"You want to stick your finger in a dinosaur brain?" asked Simba Srivastava.
Surrounded by cabinets full of ancient bones in the paleobiology lab, the Virginia Tech undergraduate student held out a lumpy, pockmarked fossil.
"This is a uniquely sucky specimen," said Srivastava. "It's so bad. Like, if you saw a human skull in this way, you'd throw up."
Nevertheless, the senior geosciences major spent two years unscrambling the ancient creature and determining its place in the story of evolution. His findings, which were published today in Papers in Palaeontology , shed light on how dinosaurs dominated the Jurassic period.
This is the type of work a long-tenured curator or a late-stage professor would do, but geobiologists Sterling Nesbitt and Michelle Stocker tapped Srivastava when he was a first-year student.
"We want undergraduate researchers to experience the whole paleontological research process at Virginia Tech," said Nesbitt. "Simba grabbed the project by the reins."
Dino domination
The mangled skull was uncovered twice: In 1982, a crew from the Carnegie Museum of Natural History unearthed it from New Mexico's Ghost Ranch. Thirty-some years later, Nesbitt dug it out of a drawer and eventually brought it back to Blacksburg. Using computed tomography scanning data, Srivastava isolated the specimen digitally and 3D printed a reconstruction.
The skull belonged to a species of meat-eating dinosaur that's more than three times as old as Tyrannosaurus Rex.
These creatures lived at the end of the Triassic period, which is about 252 million to 201 million years ago. Back then, dinosaurs weren't the all-powerful apex predators portrayed by Hollywood. They were vying for resources against the forerunners of crocodiles and mammals.
But that all changed drastically when an extinction seemingly wiped out most of the competition. With that, the Triassic ended, and dinosaurs came into their power.
"Dinosaurs go from being co-stars to the headliner," Srivastava said.
Clues about how dinosaurs evolved and spread in the succeeding Jurassic period lie buried in the rocks, but well-preserved fossils from the end of the Triassic are rare.
In fact, Srivastava's squished specimen is the only one of its kind anyone has found so far.
The skull shows that the species had massive cheekbones, a wide braincase, and probably a short, deep snout. It was the first time these characteristics had been seen in early dinosaurs, indicating that they were constantly evolving, according to the study.
Murder muppet's last stand
The name Srivastava picked for the new species reflects its bizarre proportions and unfortunate condition.
"We landed on Ptychotherates bucculentus, which means 'folded hunter with full cheeks' in Latin," said Srivastava. "One paleo-artist said that it looked like a murder muppet."
After two years of deep research, the Virginia Tech team was able to determine that the skull belonged to one of the last surviving members of one of the earliest-evolving families of carnivorous dinosaurs called Herrerasauria.
Thanks to this fossil, the group made another, somewhat surprising discovery.
Ptychotherates was found in rocks that may date to right before the great extinction at the end of the Triassic period — and no other members of their family was ever seen again, possibly 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 something that wiped out not just the competitors to dinosaurs, but some long-standing dinosaur lineages themselves," Srivastava said.
And finally, because no herrerasaurians have been found anywhere else this late in the Triassic, the area that is today the American Southwest may have been where they survived the longest and made their last stand.
Srivastava's folded hunter is their only spokesperson.
"This specimen, it fits in my hands, but it is the only proof that any of these dinosaurs lived this long, lived in these latitudes, the only proof that they evolved to have this skull shape," said Srivastava. "All these billions of individuals that existed through time are spoken for by this one specimen."
Original study : DOI 10.1002/spp2.70069
