Did dinosaurs live in herds?

This question came from Jack on the Naked Scientists facebook page. Chris Smith put it to palaeo-zoologist Jason Head, from the University of Cambridge...

Chris - "Did dinosaurs live in herds, or on their own?" - So, were they lonesome dinosaurs, or sociable sauropods?"

Jason - We know this from a couple of different lines of evidence for different dinosaur groups. We have trackway evidence that shows that groups like Duck Billed dinosaurs and the large long necked Sauropods were moving in multiple age class groups.

So you would have adults based on the size of their footprints, and juveniles and babies based on the size of their footprints moving in the same direction, and also changing directions in the same pattern and the same orientation, which suggest the animals just weren’t going along the same direction, they were making the same turns, the same manoeuvers.

That suggests animals moving in the same direction and the same grouping. We also have a few big monospecific bone beds which are catastrophic events where you have a population of dinosaurs that is killed usually be something like a flooding event.

Very famously there’s a group of horned dinosaurs called Centrosaurus from Alberta and there’s a mass death assemblage of these animals. So hundreds and hundreds of individuals in a bone bed, in a single horizon of rock, which really looks like a large herd of animals that was killed in a flash flood event. There are modern Caribou mass death assemblages that are patterned just the same way that we see in these animals.