Sauroposeidon (Sauroposeidon proteles)
The Sauroposeidon was the last and most specialized giant sauropod known in North America, during the Early Cretaceous period.
Size
Palaeontologists believe Sauroposeidon could have grown to 27 - 30 meters in length, and 60 tons in weight, making it the largest animal to ever walk the Earth.
Behaviour
Sauroposeidon fed on tough vegetation using chisel-like teeth to rake leaves and needles from the branch. Sauroposeidon's long neck and high fore-limbs allowed it to feed from the highest vegetation. Like many related dinosaurs, Sauroposeidon swallowed stones (known as gastroliths) to help digest the tough material in its stomach. Scientists have found groups of footprints that show that Sauroposeidon lived in herds. It is also thought that these large herds would have spent time feeding in one place, then, as soon as there was no more to eat, they would move to another place with a fresh supply of food.
Position in Food Chain
They were the only creature in the ecosystem able to browse on the highest trees (which would have been conifers). Adults were immune from all predators in the ecosystem, but the carcass of a Sauroposeidon that died of natural causes would attract many different carnivores who would feed on it for weeks.
Habitat
Sauroposeidon would be found in open woodland, when browsing. They would migrate through large areas of open land and river plain to find new browsing or drinking areas.
Reconstruction
Sauroposeidon is known from just four bones in its neck, the articulated mid-cervical vertebrae. From these bones, Paleontologists have worked out that the Sauroposeidon is as a relative of the well-known Brachiosaurus, of which a number of complete skeletons and skulls are preserved.
Sauroposeidon's vertebrae were very tightly interlocked, and contained cavities, making its neck very strong and inflexible, yet light as well. This allowed the neck to be held high. From a side view, Sauroposeidon’s neck took on a shallow 'S'-shape curve due to the position of its muscles. At an estimated 12 meters, the neck of Sauroposeidon is the largest of any vertebrate ever.
Recreating Sauroposeidon for Earthsim
Sounds
As the largest animal in the ecosystem, Sauroposeidon probably made booming rumbling sounds, or deep honks, along the lines of, say, a blue whale. In Earthsim we have based the sounds of the large sauropods on recordings of whales.
Color
The colour of large sauropods is frequently portrayed as dull grey or brown, paralleling the condition seen in large mammals such as elephants and rhinos today. However, another large animal with a resemblance to Sauroposeidon, the giraffe, is yellow with chocolate spots, these spots work to break up the image of the creature when seen through the canopies of trees. In Earthsim we have chosen the more colourful option.
Visual Reconstruction
Sauroposeidon is known from just the four articulated mid-cervical (neck) vertebrae. Analysis of the evolutionary relationships of Sauroposeidon, ally this genus with the well-known Brachiosaurus, of which a number of complete skeletons and skulls are preserved. Brachiosaurus can therefore be employed as a guide to restoring Sauroposeidon, but there can also a degree of flexibility in our restoration.
General Dimensions
Vertebra number 8 alone is 1.4m long. This is 25% longer than the equivalent bone in Brachiosaurus, thus we have our scaling factor. The neck was at least 12 metres in length, the animal from tip to tail, about 31.25m (Brachiosaurus, 25m), total height, 20m (Brachiosaurus, 16m), shoulder and hip height, 8.5m and 6.75m respectively. Bar the neck length estimates, these figures are all our own estimates. Sauroposeidon is unusual amongst sauropods, in that the fore limbs are longer than the hind limbs. The neck is perceived to be the longest of any known vertebrate.
Skull
Teeth. The teeth are elongate, blunt ‘pegs’, Viewed from the outside of the mouth, each tooth is roughly an elongate oval, with a rounded tip. They are reasonably closely packed into the mouth, with a short gap (about 1/2 a tooth width) between each. There is a total of 30 teeth in the upper jaw (15 on each side), and roughly the same in the lower jaw, their size decreases backwards slightly, but they extend all the way to the rear of the mouth. The teeth line up along the outer margin of the jaws, and form a broad ‘U’ shape, in line with the contours of the skull from above. The teeth are visible when the mouth is open and closed, there is a rough tooth-to-tooth occlusion: when the mouth was closed the teeth of the lower jaw contacted the teeth on the upper jaw more-or-less head on. The tooth rows of the lower jaw do not extend backwards quite as far as the upper row.
