Pack hunting dinosaurs

[Seijun]

I just want to point out that in my opinion, the kea birds didnt appear to be "pack hunting" at all. I saw a social bird taking advantage of a food source at the same time as the others of its species, but with each bird working only for itself, and without any of the other birds directly benefiting from it.

I might be alone, but I also consider there to be a difference between a true pack hunting species, and a species which will occasionally engage in pack hunting behavior. I personally define a true pack hunting species as having these traits:
- The species will cooperate with others of its own species in order to subdue prey that the entire "pack" can then eat (i.e, the combined efforts of the entire group directly benefit the entire group).
- The above method is one of this species primary means of acquiring food.
- By hunting alone, this species would have a more difficult (if not impossible) time subduing the same prey items that it could have subdued if it hunted in a group. (EDIT: ok, not sure if this last one is really a trait, but it does tend to be true wherever you see pack hunting--of course, if the species didn't need help from a group to take down prey, then there wouldn't be any incentive to hunt in a group in the first place)

I would define pack hunting behavior as being everything stated above, except that the species doesn't necessarily use this method as a primary means of gathering food. So by my definition anyway, I would consider very few species to be true pack hunters, with more only occasionally engaging in pack hunting behavior (and with even more only doing what the keas were doing).

As far as dromies go.. I don't believe there is enough evidence to say whether or not they were pack hunters, whether or not they ever showed pack hunting behavior, or whether they simply fed together on occasion. I would not rule out the possibility that they might have engaged in pack hunting behavior, but I am very skeptical of the idea that they might have been a true pack hunting species. Like others have said, I think that particular theory is fueled more by what we want to think, rather than by what the fossil evidence actually shows.

[Gwangi]

I just want to point out that in my opinion, the kea birds didnt appear to be "pack hunting" at all. I saw a social bird taking advantage of a food source at the same time as the others of its species, but with each bird working only for itself, and without any of the other birds directly benefiting from it.

I might be alone, but I also consider there to be a difference between a true pack hunting species, and a species which will occasionally engage in pack hunting behavior. I personally define a true pack hunting species as having these traits:
- The species will cooperate with others of its own species in order to subdue prey that the entire "pack" can then eat (i.e, the combined efforts of the entire group directly benefit the entire group).
- The above method as one of this species primary means of acquiring food.
- By hunting alone, this species would have a more difficult (if not impossible) time subduing the same prey items that it could have subdued if it hunted in a group.

I would define pack hunting behavior as being everything stated above, except that the species doesn't necasarily use this method as a primary means of gathering food. So by my definition anyway, I would consider very few species to be true pack hunters, with more only occasionally engaging in pack hunting behavior.

As far as dromies go.. I don't believe there is enough evidence to say whether or not they were pack hunters, whether or not they ever showed pack hunting behavior, or whether they simply fed together on occasion. I would not rule out the possibility that they might have engaged in pack hunting behavior, but I am very skeptical of the idea that they might have been a true pack hunting species. Like others have said, I think that particular theory is fueled more by what we want to think, rather than by what the fossil evidence actually shows.

All of this was like a breath of fresh air, thank you! I guess the important part of this discussion is to first define what pack hunting is and you've done that. I only said "wolf like" but if someone does not know what wolves are like that is a meaningless statement on my part.  I agree, what the kea were doing was no different from what piranhas do, just going after the same food source. It is the same thing vultures and crocodiles do. Social animals feeding together.

EDIT: BTW Thagirion, that is a great illustration. See...I do have a sense of humor. Though my name is Gwangi I must point out that I'm an Irritator though.

[Thagirion]

Well thanks Gwangi. I'm gald you liked my drawing.  I was just going by your name and avatar (that is Gwangi isn't it?).

[Gwangi]

Well thanks Gwangi. I'm gald you liked my drawing.  I was just going by your name and avatar (that is Gwangi isn't it?).

It certainly is. 

[Brontozaurus]

If there was pack hunting in dinosaurs, I doubt it would be identical to mammalian pack hunting. This is partly because of the differences in the size of their brains (more specifically the differences in the sizes of particular parts of their brains), but also because dinosaurs and mammals aren't that closely related, so mammalian behaviour isn't a very good analogue. Birds would probably be a better analogue for dinosaur behaviour given that they're the closest living relatives of the dinosaurs in question.

A paper I read posited that dinosaur 'pack hunting' more closely resembled the behaviour of komodo dragons, which do not hunt in packs but will form loose groups around kills, competing with each other for food. There's plenty of evidence for theropods attacking each other, e.g. the bite marks on theropod skulls that could only have been made by other theropods, and a find of a Deinonychus claw embedded in the tail of another Deinonychus. So it's possible that this happened. There's also evidence for at least some form of social behaviour in theropods (and dromaeosaurs in particular) in the form of trackways that show at least two individuals moving together.

So there may have been group hunting behaviour in dinosaurs, but it probably wouldn't have been identical to mammalian pack hunting. They might have grouped around kills, and they might have lived together in very small groups, but true pack hunting is unlikely.

