(ATHENS, Ohio) Scientists from the Ohio University Heritage College of Osteopathic Medicine are part of an international team describing a new dinosaur species named Sarmientosaurus musacchioi. The discovery of an essentially complete, well-preserved skull and partial neck of the long-necked dinosaur in Argentina gives scientists the first good look at the head of an anatomically primitive titanosaur. It has yielded some of the most comprehensive information to date regarding the brain and senses of titanosaurs. An article describing the discovery appears today in the journal PLOS ONE.
Lawrence M. Witmer, Ph.D., an anatomy professor, and Ryan Ridgely, a research associate at the Heritage College, who are part of a team comprised of researchers from Argentina and the U.S., helped interpret the anatomy, particularly the brain and sensory systems, after CT scans were made of the Sarmientosaurus skull and neck bones. Using three-dimensional modeling, Witmer and Ridgely showed that while the brain of Sarmientosaurus was small relative to its enormous body, its sensory capabilities outstripped those of most other sauropods, with a large eyeball and good vision and an inner ear better tuned for hearing low-frequency airborne sounds than other titanosaurs. Moreover, the balance organ of the inner ear indicates that this dinosaur probably habitually held its head with the snout facing downward, which may in turn suggest that it fed primarily on low-growing plants.
“The Sarmientosaurus skull is beautifully-preserved, which meant that we could tease out a ton of information. It was really exciting for us to work through the CT scan data because it gave us a glimpse into the biology and lifestyle of this animal like we rarely get with dinosaurs,” said Witmer, an expert in cranial anatomy.
In addition to Witmer and Ridgely, who were funded by grants from the U.S. National Science Foundation, members of the research team include the study’s leader, paleontologist Rubén Martínez, as well as geologist Gabriel Casal with the Laboratorio de Paleovertebrados of the Universidad Nacional de la Patagonia San Juan Bosco; paleontologist Matthew Lamanna of Carnegie Museum of Natural History; paleontologist Fernando Novas of the Museo Argentino de Ciencias Naturales; and Argentinian medical professionals Javier Martínez and Javier Vita.
“Discoveries like Sarmientosaurus happen once in a lifetime,” said Martínez, who found the bones in the Patagonia region of Argentina from rocks laid down during the middle of the Cretaceous Period (the third and final period of the Mesozoic Era, or Age of Dinosaurs), roughly 95 million years ago. “That’s why we studied the fossils so thoroughly, to learn as much about this amazing animal as we could.”
Despite their remarkable species richness and diversity in body size, many aspects of titanosaur anatomy, evolution, behavior and ecology are not well understood because skulls of these animals—which are fundamental for deciphering critical aspects of their biology—are exceedingly rare. Of the 60-plus named titanosaurs, scientists have discovered nearly complete skulls for only four species, including Sarmientosaurus.
“Titanosaurs included the biggest land animals ever, so we want to know as much about them as we can,” said Lamanna. “But to truly understand a creature, you need to have its head. And because titanosaur skulls are super-rare, lots of important aspects of how these dinosaurs lived and behaved have really been anybody’s guess.”
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