“Do you want to stick your finger in a dinosaur’s brain?” asked Simba Srivastava.
In a paleontology lab lined with cabinets of ancient fossils, a Virginia Tech undergraduate holds up a rough, hole-filled skull.
“This is a uniquely disgusting specimen,” Srivastava said. “It’s so gross. I feel like I’m going to throw up when I see a human skull like this.”
Despite its poor condition, the senior earth science major spent two years carefully reconstructing the fossil and figuring out where it fits into the evolutionary history of dinosaurs. His works are paleontology papersprovides new insights into how dinosaurs established their dominant position during the Jurassic period.
Although this type of research is usually done by experienced scientists, geobiologists Stirling Nesbitt and Michelle Stocker brought Srivastava on to the project as a first-year student.
“We want our undergraduate researchers to experience the entire paleontology research process at Virginia Tech,” Professor Nesbitt said. “Simba has taken the reins of the project.”
Restored rare dinosaur skull
This fossil had an unusual history. It was first discovered in 1982 by a team from the Carnegie Museum of Natural History at Ghost Ranch, New Mexico. More than 30 years later, Nesbitt rediscovered it in a drawer and brought it to Virginia Tech for further study.
Srivastava used computed tomography scan data to digitally separate the shattered bones and create a 3D-printed skull reconstruction.
The fossil belonged to a species of carnivorous dinosaur that lived more than three times before humans. tyrannosaurus rex.
These animals lived near the end of the Triassic period, which lasted from about 252 million to 201 million years ago. At that time, dinosaurs were not yet the dominant predators often seen in movies. They competed with crocodiles and early relatives of mammals for survival.
How did dinosaurs come to power?
After mass extinction wiped out many of their competitors, the balance changed dramatically. At the end of the Triassic period, dinosaurs quickly became the major land animals.
“Dinosaur goes from being a co-star to being a headliner,” Srivastava said.
Fossils from this important transition period are rare, especially well-preserved fossils from the end of the Triassic. That makes this damaged skull particularly valuable.
In fact, no other specimens similar to this have been found.
Even in its distorted state, the fossil revealed important details. This dinosaur had large cheekbones, a wide brain shell, and probably a short, deep snout. These features have never been seen before in early dinosaurs and suggest that they evolved in a more complex way than previously understood.
strange looking new species
Srivastava named the new species based on its unusual appearance.
“We landed at Ptychoterates Buculentus, which in Latin means ‘folded hunter with bulging cheeks,'” Srivastava said. “An antiquarian said it looked like a murderous Muppet.”
After years of analysis, the researchers determined that the dinosaur belonged to the herrerasaurids, one of the earliest groups of carnivorous dinosaurs. It appears that he was the last surviving member of this lineage.
Reconsidering the end-Triassic extinction
The fossils yielded another unexpected conclusion.
Pterosaurs were discovered in rock formations thought to date just before the end-Triassic mass extinction, and no other members of the group have been found since then, potentially suggesting that this dinosaur group went extinct as a result of that mass extinction.
“This forces us to reconsider the impact of the end-Triassic extinction as one that wiped out not only dinosaur competitors but also long-standing dinosaur lineages themselves,” Srivastava said.
Because herrerasaurs have not been found anywhere else this late in the Triassic, scientists believe that their final refuge may have been in what is now the American Southwest.
One fossil, an entire lost lineage
Srivastava’s Folded Hunter may be the only remaining evidence of the group’s final chapter.
“This specimen, which fits in my hand, is the only evidence that these dinosaurs lived this long and at this latitude, and is the only evidence that they evolved into this skull shape,” Srivastava said. “All the billions of individuals who have existed throughout the ages are represented by this one specimen.”