Cranium
The skull width is about half the length. There is a broad blunt muzzle, with more or less vertical sides and a flat top. The nares (nostrils) are large, and are separated by a thin bony strut, which arches from just above the eyes, to the rear of the muzzle. The lower jaw is also broadly ‘U’ shaped, from above/below, a little less deep than the muzzle. There are small pits on the sides of the muzzle and jaw – 4-5 on muzzle, 6-8 on jaw. The orbit is situated at the top/back of the skull. The skull is displaced downwards behind the tooth row, so that the jaw articulation is very low, and the articulation for the neck points downwards – the angle of the head on the neck was roughly 45 degrees.
Skull: facial features
The nostrils were positioned at the very front of the nares. The rest of the nasal cavity would have been covered by skin, but the mid-line ridge would have been visible. Impressions on the top of the muzzle show that the skin of the nasal cavity may have extended far forward. The eyes were quite small and positioned far back. They were almost at a level with the nostrils. They faced outwards but would have been slightly visible from the front/above. The jaw articulation was far lower than the line of the tooth row, so where the mouth ends, the jaw-line kinks downwards to the articulation. There are large dimples/pits on the jaws above and below the teeth, (see above), these were for the passage of blood vessels, which probably supplied blood to a pair of fleshy lips. The rendering also reminded us not to forget that dinosaurs have ears (this goes for all of them), these are small openings at the rear of the skull.
Legs and posture
Front ‘feet’. The hands of Brachiosaurus were elongate and ‘stumpy’; all of the ‘fingers’ were extremely short and did not splay out. In fact fingers are more or less non-existent in Brachiosaurus. Only the first digit (thumb) bears a claw, which points inwards. All of the other digits did not have claws, and should be rendered as loosely defined, with only the indication of separate metacarpals. Also, the hands are not simple round stumps like logs, as in elephants and the hind feet of Sauroposeidon (see below). Footprints show them to have been semicircular, with a rear excavation (roughly equivalent to the palm of the hand). This is because the long-bones in the hands, form an arch in cross-section. This organisation is also borne out in the fossilised trackways of sauropod dinosaurs. Hind feet. There were 5 toes on each foot, all bearing a curved claw. The claws splayed outwards. The hind limbs supported the majority of the weight of the animal, and were held vertical. They also may have been used in conjunction with the tail to form a tripod for rearing up, to reach (even!) higher vegetation. The current rendering, in side view, is good. Viewed from above, neither the arms or the legs would have been visible, as they are both held vertical.
The ‘torso’. A notable feature in Brachiosaurus, is the elongated fourth dorsal (back) vertebrae over the shoulders, which form ‘withers’, as in many mammals. This was used as a point of attachment for the strong neck muscles which held the neck upright. In life, there would have been a rather pronounced hump in this region. The slope of the back would have tapered backwards, due to the length of the fore-limbs. The stomach would have been huge and rounded, there may have been impressions of the long stomach-supporting ribs, on the tops and side of the gut. The ribs pointed downwards and slightly backwards. Neck. Analyses of the sauropod neck, show that it was held upright in a sigmoid curve. The vertebrae are full of hollows to lighten the structure.
Skin and spines
Skin impressions are known for sauropod dinosaurs. The popular image of sauropods as elephantine and rubbery, is now out of date, these dinosaurs were scaley too. The scales are large 7cm – 10cm, and closely packed like a mosaic – not overlapping. Small rows of larger scales may have run along the long axis of the dinosaur. The skin over the majority of the body would have likely been held tight, especially around the stomach. A row of spines is known to have run along the spine in other sauropods, and it’s generally agreed that this feature was present in brachiosaurs. These spines were reasonably high triangular spines, flat from side-to-side, larger on the base of the neck and front of the back above the shoulders.
Primary references
Chiappe et al. 1998. Sauropod dinosaur embryos from the Late Cretaceous of Patagonia. Nature, 396, 258-261.
Norman, 1985. The Illustrated Encyclopedia of Dinosaurs, Crescent Books.
Martill, D. M. and Naish, D. 2001. Dinosaurs of the Isle of Wight. The Palaeontological Association.
Paul, G. 1988. The brachiosaur giants of the Morrison and Tendaguru with a description of a new subgenus, Giraffatitan, and a comparison of the worlds largest dinosaurs. Hunteria, 2, 1-14
Wedel, M. J., R. L. Cifelli, and R. K. Sanders. 2000a, Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon: Acta Palaeontologica Polonica, 45, 343–388.
Wedel, M. J.; Cifelli, R. L. and KentS. R. 2000b: Sauroposeidon Proteles, a new sauropod from the early Cretaceous of. Journal of Vertebrate Paleontology, 20, (1), 109–114.
Weishampel, W. D ., Dodson, P. and Osmólska. H. (eds.), The Dinosauria. Second Edition. University of California Press.