Tyrannosaurus - pack hunter?

Kess73

Dino gangs is having it's premiere on Discovery.

Basically is about Dr. Phil Currie's theory, based on the finding of 68 T-Rex remains in close proximity, that T-Rex was a pack hunter with Juveniles and adults hunting as part of one pack but with different roles in the hunt.

If anyone has two hours to spare it could be an interesting watch.

Kess73

http://http://www.newscientist.com/blogs/culturelab/2011/06/did-dinosaurs-hunt-in-packs.html


A few weeks ago, two UK palaeontologists announced the discovery of the world's tiniest dinosaur. The diminutive species was just 33 to 44 centimetres in length and weighed around 200 grams - all of which the pair worked out from a single vertebra. It's just one example of how a skilful palaeontologist can see the big picture - or in this case the little picture - from what most of us would view as the scrappiest of data.

Philip Currie at the University of Alberta in Edmonton, Canada, knows all about squeezing information out of relatively unpromising starting material. He has spent the last 15 years chipping away at an impressively bold hypothesis: that the tyrannosaurs hunted in packs rather than alone, making them even more formidable than we had thought. The hypothesis gets a thorough examination in Dino Gangs, a 2-hour documentary that airs on the Discovery Channel in the UK this Sunday. (Currie also co-wrote an accompanying book by the same name.)

This is controversial stuff, but happily the documentary makers give the sceptics a voice - several leading palaeontologists explain exactly why Currie's idea has yet to convince many in the community. Fundamentally, they say, working out anything meaningful about how a long-dead animal behaved 70 million years ago is always going to be tricky.

But Currie isn't daunted. Early on we're told that the most convincing supporting evidence would come in the form of a tyrannosaur mass grave - shattering the consensus view of the beasts as solitary animals. And Currie comes up trumps: not only does he find 23 tyrannosaurs buried together in Canada, but he also explores a site in the Gobi desert where no less than 68 tyrannosaurs have been found within spitting distance of one another.

But then the wheels begin to come off. A geological analysis of the Gobi site suggests the skeletons there were deposited over hundreds of thousands of years - that their geographical proximity is just a quirk of prehistory. And things get worse: a sceptical palaeontologist tells us that even finding multiple tyrannosaurs buried together isn't enough. The dino gang hypothesis rests on evidence of multiple tyrannosaurs at a kill site - something yet to be found.

Fieldwork in the Gobi desert, Mongolia (Image: Discovery Channel)

Undeterred, Currie turns to modern predators in his quest for convincing evidence, and in the process we visit such exotic locations as Indonesia (for its Komodo dragons), South Africa (for its lions)... and England, home not to giant predators but to an impressive motion capture studio which helps establish that young tyrannosaurs were twice as swift as the bulky adults. Did the two team up to hunt as lions do?

What's clear is that Currie - and the documentary makers - have given serious thought to the dino gang hypothesis. If slick, big-budget presentation was enough to persuade, we'd have a winning theory 90 minutes into the show. But it's not, and the sceptics remain unmoved.

Currie's final throw of the dice is X-ray scans of a tyrannosaur skull, which show its brain was six times bigger than any other dinosaurs alive at the time. Is this the clincher? "I wish we could point to a cooperative hunting lobe of the brain - sadly it doesn't really work that way," says Larry Witmer at Ohio University in Athens, who helped Currie perform the scans. Currie and Witmer do, at least, decide that there's nothing in the tyrannosaur brain to suggest it was incapable of cooperation. Needless to say, others disagree.

But we've no time for a riposte from Currie, although we are treated to a curious epilogue that suggests a better understanding of dinosaur behaviour could prove informative for understanding our own destructive ecological behaviour.

The impressive, if speculative, evidence Currie has already amassed is presented in an easy to follow form in Dino Gangs, complemented with the obligatory Jurassic Park-like CGI animations. But the lasting impression is of a jigsaw with its final, vital piece missing. The great thing about science, though, is that it doesn't end when the credits roll. That final piece is always just a fossil away. And while we wait for Currie to find it, there are certainly worse ways to kill 2 hours.

Dino Gangs premiers on the Discovery Channel in the UK at 9pm Sunday 26 June

Kess73

https://www.youtube.com/watch?v=kq98vitA4I0

The one thing that kept going through my head when I saw the trailer was that the bodies could have built up near a swamp/marsh type area where predators where drawn in by the smell of carrion, only to get stuck in the swamp and then in turn become the remains whose scent draws in more predators.

But if the spot with the T Rex skeletons turns out not to have the remains of other species there then it could become more interesting.


