Most people who have read even a little on dinosaurs at some point will have seen a photo, cast, model or reconstruction of the famous fighting dinosaurs (and if not, then follow the link to see them). However, while this fascinating fossil certainly tells us that at least one Velociraptor took on a Protoceratops this is pretty much the limit of our knowledge of their interaction from the fossil record. Protoceratops is by far the most common herbivore in the fossil record in which it is found (and of course close relativels like Magnirostris) and Velociraptor (or perhaps rather these days velociraptorines thank to thinks like Tsaagan and Linheraptor turning up) the most common predator. Although the two are quite similar in size, the abundance of both and the abundance of fossils would suggest that the two would have some sort of trophic relationship. i.e. the carnivore would be eating the herbivore in some way at some point.
Naturally one would expect a small predator like Velociraptor to target small prey (like juvenile Protoceratops perhaps) but that hardly rules out their taking the odd swipe at elderly or ill individuals or of scavenging from carcasses. If that was the case, then were is the evidence? Tantalisingly the famous CCDP (Chinese-Canadian Dinosaur Project) team reported often finding velociraptorine teeth with the bones of ornithischian dinosaurs, but without saying which ones they were, so while Protoceratops is the most obvious candidate we can’t say for sure. However, my new paper (you saw this coming, right?) describes a better association – velociraptorine teeth in association with a Protoceratops skeleton and feeding traces to boot.
I’m quite pleased with this work if only because it’s the first paper based on something I found and then wrote up which is rather nice. Credit must go to coauthors Jonah Choiniere and Mike Pittman who originally found the teeth and brought them back to camp. I had the bit of info on the CCDP report in my head and had been thinking about bite marks at the time, so after some pestering they took me to the site and together with Corwin Sullivan we started to sort through all the bone fragments to look for any with bite marks on them. Despite the intensive weathering of the bones, there were some pieces with drag marks from small teeth so we collected what we could and took it back to Beijing.
This paper reports on these finds and as noted above it consists of a couple of dromaeosaur teeth found in association with various bones with some of those bones bearing trace marks. I won’t labour the details, since it’s all in the paper, but I would like to talk about the implications here – are the fighting dinosaurs a one off, or did Velociraptor regularly go after Protoceratops.
As noted above the two animals are similar in length though of course in terms of build and body mass, the Protoceratops would have been the far bigger animal. That suggests that the dromaeosaurs would be unlikely to want to tackle something that big. Those who immediately want to leap and cite the fighting dinosaurs will hit two problems, first and most obviously, this is a single record of a single incident and it’s hard to say if it’s unique or not. Perhaps the Proto was already ill or injured, or the dromaeosaur was desperate, or who knows what. Secondly, big though the Protoceratops is in the fighting dinos pair, it’s actually probably not an adult and is only about 2/3rd adult size, so may have been a more tempting target for a predator (if obviously not a small juvenile).
Protoceratops teeth recovered at the site of our new record are pretty big and there were some fragments of big bones and over a big area suggesting these were the remains of a hefty animal. This would have been quite a challenge for a dromaeosaur to try and bring down. Even if it had, how much could it eat? The bite marks we found were on areas of bone associated with the jaws, hardly the most flesh-rich of areas, and there were multiple repeated bites. Why was this happening?
The conclusion we offer is that this is the result of scavenging. It’s unlikely a dromaeosaur could bring down such a big Protoceratops. Even if it did, there’d be tons of meat available on the legs and belly and the tail – there’s no need to go and scrape off what little lies on the jaws. Hell, even a whole group would probably get enough food from an animal that big without having to start chewing on the scraps on the face to the degree that they leave so many small marks on the bones. In short, this really looks like a dromaeosaur came across a corpse and scraped off it what it could (a meal is a meal) losing a couple of teeth and making some scrapes on the bones in the process. While this doesn’t support the idea of dromaeosaurs tacking big protoceratopsians for food, it does provide evidence that the former were probably feeding on the latter, even if that largely consisted of scavenging. Still, while such a relationship might be expected, it’s always good to find new information to support ideas and further understanding of the problems.
Astute readers will have noted that the paper is not actually out yet. However, the journal in question released the proofs version early and the media have picked up on it. I did check with the journal and as far as they are concerned there’s no embargo on it. Since the press have already picked up on it, it would be silly for me not to mention my own research. However, please don’t ask me for a copy of the paper, I don’t have the final version yet and there are things being added to the proofs. My hand is therefore rather forced by others.
Finally a huge thank you to Brett Booth of the Carnosauria blog for producing the images above at short notice and in colour too. The artwork is Brett’s and should not be used without his permission.