The DinoBase Public Forum

That's just it. Many birds show a some level of social life, and a very high level of intelligence. Since you can't read the whole paper unless you pay $50, I only had the chance to read the abstract, but it makes me wonder just what species of diapsids the authors used.

Ok, so I've gotten a hold of the paper and had a read through it. It's pretty compelling, more so than I'd initially thought from the abstract. The authors are casting doubt over Deinonychus regularly hunting large prey in a highly coordinated pack-hunting style, mainly based on the loose cooperative hunting styles seen in extant archosaurs (a couple of species of crocodiles and plenty of examples of predatory birds) and the komodo dragon.

Komodo dragons are known to solitarily take down prey as much as 10 times its own size. On this basis, the authors mention that it would be possible for a 70 - 100 kg Deinonychus to solitarily take down a Tenontosaurus anywhere between 700 - 1000 kg.

The fossil sites are reexamined as well. The Deinonychus skeleton(s) found with the Tenontosaurus may have been victim to intraspecific fighting and were killed and eaten by larger adult Deinonychus as frequently observed in komodo dragons and some predatory birds. The large degree of disarticulation of the Deinonychus skeleton as opposed to the more articulated Tenontosaurus seem to indicate that the freshly killed Deinonychus may have been more apetising for the aggregated Deinonychus individuals. The other individuals probably aggressively tore apart and consumed the dead Deinonychus, leaving only the bony bits with not much meat like the manus, pes and tail.

Although, you'd still have to be cautious of this theory as well. Just because it sounds compelling doesn't mean it's a proven fact, it's only yet another competing hypothesis. You'd have to be extra critical of such a critical paper as well. It challenges a historical concept in a very critical way and so deserves a critical review.

So my default position is to be sceptic.

Komodos seem like a poor comparison--predatory birds would be more apt, and predatory birds favor a solitary or paired existence.

I havew also gotten a hold of the paper and I have to say I actually found it pretty unconvincing. Their arguments against the Deino / Tenonto associations representing pack hunting are OK, but they then make the same error that accuse previous researchs of doing, building a whole argement based on one theme.

Theirs is that since this association in not evidence for pack hunting and that diapsids do not hunt in groups, just loose assocaitions, then clearly dinosaurs didn't. However, this is flawed for two reasons.

The first is that disproving one unique site as being a pack hunting assocaition does not rule out pack hunting - merely that this one incident is not evidence for it. As I say above and elsewhere, this is not the kind of thing you ever expect to be preserved (whole prides of lions do not die together in one place as a rule!) so absence of evidence is not evidence of absence. Secondly they go a long way to explain how all 'group' hunting behaviour in birds are just associations and not pack hunting efforts. Thus they conclude there is no EPB inference to pack hunting with neither birds nor modern reptiles showing the behaviour.

However they fail to mention the two examples I gave above - caracars and hornbills which do manifestly hunt in groups (or pairs) as social hunters and these were the first things I thought of without any research, I am sure there are others. In short, their 'evidence' for a lack of pack hunting is that this one association doesn't count (which it might, I can give a few ideas as to how the assication might still be valid), and that birds are not pack hunters (when some of them are). It's hardly the best explanation of the data!

The problem I see here is that the evidence for pack-hunting is also not convincing...it's just been a long held opinion by the majority without any rigorous hypothesis testing - in that respect, I like this paper.

It's quite similar to the recent study on dinosaur digestions (http://dinobase.gly.bris.ac.uk/forum/vi … php?id=567) - it tests the nutritional values of possible sauropod fodder - gymnosperms; something that has been long regarded to be poor in nutritional value but with no experiments or observations to back this notion up.

David Hone wrote:

There is a reason modern birds do not hunt large pery in packs, and that is big mammals out competing them, not becuase they lack the ability/intelligence or inheritence to do so. They are not dominant predators, so it is highly unlikley they would be pack hunting big prey.

Yes, I agree. Dinosaurs were the dominant terrestrial megafauna of the Mesozoic so I would imagine similar selective pressures acting on them that are acting on modern mammalian megafauna, one of which is the possibility of coordinated hunting strategies. I don't believe that phylogeny has that much control over behavioral adaptations when it comes to niche occupation. Adaptive radiation has continuously shown amazing stuff throughout the whole history of life.

Having said that, I think Roach and Brinkman's (2007) approach is a conservative safe bet given the information available in modern archosaurs...at least in their review anyway - Dave, I know you say otherwise and I'm in no position to challenge you on that because I'm no ethologist. I guess this is a possible "comment on" type paper that someone can do?