The other ideas that kicked around in my head when I saw the trailer was something like an elephant graveyard, but then that would support the pack or group theory.

Guess I will have to wait until tonight to watch the show and then base my own take upon what I see.

Galvasean

Dinosaur Tracking Blog absolutely tore Phil Currie a new one over this:
http://blogs.smithsonianmag.com/dinosaur/2011/05/tarbosaurus-gangs-what-do-we-know/

I admire Phil Currie a lot (he's one of my favourite palaeontologists), but in this case I think he's taking a bit of a flight of fancy. He strikes me as someone who really wants the idea of pack hunting tyrannosaurs to be true.

Kess73

Going by some of the reviews I have read for the show, at least those that disagree get a say on the same show as well, unlike when Hack Horner comes out with one of his theories.


If nothing else, the show is an excuse to get the old grey matter ticking over.

Galvasean

Indeed. I'm hoping for a good clean fight. Nothing worse than a documentary that pretends the opposition opinions don't exist (eg: Valley of the T-rex).

Galvasean

Not bad so far. Can't say I like the way they use stock footage of aucasaurs and carcharodontosaurs and try pass them off as tyrannosaurs though...

Galvasean

Triceratops standing in for Protoceratops :mad:

Adam Khor

Galvasean wrote: »

Not bad so far. Can't say I like the way they use stock footage of aucasaurs and carcharodontosaurs and try pass them off as tyrannosaurs though...

Galvasean wrote: »

Triceratops standing in for Protoceratops :mad:

Sounds like its gonna be yet another BAAAD dino documentary.

Galvasean

Adam Khor wrote: »

Sounds like its gonna be yet another BAAAD dino documentary.

I found it a little spoon feedy. Granted not everyone uses our lovely forum and is as clued in all things prehistoric as we are. I found I knew everything stated in it already. It dragged somewhat. Certainly didn't need to take up a two hour slot. That said, I'm sure people with less dino knowledge would find it illuminating.
The documentary had no real conclusion either. The main question posed was if Tyrannosaurus hunted in packs. The answer was a resounding 'maybe'.

Adam Khor

Galvasean wrote: »

I found it a little spoon feedy. Granted not everyone uses our lovely forum and is as clued in all things prehistoric as we are. I found I knew everything stated in it already. It dragged somewhat. Certainly didn't need to take up a two hour slot. That said, I'm sure people with less dino knowledge would find it illuminating.
The documentary had no real conclusion either. The main question posed was if Tyrannosaurus hunted in packs. The answer was a resounding 'maybe'.

As is the case with most dinosaur documentaries, and ALL History Channel documentaries.

Kess73

Got the impression that it was aimed at a younger audience. Nothing new in what was said, and calling dinos by their wrong names got annoying.


The same show could have been done in 45mins and been a far better watch.

Galvasean

The book is on sale in Eason. I'd be interested to see if the book has more to it than the doc. Not for €26.40 though.

Alvin T. Grey

Tyrannosaurus rex.

Loner or leader of the pack?

Discuss with reasoned arguement please.

dlofnep

Loner in the sense that it did not hunt in packs - but probably hunted with it's children, and possibly it's mate. Children had longer proportioned legs and were lighter build, which suggested they ran quicker and for longer periods.. They probably ushered the prey towards Mommasaurus Rex who got the kill.

I think the T-Rex would have been far too territorial to hunt in packs. And I think there was sufficient slow prey and defenceless prey, which would not really require pack hunting.

Galvasean

12 bucks on Amazon. What the hell do Eason think they're playing at? :rolleyes:
http://www.amazon.co.uk/Dino-Gangs-Curries-Science-Dinosaurs/dp/0007413394/ref=sr_1_1?s=books&ie=UTF8&qid=1315320992&sr=1-1

Alvin T. Grey

dlofnep wrote: »

Loner in the sense that it did not hunt in packs - but probably hunted with it's children, and possibly it's mate. Children had longer proportioned legs and were lighter build, which suggested they ran quicker and for longer periods.. They probably ushered the prey towards Mommasaurus Rex who got the kill.

AKA Little Das...

I think the T-Rex would have been far too territorial to hunt in packs. And I think there was sufficient slow prey and defenceless prey, which would not really require pack hunting.

For hadrosaurs, maybe. But I disagree with that as far as ceretopsians are concerned and we know that they preyed on both.

A ceretopsian had too many sharp pointy bits to defend itself with, my guess is that it could have kept a large theropod at bay with those. The way to take it would have been to out flank it and attack from behiend the frill. Such an act would be easiest achieved by focusing its attention on one animal leaving the other(s) to bring it down.
Which suggests a pack behivour.

