Dinosaurs Dominated The Earth Thanks To A Hip Modification
A study published by the magazine Scientific Reports in which they are analyzed virtual reconstructions of sauropod dinosaurs points out that part of the evolutionary success that led them to be the largest animals that have ever stepped on Earth may have been due to a hip modification. This study, the result of the development of virtual paleontology, has been led by researchers from UNED, together with the Universidade de Lisboa and the Museo Paleontológico de Elche.
The sauropods they are one of the most popular groups of dinosaurs. They were the largest animals to have walked the earth, and the conditions that enabled them to achieve enormous evolutionary success during the Mesozoic are a recurring theme in paleontological research.
The hip of sauropod dinosaurs
A study of Evolutionary Biology Group of the UNED (GBE), lead by Daniel Vidal, researcher at UNED, together with the paleontologist at UNED, Francisco Ortega; Pedro Mocho from the Universidade de Lisboa; José Luis Sanz of the Royal Academy of Sciences; and Ainara Aberasturi, director of the Elche Paleontological Museum; Published in Scientific Reports magazine, it reveals a character that could have been a key innovation in the evolution of the group.
Sauropod dinosaurs were gigantic animals, quadrupeds, with a long tail and a small skull at the end of an also long neck. The description of new species of sauropods has revealed an enormous versatility in their feeding capacities that allowed them to exploit from the vegetation at ground level to the leaves located several meters high in the treetops. The study of these capacities is not easy from the skeletons preserved as fossils. However, the enormous development that the virtual paleontology It has allowed a new approach through the analysis of virtual models of these animals.
Study with a preserved dinosaur in Elche
In this study the skeleton, about 13 meters long, of the sauropod is used as a base Spinophorosaurus nigerensis. This dinosaur is temporarily deposited in the Paleontological Museum of Elche for study and was excavated in 2007 in Niger, in the context of the PALDES (Paleontology and Development) project. This specimen from the Middle Jurassic (about 170 million years ago) is one of the most complete and best preserved primitive sauropods known. Using advanced digitizing techniques, They were obtained three-dimensional models very high resolution of each of the more than 200 bones of the skeleton. From these models a virtual recreation of the animal, applying a series of methodological principles that minimize any preconceived notion.
Surprisingly, the virtually reconstructed animal is very different than expected. Instead of having a horizontal spine, the torso and neck are much higher than in previous reconstructions due to the morphology of the sacral vertebrae. These vertebrae, instead of having a rectangular arrangement, have a wedge of up to 20 degrees that elevates the vertebrae of the tail and those of the back and neck. In Spinophorosaurus this wedging is accompanied by long arms and a flexible neck that would allow it to feed on vegetation more than 7 meters high, positioning the neck as current giraffes do.
A key innovation in its evolutionary development
When comparing the sacrum of Spinophorosaurus with that of other sauropods, it was observed that most presented also minted sacred. Only those more primitive sauropods had rectangular profile sacs. This indicates that the wedging of the sacrum appeared early in the evolutionary history of these animals, and could represent a key innovation in their evolutionary success that had been largely unnoticed until now..
The first sauropods with rectangular sacros would have had the capacity to feed on medium-sized vegetation. However, the sauropods with a wedged sacrum acquired the ability to take advantage of the higher vegetation, a capacity that would be inherited by all their descendants. In the evolutionary history of sauropods until their extinction 66 million years ago, the sacrum never lost its wedging, so those species that evolved towards a smaller-sized feeding had to modulate the position of their head through changes in length. relative of his arms.