Sauroposeidon

Chapter • Meet the dinosaur

Overview

Sauroposeidon proteles ranks among the tallest dinosaurs ever found. It had the giraffe-like build typical of brachiosaurids and their close relatives: forelimbs longer than the hind limbs, shoulders held high, and a neck of extraordinary length. The neck vertebrae are the animal's claim to fame. The longest preserved one measures roughly 1.25 metres, the longest single neck vertebra known from any animal, and the complete neck is estimated at about 11 to 12 metres. Total body length is put at 27 to 34 metres and body mass at roughly 40 to 60 tonnes, although only part of the skeleton is known and the higher figures have been revised downwards in more recent studies. The vertebrae were hollowed out by air sacs in the same way as in modern birds. In places the bone walls of the neck vertebrae were only a few millimetres thick, and the vertebra as a whole was close to ninety percent air. That is precisely what made such a neck possible: enormous reach with surprisingly little weight. The internal struts also limited flexibility, and researchers still debate how high the head was normally carried. A likely picture is an animal that fed with the neck at a moderate angle, sweeping the head over a wide area of vegetation without moving its bulky body. Sauroposeidon was a plant eater whose reach let it browse foliage far above the level available to almost any other animal of its time. Its peg-like teeth stripped leaves and needles rather than chewing them; food was swallowed whole and processed in an enormous gut. An animal on this scale must have fed for a large part of the day and night, and growth studies on other sauropods suggest that juveniles grew quickly and reached adult size within a few decades. The fossils were found in 1994 by Bobby Cross in Atoka County, Oklahoma, in rocks of the Antlers Formation. The four long bones looked so much like petrified tree trunks that they sat unstudied for several years. In 2000 Mathew Wedel, Richard Cifelli and R. Kent Sanders described the animal as a new genus and species. The name honours Poseidon, Greek god of earthquakes and the sea, while proteles can be translated as "perfected before the end", a reference to its position as the last great sauropod of its North American lineage. In 2012 Michael D'Emic and Brady Foreman argued that Paluxysaurus jonesi from Texas is the same animal, which would give us far more of the skeleton but also shifts Sauroposeidon out of Brachiosauridae into the broader group Somphospondyli.

Chapter • Where it lived

Habitat

Sauroposeidon lived roughly 115 to 108 million years ago, in the later part of the Early Cretaceous (Aptian to Albian). The type material comes from the Antlers Formation of southern Oklahoma, and if Paluxysaurus is included, also from the Twin Mountains Formation of Texas. The setting was a humid coastal plain along the shoreline of the ancient Gulf of Mexico, with broad river deltas, wetlands and forests of conifers, ginkgoes and ferns. Flowering plants were spreading but not yet dominant. The same habitat was home to the large predator Acrocanthosaurus and the smaller herbivore Tenontosaurus.

Chapter • Family life

Breeding

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy