Episode 310 is all about Hypselosaurus, a sauropod found in the 1800s that was originally thought to be an aquatic crocodile.
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In this episode, we discuss:
- The Romer Prize session of SVP featured nodosaurids, massive crocodile muscles, and the use of gastroliths source
- The Taphonomy & Stratigraphy session of SVP featured 3,000+ Edmontosaurus bones, sauropod tracks, & regurgitalites source
- The Education & Outreach session of SVP featured interactive dinosaur lessons, field work, and lots of Augmented Reality (AR) source
- The first complete Triceratops skull found in Colorado is now at the Denver Museum of Nature and Science source
- The Natural History Museum of Utah now has the Antarctic Dinosaurs exhibit source
The dinosaur of the day: Hypselosaurus
- Titanosaur sauropod that lived in the Late Cretaceous in what is now southern France (Grès à Reptiles Formation)
- Originally thought to be 49 ft (15 m) long, but now estimated to be 39.4 ft (12 m) long and weigh 7.3 to 14.5 tonnes
- Dubious genus
- First described in 1846, but not named until 1869
- Named by Philip Matheron in 1869, Hypseolosaurus priscus
- Genus name means “highest lizard”
- Originally, Matheron thought Hypselosaurus was an aquatic crocodile (said the femur didn’t have medullary bone so it could not have lived on land like Iguanodon)
- Holotype includes a partial hindlimb and two caudal vertrebrae, and two eggshell fragments were found by the fossils
- Pierre Philippe Émile Matheron described bones from Provence, France in 1846, then formally described them in 1869
- Several specimens have been referred to Hypselosaurus (Albert de Lapparent described a caudal vertebra in 1957, Bataller described a vertebra in 1960)
- In 1993, a review of sauropods in Europe found Hypselosaurus to be a nomen dubium, because the holotype didn’t have distinguishing characteristics from other sauropods in the region, and in other regions
- That would make Hypelosaurus material to be an intermediate titanosaur
- The two eggshell fragments were spherical or ellipsoid, and Matheron proposed they were either from a large bird egg or from Hypselosaurus
- Eggs were about 1 ft (30 cm) long, which were large
- Eggs may not be Hypselosaurus
- First dinosaur eggs that we know about were found in 1859 by Jean-Jacques Pouech, a priest who also explored geology and paleontology in the Pyrenees Mountains. He wrote: The most remarkable are eggshell fragments of very great dimensions. At first, I thought that hey could be integumentary plates of reptiles, but their constant thickness between two perfectly parallel surfaces, their fibrous structure, normal to the surfaces, and especially their regular curvature, definitely suggest that they are enormous eggshells, at least four times the volume of ostrich eggs.
- He thought they were from a large bird (the term “dinosaur” was not well known at the time)
- Also, dinosaur eggshells hadn’t been found before
- Then in 1869, Matheron, who named Hypselosaurus, found the eggshells and thought they could be from a giant bird or a “hypselosaur” which he thought to be a large crocodile
- In 1877, Paul Gervais compared the microstructure of those eggshell fragments with those of different birds, tortoises, crocodiles, and geckos, to figure out what laid them
- He thought they matched tortoises, and said we couldn’t know if the eggshells were from a dinosaur “because we completely do not know the characteristics of the dinosaurs’ egg”
- In 1923, Roy Chapman Andrews from AMNH found dinosaur eggs in the Gobi Desert, which got a lot more attention than the eggshell fragments found in France
- Now the existence of dinosaur eggs was accepted, and the fragments found in France were reinterpreted to be dinosaur eggs
- Shortly after, amateur geologist Maurice Derognat collected eggshell fragments in France near Velaux and Rognac. Victor Van Straelen studied their microstructure and attributed them to Hypselosaurus
- More eggs were found in France the 1930s and in 1947 Albert de Lapparent said the eggs found in that area were all from Hypselosaurus priscus.
- Different types of egg shells have been attributed to Hypelosaurus (some had very thin shells, thought to be because of changes in vegetation or climate, or overcrowding, which led to stress, or could be laid by younger individuals, or could be different taxa)
- Now thought most likely different taxa
- Other dinosaurs that lived around the same time and place include dromaeosaurids Variraptor and Pyroraptor, ornithopod Rhabdodon, and ankylosaur Rhodanosaurus
Fun Fact: CLARITY (Clear Lipid-exchanged Acrylamide-hybridized Rigid Imaging Tissue hYdrogel) can be used to make brain tissue clear and highlight neurons. More recently it has been used in dinosaur developmental research.