Galvasean

Hadrosaurs were by no means defenseless. They were incredibly fast!
Cool as the idea is I'm not convinced by the T rex pack idea. There just isn't any substantial evidence going for it.

ps: Plan to merge with 'Dino Gangs' thread, any objections?

Adam Khor

dlofnep wrote: »

I think the T-Rex would have been far too territorial to hunt in packs. And I think there was sufficient slow prey and defenceless prey, which would not really require pack hunting.

Hadrosaurs were not defenseless. They weren´t slow (they were recently confirmed to have been fast runners, which is the only thing that makes sense considering who was chasing after them), and they had heavy, powerful tails that could be used to hit predators. According to some paleontologists I talked too, the edges of hadrosaur's beaks weren´t as nice and soft as they look in most reconstructions; they had keratinous edges that were very sharp and sometimes even serrated, meaning they probably could bite if necessary. I'm not saying they were equiped to fight with a T-Rex the way a Triceratops would, but they weren´t all helpless either.

As for the pack-hunting theory, I can see it work for other smaller carnivorous dinosaurs, but not T-Rex. It was way too big, and unlike carcharodontosaurs which seem to have been specialized sauropod hunters, T-Rex was feeding on prey its own size or smaller.

Even an adult Edmontosaurus or Triceratops wouldn´t be large enough for a whole pack of hungry Tyrannosaurus. The bigger, stronger ones would probably eat most of the kill and leave the smaller weaker members hungry. If we consider that the smaller members of the pack would probably be the ones chasing prey at high speed (as they would be faster than their biggest pack mates), it would be a tremendous energy waste.

Sure, some modern day predators like lions hunt in packs, and yes, the biggest ones (the males) monopolize the kill until they're full, but, let's consider that lions often prey on animals much bigger than themselves. Even if sometimes the lionesses and cubs go hungry, there's always the possibility of taking down a Cape Buffalo, or a zebra and have a satisfying meal for everyone.

The only animal I can think of big enough to feed a pack of several adult T-Rex would be an Alamosaurus, but a) it seems to have been rare, b) it was way too big to be targeted often, c) there's plenty of evidence that T-Rex preyed mostly on hadrosaurs and ceratopsians, and d) Alamosaurus seemingly wasn´t very widespread.

It just makes a lot more sense, to me anyways, if T-Rex was a lone hunter, or at most, if it hunted in pairs, like some birds of prey do today.

Kess73

Adam Khor wrote: »

Hadrosaurs were not defenseless. They weren´t slow (they were recently confirmed to have been fast runners, which is the only thing that makes sense considering who was chasing after them), and they had heavy, powerful tails that could be used to hit predators. According to some paleontologists I talked too, the edges of hadrosaur's beaks weren´t as nice and soft as they look in most reconstructions; they had keratinous edges that were very sharp and sometimes even serrated, meaning they probably could bite if necessary. I'm not saying they were equiped to fight with a T-Rex the way a Triceratops would, but they weren´t all helpless either.

As for the pack-hunting theory, I can see it work for other smaller carnivorous dinosaurs, but not T-Rex. It was way too big, and unlike carcharodontosaurs which seem to have been specialized sauropod hunters, T-Rex was feeding on prey its own size or smaller.

Even an adult Edmontosaurus or Triceratops wouldn´t be large enough for a whole pack of hungry Tyrannosaurus. The bigger, stronger ones would probably eat most of the kill and leave the smaller weaker members hungry. If we consider that the smaller members of the pack would probably be the ones chasing prey at high speed (as they would be faster than their biggest pack mates), it would be a tremendous energy waste.

Sure, some modern day predators like lions hunt in packs, and yes, the biggest ones (the males) monopolize the kill until they're full, but, let's consider that lions often prey on animals much bigger than themselves. Even if sometimes the lionesses and cubs go hungry, there's always the possibility of taking down a Cape Buffalo, or a zebra and have a satisfying meal for everyone.

The only animal I can think of big enough to feed a pack of several adult T-Rex would be an Alamosaurus, but a) it seems to have been rare, b) it was way too big to be targeted often, c) there's plenty of evidence that T-Rex preyed mostly on hadrosaurs and ceratopsians, and d) Alamosaurus seemingly wasn´t very widespread.

It just makes a lot more sense, to me anyways, if T-Rex was a lone hunter, or at most, if it hunted in pairs, like some birds of prey do today.

