Hypselosaurus

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Hypselosaurus (meaning “highest lizard”) is a dubious genus of titanosaurian sauropod that lived in southern France about 70 million years ago, in the early Maastrichtian stage of the Late Cretaceous. It was named by Matheron in 1869. The type specimen includes a partial hind limb and two tail vertebrae, and eggshell fragments were found with the bones. Because these eggs were found nearby, many later researchers assigned large eggs from the same area to Hypselosaurus, but the eggs vary, and they probably come from different dinosaurs, so the exact identity of Hypselosaurus remains uncertain.

Today Hypselosaurus is thought to be a medium-sized titanosaur, roughly around 12 meters (about 39 feet) long, with a weight of several tons. The preserved leg bones lack a medullary cavity and show a spongey interior; the tibia and femur are incomplete and eroded. The tail vertebrae are procoelous (front ends concave, back ends convex).

Hypselosaurus is known from the Grès à Reptiles Formation in Provence, a site that also yields remains of other dinosaurs, including the dromaeosaurs Variraptor and Pyroraptor, the ornithopod Rhabdodon, and the ankylosaur Rhodanosaurus. A second titanosaur, Atsinganosaurus, was described from the same formation.

Because the holotype is not clearly distinct from other sauropods, many scientists regard Hypselosaurus priscus as a nomen dubium. Some eggs previously attributed to Hypselosaurus may belong to different taxa or reflect variation within a population. Nevertheless, Hypselosaurus remains an interesting example of a Late Cretaceous sauropod from France.