[Metallisuchus]

Tracks are misleading. Who's to say the 2nd Deinonychus tracks weren't made a week after the first?

When I refer to pack-hunting, I'm merely speaking of predators taking advantage of the fact that more predators = a better chance of a kill, whether the intent is to provide food for the other predators or for more selfish reasons. As long as there is that realization that they've got a better shot at taking down more dangerous prey...

Do I think Deinonychus realized that? Yes. Do I think they took advantage of it? Yes. Do I think that they did it for the benefit of the other Deinonychus'? Not necessarily. They may have cooperated, then fought to the death over the carcass, which I guess some of you wouldn't define as true pack hunting. They may have only hunted cooperatively for pure selfish reasons.

So to sum it up, I think they worked together, then there was probably chaotic feeding, with nipping and snarling. This is reminiscent of what you see when various birds gather to eat bread. You don't see extreme violence in most cases, but shows of dominance, and a race to eat the best piece of food.

[Sharptooth]

Bear in mind, guys, that the old "brain size relative to body size" equation is basically an old scientific myth that ethologists are beginning to leave behind; it's not that if you have a bigger brain you're also more intelligent (a VERY relative term, depending on what you mean by "intelligence")... Obviously i'm not saying that non-avian dinosaurs were ALL super-smart or had highly complex cultures, just like modern animals are not all the same; plus, i'd be careful to generalize a behavior; every species has its general set of behaviors, both written inside their DNA and learned, granted, but there's also to take into consideration the fact that EVERY animal, humans included of course, is an individual and not a mass-produced biological machine with no free will... So in a certain group of animals (wolves, cats, eagles, crocs, etc.) there will be a panoply of differents minds, from the smarter to the dumb.

Maybe there was a pack of Deinonychus that pack-hunted while, in another part of Montana there was another group that was happy with just catching smaller preys and didn't engage in such a risky businnes, who knows?
Today there are lions which hunt alone and at least one tribe (if i remember well, in South Africa, there was also a documentary about it if i'm not mistaken) that cooperate to bring down friggin' elephants!
What i want to say is that animal beahvior is way more complicated that many people (including paleontologists) are led to believe and we're just scratching the very tip of this treasure mountain. 

[Metallisuchus]

Very well put, Sharptooth.

Though I think there is validity in brain size. I have heard that bigger brains do not necessarily make an animal more intelligent, but rather leaves them the capacity to be more intelligence.

It's like wattage - I can have a 200-watt amp and a 100-watt amp - and that's the brain size, but the VOLUME is the intelligence.

[Gwangi]

The brain was already covered. Different parts of the brain do different things. Intelligent mammals do the things they do because of their large cerebrums, dinosaurs did not have large cerebrums. Tyrannosaurus had a larger brain than us and a larger brain to body ratio than the average dinosaur but the cerebrum was not so large and the creature was no doubt mostly controlled by instinct. There is nothing insulting about saying an animal is mostly controlled by instinct. I am amazed that anything can be born knowing what it needs to know to survive but pack hunting as defined by Seijun in not an instinctual behavior.

[Seijun]

Well, my definition is hardly official, and it doesn't necessarily have to be a learned behavior.. Some ants do show pack hunting behavior by my definition. A single ant could not possibly hope to kill a fawn, but a few million ants certainly could, and they would all benefit from it. There efforts are also cooperative in the sense that they are all working together (even though they aren't smart enough to comprehend it, and even though their attack is uncoordinated). But I just don't see how there is any way we could possibly know whether or not deinonychus ever hunted in a pack (even uncoordinated, ant-style pack hunting) or whether they only had a habit of congregating to scavenge dead/dying tenontosaurs.

[Sharptooth]

Of course there's nothing wrong to say an animal is "controlled", as you say, by instincts, as long as you also recognize that the same animal has feelings and self-consciousness... Believing that only humans possess these features, relegating other animals as mere organic machines (as Cartesio and mechanicists would have said) is just bad science.

[Gwangi]

Of course there's nothing wrong to say an animal is "controlled", as you say, by instincts, as long as you also recognize that the same animal has feelings and self-consciousness... Believing that only humans possess these features, relegating other animals as mere organic machines (as Cartesio and mechanicists would have said) is just bad science.

Humans are animals too so I certainly don't believe our feelings and self consciousness are unique only to us. You might as well put that one to bed because I don't think anyone on this forum sees the world like that...though I could be mistaken.
Now as for ants, they certainly didn't occur to me but they are so far removed from the types of animals we're discussing that I wouldn't think them all that relevant. They operate on a level that I can't quite grasp. I'm fairly ignorant where invertebrates are concerned. And I know your definition is not official but it seemed to work for the time being.