Would lean towards the bird of prey comparison as well.

My own take is that the adults would have hunted seperately for a fair chunk of the time, but possibly hunted as a pair or as a loose pair during the breeding season and after the Rex younglings "fledged".

I spend a lot of time observing birds of prey, especially sparrowhawks as I have been lucky enough to have had a regular female who has nested on my land for a few years now, and when the young fledge it is not unusual to see the young travelling together or to see them following the male and watching/learning.

I have also observed on a number of occasions the two adults working in manner that would suggest cooperation, but only during the breeding season.

T Rex doing something similar makes a lot of sense to me, with the young probably staying with the female until they are capable of catching and killing prey in their size bracket.



I have a theory that modern raptors offer the best clue as to how theropods hunted with the majority of raptors being lone hunters outside of the breeding season or at most , but the fly in the ointment would be the Harris Hawk. A medium sized raptor that can hunt very well alone but also pack hunts when there is a need to take down larger prey. Interestingly enough the Harris Hawk, when pack hunting, shares food quite well as a group with anything from 2 to 8 birds taking part in such activities. For my money the Harris hawk's behaviour is probably quite similar to the behaviour of the various dromaeosaurids, something that most would believe anyway, but the sparrowhawk behaviour is my best bet as to how the medium to large sized theropods interacted. I am using sparrowhawks as an example because as well as them being a very adaptable predator that will and can change it's ambush strategies within minutes of an obstruction presenting itself, they are a species that we here in Ireland can view on a regular basis in the countryside and in sub urband/Urban areas all over the country.

Adam Khor

Kess73 wrote: »

Would lean towards the bird of prey comparison as well.

My own take is that the adults would have hunted seperately for a fair chunk of the time, but possibly hunted as a pair or as a loose pair during the breeding season and after the Rex younglings "fledged".

I spend a lot of time observing birds of prey, especially sparrowhawks as I have been lucky enough to have had a regular female who has nested on my land for a few years now, and when the young fledge it is not unusual to see the young travelling together or to see them following the male and watching/learning.

I have also observed on a number of occasions the two adults working in manner that would suggest cooperation, but only during the breeding season.

T Rex doing something similar makes a lot of sense to me, with the young probably staying with the female until they are capable of catching and killing prey in their size bracket.



I have a theory that modern raptors offer the best clue as to how theropods hunted with the majority of raptors being lone hunters outside of the breeding season or at most , but the fly in the ointment would be the Harris Hawk. A medium sized raptor that can hunt very well alone but also pack hunts when there is a need to take down larger prey. Interestingly enough the Harris Hawk, when pack hunting, shares food quite well as a group with anything from 2 to 8 birds taking part in such activities. For my money the Harris hawk's behaviour is probably quite similar to the behaviour of the various dromaeosaurids, something that most would believe anyway, but the sparrowhawk behaviour is my best bet as to how the medium to large sized theropods interacted. I am using sparrowhawks as an example because as well as them being a very adaptable predator that will and can change it's ambush strategies within minutes of an obstruction presenting itself, they are a species that we here in Ireland can view on a regular basis in the countryside and in sub urband/Urban areas all over the country.

I know the Harris Hawk very well; I've seen it and photographed it in the wild.

Kess73

Adam Khor wrote: »

I know the Harris Hawk very well; I've seen it and photographed it in the wild.

Lovely bird isn't it?

Which sub species did you photograph? Seen them in the wild in North America and have handled falconry Harris Hawks over here and in the UK.

Adam Khor

Kess73 wrote: »

Lovely bird isn't it?

Which sub species did you photograph? Seen them in the wild in North America and have handled falconry Harris Hawks over here and in the UK.

P. u. harrisi :>

Kess73

Adam Khor wrote: »

P. u. harrisi :>

Where were you observing them? Mexico?

Adam Khor

Kess73 wrote: »

Where were you observing them? Mexico?

Yeah, western Mexico, a dry lakebed. There's tons of raptors hunting in that area, including red-tailed hawks, white-tailed hawk, crested caracara, American kestrel and even the occasional kite.
Also, plenty of roadrunners

Galvasean

Galvasean wrote: »

ps: Plan to merge with 'Dino Gangs' thread, any objections?

Threads now merged. Carry on

Alvin T. Grey

I have a few theories, mostly based around clutch numbers, growth rates, morphology that I'm putting together. Things have been a bit hectic here for the last couple of weeks, so please bear with me.

Adam Khor

Alvin T. Grey wrote: »

I have a few theories, mostly based around clutch numbers, growth rates, morphology that I'm putting together. Things have been a bit hectic here for the last couple of weeks, so please bear with me.

