigned to the original (or "type") specimen of Supersaurus from Utah. The WDC specimen of Supersaurus shows that this was a mistake, and that Supersaurus had very Apatosaurus-like tail vertebrae. What of the tail bones assigned to the original specimen? Both were found in a quarry with over a dozen different species of dinosaur, so our best guess is that they actually are Barosaurus tail vertebrae, and never should have been referred to Supersaurus.
Diplodocus: Diplodocus is the closest relative of Barosaurus. There are at least two species, Diplodocus longus and Diplodocus carnegii. Diplodocus is known for having extremely long tails, even by diplodocid standards. (See the Seismosaurus section below for more information on Diplodocus species.)
Seismosaurus: Seismosaurus was named for a very Diplodocus-like specimen from New Mexico. Although initial reports suggested that the skeleton could be up to 150 feet long (48 meters), a rigorous reconstruction based on the known skeletal elements suggests that it was unlikely that the skeleton exceeded 98 feet (31 meters). In fact, numerous studies, (including an upcoming paper by myself and colleagues) have found that Seismosaurus is likely a specimen of Diplodocus. We have gone one step further, suggesting that the "Seismosaurus" specimen is specifically a specimen of the lesser known species of Diplodocus, Diplodocus longus. Compare for yourself: