Pelorosaurus

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

Overview: In 1850, the genus Pelorosaurus was established by Gideon Mantell, who decades earlier famously did the same for Iguanodon. Mantell used a partial set of remains as the basis for his new genus, previously studied by the renowned naturalist Richard Owen. Owen saw the bones as being those of a species in the genus Cetiosaurus, which he believed was some kind of giant, ocean-going reptile, similar in form to modern crocodiles. Mantell not only recognized that Pelorosaurus was an entirely distinct genus, but also that it was fully terrestrial, and not an aquatic reptile. Indeed, this creature is one of the first dinosaurs recognized to have belonged to the clade Sauropoda, later established in the 1870’s by the American paleontologist Othniel C. Marsh. Cetiosaurus would later follow, but confusion would persist over what remains belonged to said genus, or to Pelorosaurus. In general, the history of study for both dinosaurs has proven to be quite convoluted. Out of multiple species, it is usually found today that only Pelorosaurus brevis may be valid for this genus.

Pelorosaurus and Cetiosaurus may’ve both belonged to the Sauropoda, but modern studies tend to find they weren’t all that closely related. Cetiosaurus was a more basal sauropod, belonging to the eusauropod family Cetiosauridae. Most studies place Pelorosaurus within the neosauropod lineage Macronaria, specifically within the clade Titanosauriformes. Brachiosaurus may’ve been one of its closest relatives, with a number of scientists classifying Pelorosaurus as a fellow brachiosaurid. Its other potential relatives included Giraffatitan, Abydosaurus, Cedarosaurus, and Venenosaurus. The brachiosaurids varied in size, but some grew to be quite large, Pelorosaurus among them. Its name means “monstrous lizard”, as Mantell recognized it was a massive animal. It may’ve been well over twenty meters long, with a weight in the dozens of tons. Pelorosaurus, like other brachiosaurids, is usually reconstructed with forelimbs that were longer than its hind limbs. Combined with its long neck, this allowed Pelorosaurus to feed from branches far out of reach for other herbivores.