Do we even have T-Rex nests or eggs? I don´t think so... I remember watching a documentary ages ago about a possible tyrannosaur nest found in Asia, I believe? But never heard about it again...

Kess73

Adam Khor wrote: »

Do we even have T-Rex nests or eggs? I don´t think so... I remember watching a documentary ages ago about a possible tyrannosaur nest found in Asia, I believe? But never heard about it again...

Pretty sure that no confirmed nests and certainly no confirmed eggs have ever been found. Any guesstimations on T-Rex clutch numbers etc would have to be based on what is known of other theropods.

Adam Khor

Kess73 wrote: »

Pretty sure that no confirmed nests and certainly no confirmed eggs have ever been found. Any guesstimations on T-Rex clutch numbers etc would have to be based on what is known of other theropods.

Not good enough... clutch size can vary a lot even among related species today. Philippine, Slender-Snouted and Freshie crocodiles lay very few eggs whereas Nile, Saltie and Black Caiman can lay up to 60-90 eggs per clutch!

Does anyone has data on clutch sizes of other dinosaurs? They would always be a better comparison than crocodilians, and although I remember reading about this I honestly can´t remember the numbers anymore :S

Kess73

Adam Khor wrote: »

Not good enough... clutch size can vary a lot even among related species today. Philippine, Slender-Snouted and Freshie crocodiles lay very few eggs whereas Nile, Saltie and Black Caiman can lay up to 60-90 eggs per clutch!

Does anyone has data on clutch sizes of other dinosaurs? They would always be a better comparison than crocodilians, and although I remember reading about this I honestly can´t remember the numbers anymore :S

There is data on nests and clutch sizes of other theropods including one or two of the earlier tyrannosaurids if I am not mistaken, so as I said in the earlier post, that is where any guesstimations on what T-Rex clutches were like will come from imo. Would be pointless to use crocodilians as a comparative species in order to gauge nesting habits and clutch sizes. If I was goung to try and use any modern animals for a loose comparison on that front then I would lean towards modern raptors for a very rough and potentially very tenuous comparison,

Adam Khor

Kess73 wrote: »

There is data on nests and clutch sizes of other theropods including one or two of the earlier tyrannosaurids if I am not mistaken, so as I said in the earlier post, that is where any guesstimations on what T-Rex clutches were like will come from imo. Would be pointless to use crocodilians as a comparative species in order to gauge nesting habits and clutch sizes. If I was goung to try and use any modern animals for a loose comparison on that front then I would lean towards modern raptors for a very rough and potentially very tenuous comparison,

That is why I didn´t mention birds of prey... most of them lay very few eggs, usually two, and all the dinosaur nests I remember reading about had many more eggs...

But, maybe the eggs were not being laid by a single female? Maybe they were like ostriches and several females would lay their eggs in the same nest for the male to take care of? Not necessarily T-Rex's case, though.

GWolf

Well, clutch size could easily be dependent on whether or not Tyrannosaurus DID engage in pack hunting. If they did, small clutches with slow growing infants would be expected. If not, more rapid growth and larger clutches wouldn't shock. Crocodilians have relatively primitive parenting skills, a lot of babies die, so they need big clutches.

Given the pretty solid evidence that Albertosaurus was at least gregarious if not an active pack hunter (given what some birds can show in terms of social behaviour eg Arabian babbler, a coherent pack would work for me, although probably more on the lines of a lion pride than wolves) and the fact there have been young rexes found in proximity to adults, as well as some pathological evidence, would suggest at least some temporary social interaction. Maybe it's just coming together to start the chicks off, or given rexes may have taken 12 years to hit reproducing age, maybe the adults actively reared the young until they were of a size that they could fend for themselve, or on the outside (very outside I'll grant but again, some avian examples exist), juveniles remaining with or close to their parents to establish a fully functional, socially ordered group, but I would not be shocked by a discovery of a mass T. rex death assemblage (relatively mass...4 or 5 individuals mass).

Adam Khor

GWolf wrote: »

I would not be shocked by a discovery of a mass T. rex death assemblage (relatively mass...4 or 5 individuals mass).

I thought something like this had already been found in Montana, I believe?

GWolf

Adam Khor wrote: »

I thought something like this had already been found in Montana, I believe?

Any link?

Adam Khor

GWolf wrote: »

Any link?

No, I saw it in a documentary I believe.

SvenLittkowski

Hmm, interesting theory. Let's wait and see, if this gets confirmed...