Komodo dragons are solo hunters, and effective ones at that. An adult can bring down victims 10 times its own bodyweight. These reptiles are also eager scavengers, and when one of them kills a large prey item, others are likely to come running. What follows is a gruesome feeding frenzy, with a dozen or more Komodo dragons mobbing the carcass. Such meetings get violent fast. While squabbling over a corpse, Komodos may attack one another; sometimes, they even kill and eat their smaller competitors at the site.
So when paleontologists find a large collection of theropod bones and/or teeth in the same fossil deposit, what should they make of it? Should they interpret the remains like a wolf-style family unit? Or should they be viewed as the site of a disorganized mob, where side-squabbles and cannibalism would've been rampant?
For their part, Brinkman and Roach find the latter scenario more probable. "Deinonychus [and other non-avian theropods] were most likely solitary hunters who engaged in antagonistic, Komodo dragon-like feeding aggregations," Brinkman says, "and ... they interacted with each other in ways that were much more contentious, combative and cannibalistic than has widely been believed."
Finding teeth and bones together is one thing, but what about dinosaur footprints? Can they shed any light onto the pack-hunting debate? In 2007, a 120-million-year-old dromaeosaur trackway was discovered in China. Six different sets of parallel tracks — each made by an animal standing about 4 feet (1.2 meters) tall at the hip — were found. And judging by the nature of the sediment, it looks like these prints were all laid down within a very short span of time.
Anthony J. Martin, a leading paleoichnologist (a "trace fossil scientist") at Emory University, thinks the animals who made them were traveling in some kind of group. "The trackways show these dromaeosaurs were moving at about the same pace, in the same direction (parallel), and spaced more-or-less the same distance [apart]. So I'm fairly certain that this is evidence of group behavior," he says via email.
Still, this doesn't necessarily mean the dromaeosaurs hunted in packs. Maybe they were rushing toward a dead body like those independently minded Komodo dragons. In order to confidently cite any footprint assemblage as the product of pack-hunting or a similar activity, we'd need "more evidence, such as tracks of a prey animal that was clearly preceding them, and not by much time," says Martin. "Best of all would be the dromaeosaur tracks ending at a kill site. An ichnologist can dream, right?"