Кейінгі Бор кезеңінің жойылған өкілі - Hypselosaurus

Extinct genus of reptiles
speciesbox
| fossil range = Late Cretaceous,
| image = Hypselosaurus. png
| image caption = Holotype material including femur, tibia, fibula and vertebrae
| genus = Hypselosaurus
| parent authority = Matheron, 1869 In the spring of 1869, Matheron formally described these remains, including a partial femur, fibula and possible tibia and a pair of associated caudal vertebrae, as the holotype specimen of a new taxon, Hypselosaurus priscus. Among the bones, portions of the femur shaft are not preserved, along with a majority of the tibia, while both the fibula and vertebrae are entirely preserved. Since its original description, several specimens have been referred to Hypselosaurus. One of these, originally described in 1957 by Albert de Lapparent, includes a caudal vertebra, as well as another vertebra described in 1960 by Bataller. In 1993, a review of European sauropods stated that Hypselosaurus was a nomen dubium, and that its holotype could not be verifiably distinguished from other sauropods in the same, and many other, regions. Based on this, the material that was referred to Hypselosaurus by several other authors would have to be considered an intermediate titanosaur. In addition to the holotype skeleton, Matheron described two fragments of a spherical or ellipsoid fossil in 1869. These fragments were studied for some time by Matheron and his contemporary French paleontologists, and the only probable conclusion was that they were fragments of eggshells. The eggs were proposed to have been significantly larger than those of Aepyornis when complete, and Matheron suggested that they either were a very large bird egg, or belonged to Hypselosaurus.

Hypselosaurus was a proposed to be in length, when it was considered a crocodilian, which would have made it one of the largest of the group. However, a modern estimate as a titanosaur has put Hypselosaurus at around 39.4 feet (12 m), with a very rough weight estimate of One of the smaller titanosaurs, Neuquensaurus, measures only long.

The left femur of Hypselosaurus, at in length, is quite eroded, with both the femoral head and the distal condyles being eroded and distorted by sediment. The femur is slightly sinuous, and narrows antero posteriorly, becoming a subquadrangular oval wide and only long. The internal shaft is fairly spongey, although the internal bone is only loosely attached, and the femur clearly lacks a medullary canal. Eggs with abnormally thin shells have been attributed to Hypselosaurus priscus. Some experts have speculated that this was the cause of the species' extinction, with vegetation changes, climatic change and overcrowding being the original impetus for the shell thinning. However, there are alternative explanations for the thin eggshell not dependent on pathology. Later researchers found evidence that the eggs in question successfully hatched. Some researchers postulated that the thinner "Hypselosaurus priscus" eggshells came from different taxa than the thicker eggshells, and subsequent researchers have come to support this idea. Another potential explanation for variation in eggshell thickness is that the thinner eggs were laid by younger individuals than the thicker shell eggs laid by older individuals or that it was a consequence of natural variations of eggshell thickness within a single species. Most Hypselosaurus egg are in collections and museums in France, but an egg is on display in the Life on Earth gallery at Leeds City Museum, United Kingdom, and a rock slab with twelve eggs is on display at the Museum of Evolution in Knuthenborg Safaripark, Denmark.

Hypselosaurus has been found only in the Grès à Reptiles Formation, in the Provence region of southern France. This formation, dating to the early Maastrichtian approximately 70 mya, has provided fossils of several different groups of dinosaurs. The theropods Variraptor and Pyroraptor, both considered to be within the family Dromaeosauridae, have been found in the Grés á Reptiles Formation, in addition to the nodosaurid ankylosaurian Rhodanosaurus (a dubious genus); a bone fragment potentially belonging to Abelisauridae; and the rhabdodontid ornithopod Rhabdodon. In addition, a new titanosaur, Atsinganosaurus was described from the formation, based on several dorsal vertebrae. There are also indeterminate crocodilians known from the same strata as Hypselosaurus, although they are only represented by unnamed fragments.