Sauroposeidon

Phylogeny: Dinosauria > Saurischia > Sauropodomorpha > Plateosauria > Massopoda > Sauropodiformes > Sauropoda > Gravisauria > Eusauropoda > Neosauropoda > Macronaria > Titanosauriformes > Somphospondyli

Overview: In 1994, a set of large fossil masses were discovered in southern Oklahoma. Scientists at the scene would assume these were the remains of a gigantic petrified tree, seeing them as far too large to be the bones of an animal. They were indeed bones, however, specifically a series of neck vertebrae from a massive sauropod dinosaur, sporting a longer profile than those typically seen on most other sauropods. In 2000, these fossils were used to describe Sauroposeidon as a new genus. Sauroposeidon takes part of its name from that of the Greek god Poseidon, who was seen as both the ruler of the seas and also as the cause of earthquakes, referring to the animal’s massive size. It was often cited in the media at the time as the largest dinosaur yet discovered, but this may be an exaggeration, though Sauroposeidon is counted among such animals. Length estimates put it at up to or likely over thirty meters in length, with a tremendous weight in the multiple dozens of tons. It’s very likely to have been the largest dinosaur in its environment. It had one of the longest necks of any animal, allowing it to feed from branches out of reach for even other sauropods.

The holotype specimen of Sauroposeidon was found in Oklahoma’s Antlers Formation, but fossils from other geological formations in other states have also been referred to it. This includes bones from the Twin Mountains and Glen Rose formations of Texas, as well as in the Cloverly Formation of Wyoming. Those from the Twin Mountains were once referred to a genus called Paluxysaurus, but this is now considered a junior synonym of Sauroposeidon. Referring said bones to this genus expands the known material to its limbs and other parts of the body. In many regions, large-bodied theropods like Acrocanthosaurus were present, though fully mature Sauroposeidon would’ve been tough prey for even that carnivore. Acrocanthosaurus may’ve preyed on young or sick individuals, however. Phylogenetic studies used to classify Sauroposeidon as an even more gigantic relative of the famous Brachiosaurus, within the family Brachiosauridae, but most studies nowadays classify it as more derived than Brachiosaurus. Sauroposeidon probably belonged to the Somphospondyli, so it was more closely related to the euhelopodids or even the true titanosaurs.