In Depth
When looking up what is the biggest dinosaur, people usually get presented with the image of a sauropod, but the exact owner of this title depends upon a number of factors, particularly the definition of largest be it by length, height or weight. Although incomplete, Sauroposeidon is thought to be one of the largest dinosaurs but not necessarily ‘the’ largest. It does however appear to have been one of the last of the giant sauropods alive in North America since remains are dated to the Aptian to Albian stages of the early Cretaceous. Even by this time the sauropods were rare when compared to their numbers in the late Jurassic and eventually they seem to have been replaced by ceratopsian dinosaurs and hadrosaurs as the dominant herbivores.
The first remains of Sauroposeidon were discovered in 1994 by a team led by Dr. Richard Cifelli, however at the time they were misidentified as petrified tree trunks. It was not until 1999 when Cifelli removed them from storage and passed them onto Matt Wedel for study that their real identity of being sauropod vertebrae was discovered. What really made the discovery exciting was the sheer size of the vertebrae that were some of the largest ever seen. The remains were officially named Sauroposeidon in 2000, but Sauroposeidon still made headlines towards the end on 1999 when the discovery was announced in a press release.
This sparked a short lived media sensation about the discovery of the biggest dinosaur, but as is often the case concerning stories about palaeontology, the headline got in the way of the facts. The vertebrae came from a very big dinosaur but the only clue we have to the size of Sauroposeidon is comparison to related dinosaurs with a similar body form. For this purpose palaeontologists used Giraffatitan due to it having some of the most complete remains, although a complete skeleton from a single individual is still unknown. Comparison to Giraffatitan has allowed for reconstructions of Sauroposeidon where it was capable of lifting its head to around seventeen meters off the ground, something which if accurate would place Sauroposeidon as the tallest dinosaur.
However the comparison to Giraffatitan may not be perfect because while Sauroposeidon has longer vertebrae, the overall construction suggests that Sauroposeidon was more gracile, which basically means more lightly built. This has led to speculation that Sauroposeidon may have had a neck that when compared to the size of the body, was proportionately longer than that of Giraffatitan. The cervical ribs that supported the girth of the neck also suggest that the neck was lightly built despite its large size. As such it seems that like with other sauropods, as Sauroposeidon got larger the body changed to be not as heavily built as its smaller relatives. This is a clever progression as it means the body would not require a directly proportional increase in calories to fuel a more massive body, however it also means that Sauroposeidon is unlikely to claim the title of largest dinosaur in terms of weight. At the time of writing the best contenders for biggest dinosaur are Argentinosaurus from South America, or possibly even Amphicoelias.
When fully grown Sauroposeidon was virtually ‘attack proof’ since even the largest predator known to be active in North America at the time, Acrocanthosaurus, would have probably been less than half the length and many times lighter than Sauroposeidon. However before an individual attained this size it would need to spend many years as a much smaller juvenile and here is where the danger of predators like Acrocanthosaurus would have been at its greatest. Additionally the large dromaeosaur Utahraptor was also active in North America at roughly this time and with its size advantage over other related but generally smaller dinosaurs, it could have easily killed a very young Sauroposeidon.
The name Sauroposeidon is a reference to the Greek god Poseidon, who while usually depicted as a deity of the sea, also held domain over earthquakes. With Sauroposeidon being such a large and heavy dinosaur weighing many tons, it was thought to shake the ground like there was an earthquake when it walked, hence the connection.
Further Reading
– Sauroposeidon proteles, a new sauropod from the Early Cretaceous of Oklahoma. Journal of Vertebrate Paleontology 20 (1): 109–114 – M. J. Wedel, R. L. Cifelli & R. K. Sanders – 2000. – Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. – Acta Palaeontologica Polonica 45: 343–3888. – M. J. Wedel, R. L. Cifelli & R. K. Sanders – 2000. – Sauroposeidon: Oklahoma’s Native Giant. – Oklahoma Geology Notes 65 (2): 40–57. – Mathew J. Wedel & Richard L. Cifelli – 2005. – A new titanosauriform sauropod (Dinosauria: Saurischia) from the Early Cretaceous of central Texas and its phylogenetic relationships. – Palaeontologia Electronica 10 (2). – Peter J. Rose – 2007.
