T. rex—hunter or scavenger? In this day and age of social freedoms, why not choose both? Because studying dinosaurs, especially fierce, glamorous ones like Tyrannosaurus rex, leads to fame and—well, if not fortune, then at least movie deals.

A study published this week in the Proceedings of the National Academy of Sciences determines, due to dental data, that T. rex was definitely a hunter.

In the Hell Creek Formation of South Dakota, researchers discovered a fossilized spine of a plant-eating hadrosaur that had an odd bone growth. Examining the fossil with a CT scan, the researchers found a tooth—belonging to a T. rex—within the bone. In fact, the bone had grown around the tooth.

“Lo and behold, the tooth plotted out just exactly with T. rex—the only known large theropod from the Hell Creek formation,” exclaims study author David Burnham of the University of Kansas. “We knew we had a T. rex tooth in the tail of a hadrosaur. Better yet, we knew the hadrosaur got away because the bone had begun to heal. Quite possibly it was being pursued by the T. rex when it was bitten. It was going in the right direction—away. The hadrosaur escaped by some stroke of luck.”

T. rex teeth had previously been found in the fossilized bones of a young ceratopsian (Triceratops or one of its kin), but there was no evidence to conclude whether the ceratopsian was alive or dead when the T. rex made a snack of it. The hadrosaur’s escape provides evidence that T. rex was a dangerous, if not always accurate, predator, according to the study’s authors.

Because T. rex regularly shed its teeth, the dinosaur went away hungry, but otherwise no worse for the encounter. It would have grown a new tooth to replace the one left behind in the hadrosaur’s tail. This could have been a typical example of T. rex’s hunting efforts, even if it didn’t result in a meal.

But the story doesn’t end there. Just because you hunt doesn’t mean that’s how you find all your meals, and most scientists agree that T. rex was likely an opportunistic scavenger, too. In fact, researchers and science writers that focus on dinosaurs are tired of the either-or question. “Whether or not T. rex hunted is the most-asked question I get at talks and on the radio. And that makes me sad,” tweeted Brian Switek Monday in response to this study. There are so many more exciting questions in the field, posted paleontologist John Hutchinson, in his blog response to the publication.

So we’ll put it to rest here… T. rex: hunter and scavenger.

Illustration by Robert DePalma II

The authors of the paper sequenced the entire genomes of five members of each of the following hunter-gatherer populations: forest-dwelling, short-statured Pygmies from Cameroon, and click-speaking Hadza and Sandawe individuals from Tanzania.

The fascinating findings tell us more about human origins and prove to be a bit controversial, so I wanted to get more information from the Academy’s expert in human evolution, Zeray Alemseged. Zeray’s studies of early human remains have been published in prominent journals and garnered him worldwide attention. (PBS’s NOVA filmed an extensive interview with him here last spring, in addition to being on the covers of Nature and National Geographic.)

Zeray says these populations are not well studied and their isolation offers a new view on the human genome. Their unique diets, stature and culture also enable scientists to potentially link specific attributes to genetic markers, he adds.

The researchers used an in-depth method that involves sequencing each strand of DNA more than 60 times on average. This redundancy makes the sequencing highly accurate, giving the geneticists confidence that any mutations they identify are real and not errors.

Their results suggest that different human populations evolved distinctly in order to reap nutrition from local foods and defend against infectious disease. They also identify new candidate genes that likely play a major role in making Pygmies short in stature.

Scanning these sequences, the researchers found 13.4 million genetic variants or mutations—locations in the genome where a single nucleotide differed from other human sequences—and astonishingly, 3 million are new to science.

These new variants can represent the gene expressions unique to these populations, Zeray explains. This study is quite significant in making these genetic links to function and attributes that are phenotypic.

Zeray reminds us that these genetic studies aren’t just for mapping our ancestry, but also for mapping our future. He offers two separate examples—first, personalized medicine could tailor to specific gene regions. Second, “If we can link variants to diet, isolation and environment,” Zeray says, citing this current study’s examples, “then we can also understand what future climate change might look like for our species and how to prepare for it.”

Finally, the study finds genetic evidence that these direct ancestors of modern humans may have interbred with members of an unknown ancestral group of hominins. Zeray remarks that this particular finding—of a potential new species—reminds us why, in this technological age, paleoanthropology is a transdisciplinary endeavor requiring both fossil discovery AND genetic research.

So he’ll wait for more evidence, along with the rest of us…