There is lots of evidence that has "proved" that Deinonychus was a pack hunter, but the evidence has a counter, and there is also evidence against pack hunting.

One day, a person stumbled across a bunch of Deinonychus fossils together, feasting on a Tenontosaurus. Paleontologists thought this was evidence that deinonychuses would form a pack, and viciously rip apart larger dinosaurs. However, this could also be evidence that deinonychus would scavenge Tenontosaurus corpses, and didn't mind the fact that others were also eating.

Also, paleontologists have found that there is different sediment between the teeth of baby and adult deinonychuses, indicating that they didn't care for their kids. However, this evidence could also mean that deinonychus adults and kids ate different things, and the adult(s) hunted and brought back two different creatures. One for the baby, whose teeth might not be as developed, and one for the parent.

Another piece of evidence that shows that Deinonychus wasn't a pack hunter is the lack of fossils that are clustered together. This could be caused by a predator devouring all of the pack members, except one, because it gets too full. Also, what if maybe the all but one Deinonychus was fossilized?

As you can see, all evidence people have found as to whether or not Deinonychus was a vicious pack hunter or a small, cowardly scavenger has a plausible counter. We will likely never know if packs of deinonychuses roamed the lands, or if lone deinonychuses hunted for lizards in the underbrush. For now, it is up to your imagination. It is entirely possible that both happened. It is possible that packs were formed when deinonychuses met and there was prey nearby. They killed the prey, and then went in their own seperate directions, hunting lizards and small mammals in the bushes. Either way, they are still very interesting, and important for understanding the evolution of birds.