EDIT: I see people saying we can never know if dromaeosaurs were pack hunters or not but I think it is something we may eventually know for certain. After all, we know what color some dinosaurs were and most of us never saw that coming. Maybe some day we will find the remains of a Tenotosaurus or other herbivore with healed woulds from multiple animals? Or perhaps we'll find another set of fighting dinosaurs but with a trio instead of a one-on-one encounter. You never know, we've learned some remarkable things from fossils.

[Seijun]

My example with ants was an example only of a species that "pack hunts" simply by overwhelming the prey in sheer numbers (unlike a wolf or lion).

[Metallisuchus]

Gwangi, even if we found a Tenontosaurus with multiple wounds that have healed, it would do nothing to support pack hunting theories because we still wouldn't know if those wounds were inflicted by the same predator or multiple predators, or if they were inflicted during the same attack.

I would like to know more about the infamous Tenontosaurus/Deinonychus find though, to see how well it supports what I believe about pack hunting.

[Gwangi]

Gwangi, even if we found a Tenontosaurus with multiple wounds that have healed, it would do nothing to support pack hunting theories because we still wouldn't know if those wounds were inflicted by the same predator or multiple predators, or if they were inflicted during the same attack.

I would like to know more about the infamous Tenontosaurus/Deinonychus find though, to see how well it supports what I believe about pack hunting.

That occurred to me as well but perhaps the healed woulds would show differences between the attacking animals, such as a size difference perhaps. I don't know, I'm only speculating. All I'm saying is that a very convincing fossil may be out there waiting to be discovered.

As for the Tenonotosaurus/Deinonychus there is a good write up about it on the wikipedia entry for Deinonychus. Reading the following is one of the things that got me thinking about the notion of pack hunting dinosaurs. I too used to think without question that dromaeosaurs hunted in packs.

A 2007 study by Roach and Brinkman has called into question the cooperative pack hunting behavior of Deinonychus, based on what is known of modern carnivore hunting and the taphonomy of tenontosaur sites. Modern archosaurs (birds and crocodiles) and komodo dragons display little cooperative hunting; instead, they are usually either solitary hunters, or are drawn to previously killed carcasses, where much conflict occurs between individuals of the same species. For example, in situations where groups of komodo dragons are eating together, the largest individuals eat first and will attack smaller komodos that attempt to feed; if the smaller animal is killed, it is cannibalized. When this information is applied to the tenontosaur sites, it appears that what is found is consistent with Deinonychus having a komodo- or crocodile-like feeding strategy. Deinonychus skeletal remains found at these sites are from subadults, with missing parts consistent with having been eaten by other Deinonychus.[40] On the other hand, a paper by Li et al. describes track sites with similar foot spacing and parallel trackways, implying gregarious packing behavior instead of uncoordinated feeding behavior.[41]

Here is the actual paper A Reevaluation of Cooperative Pack Hunting and Gregariousness in Deinonychus antirrhopus and Other Nonavian Theropod Dinosaurs

[Arioch]

Not even in the "super smart" wolves the hunting strategy is that coordinate; according to recent studies they actually behave more like a mob. There´s no communication between pack members or a ruthless alpha male leading the attack, the thing is way more random than previously thought.

So if a flock (not pack, that´s a mammal term) of certain dromaeosaur species ever engaged in some kind of social hunting it couldn´t possibly be more sophisticated than that or the mob behaviour of crocs.

[Metallisuchus]

I suppose the important issue is how you define pack-hunting. My definition is a lot looser, and has less to do with sharing and coordinated attack patterns. Those are separate, but related topics to me. I know JP's Dromies are exaggerated for the purpose of entertainment, etc. but I don't think we can make every assumption based on crocodiles and birds either.

[Arioch]

Why not ? they´re the closest relatives, and the best we have of such comparison. Most of any animals behaviour is determined by the genes.

Pack hunting is any kind of social hunting, regardless of the complexity. The technical definition is as loose as it gets.

[Sharptooth]

Not even in the "super smart" wolves the hunting strategy is that coordinate; according to recent studies they actually behave more like a mob. There´s no communication between pack members or a ruthless alpha male leading the attack, the thing is way more random than previously thought.

I read that study some time ago and, frankly, it's not that great... Many ethologists which have observed wolves in their habitat for years can confirm that they are well coordinated pack hunters; of course there will be packs who work better than others (remember we i talked about individual variation?) but this doesn't undermines the fact wolves pack hunt, communicate and all the other stuff that study seems to deny 

You say that most of any animal behaviour is determined by the genes? Mmh, it could be, but i'm not that convinced... Learning from experiences, moral codes, cultural differences between groups of the same species, these are big parts of many animals' lives, so i don't think it's always safe to say that a behavior a modern archosaur have could have been also present in a mesozoic one.

X Gwangi:

i wasn't referring to anyone on this forum 
My rant was directed at those academic scientists who have denied these features in animals for years.
About the ants, yeah, i guess they are something different from the animals we're discussing, or maybe i'm wrong, who knows?

[Arioch]

Learning from experiences, moral codes, cultural differences between groups of the same species, these are big parts of many animals' lives,

Is this serious? sorry, can´t tell.