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Tyrannosaurus Rex - Hunter or Scavenger?
Topic Started: Jul 15 2012, 10:00 AM (12,435 Views)
DinosaurMichael
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So I just finished watching Valley of the T-Rex and though I accept Jack Horner's opinion about T-Rex being just a scavenger. I still think T-Rex was both a Predator and a Scavenger.



So what do you guys think T-Rex is in your opinion. A Hunter, Scavenger or Both?
Edited by DinosaurMichael, Jul 16 2012, 12:59 AM.
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Ausar
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^And that is exactly what I think Tyrannosaurus was. There is no way any true carnivore can be a pure scavenger.
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theropod
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Only a facultative scavenger, obligate scavengers don't exist among terrestrial vertebrates. There is also plenty of fossil evidence for active (insucessful) attacks on large vertebrates (Triceratops horns & frill, hadrosaur caudals), and more signs of feeding (the infamous triceratops sacrum and pelvis with the deep ghashes) than would be expected from a scavenger (which would typically consume the bones completely since at the time such a big animal arrives, not much else would be left).
Also, supporters of the scavenger hypothesis have failed in an epic manner to bring forth functional evidence for T. rex (or other non-vulture theropods for that matter) being obligate kleptoparasites. Much more, the evidence points towards a comparatively mobile animal with weaponery suited much more for active combat than carcass-dismemberment.

Crocuta crocuta actually hunts more of its food than lions do. It is by no means an example of a scavenger, that's an extremely bad cliché. It is durophagous, and it undoubtedly scavenges frequently, just like most carnivores, but it is, above all, an active hunter. And yes, the spotted hyaena might be a good analogy for t. rex in some points (bulky, massive skull, tremendously strong bite, thick-boned, bulky forequarters & neck).
Edited by theropod, Jul 17 2013, 02:54 AM.
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Taipan
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Bandog
Jul 17 2013, 02:38 AM
They are primarily hunters and scavenge a lot less than is lead on.


Depends on region and circumstance.

Posted Image

As the above from Hans Kruuk's landmark book & study "The Spotted Hyena." there's a great contrast in hunting v scavenging dependent on the circumstance. Where hyena density is high eg. ngorongoro crater (1.7 hyena per km2), - they predate more than they scavenge. In the Serengeti however where hyena density is low,(0.24 hyena per km2) they scavenge more. In some age classes of prey its over 50%

The ratio too affects lion behaviour, because where hyena density is high, lions usurp more hyena 'kills/carcasses scavenged' (84%) and confirmed hyena kills (22%), whereas in areas of low hyena density that rate falls to 18%.

Another fact to consider is how typical the predation/scavenging behaviour of Ngorongoro crater lions is. There are less than 100 of them and they suffer terribly from inbreeding, whereas there are over 2000 Serengeti lions living a more natural existence. I wouldnt generalise typical lion behaviour from a small inbred population of lions.

Therefore I'd say in general Hyenas do scavenge more than lions, in normal circumstances.

Back on to the T-Rex - lion or Hyena , if Horner meant by Hyena - "a creature that fed on creatures large and small, both carrion and fresh-killed prey." (as stated in the article), he is not wrong. Maybe he needs to consider Lion scavenging though for the other side of his coin. He doesnt specify Spotted either - Browns and Stripped are known scavengers too. He could have used Leopard v Hyena. Dinosaur people arent always knowledgeable re modern predators.

If T-Rex - lion or Hyena - meant predatory capability, maybe he's right.
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Bandog
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Taipan
Jul 17 2013, 05:09 PM
Bandog
Jul 17 2013, 02:38 AM
They are primarily hunters and scavenge a lot less than is lead on.


Depends on region and circumstance.

Posted Image

As the above from Hans Kruuk's landmark book & study "The Spotted Hyena." there's a great contrast in hunting v scavenging dependent on the circumstance. Where hyena density is high eg. ngorongoro crater (1.7 hyena per km2), - they predate more than they scavenge. In the Serengeti however where hyena density is low,(0.24 hyena per km2) they scavenge more. In some age classes of prey its over 50%

The ratio too affects lion behaviour, because where hyena density is high, lions usurp more hyena 'kills/carcasses scavenged' (84%) and confirmed hyena kills (22%), whereas in areas of low hyena density that rate falls to 18%.

Another fact to consider is how typical the predation/scavenging behaviour of Ngorongoro crater lions is. There are less than 100 of them and they suffer terribly from inbreeding, whereas there are over 2000 Serengeti lions living a more natural existence. I wouldnt generalise typical lion behaviour from a small inbred population of lions.

Therefore I'd say in general Hyenas do scavenge more than lions, in normal circumstances.

Back on to the T-Rex - lion or Hyena , if Horner meant by Hyena - "a creature that fed on creatures large and small, both carrion and fresh-killed prey." (as stated in the article), he is not wrong. Maybe he needs to consider Lion scavenging though for the other side of his coin. He doesnt specify Spotted either - Browns and Stripped are known scavengers too. He could have used Leopard v Hyena. Dinosaur people arent always knowledgeable re modern predators.

If T-Rex - lion or Hyena - meant predatory capability, maybe he's right.
I was pointing more towards the fact that hyenas do not scavenge as extensively as they are popularly portrayed but point taken. I couldn't think of any large carnivoran that is a dedicated scavenger and because of that, it is unlikely rex was either. I also find it unlikely that tyrannosaurus was even primarily a scavenger.
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Taipan
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Bandog
Jul 17 2013, 05:21 PM
I was pointing more towards the fact that hyenas do not scavenge as extensively as they are popularly portrayed but point taken.


You were right - they are portayed in the way you described. I just thought I'd add a bit more on the lion/hyena scavenging/predation comparison.

As you'd know these kind of beliefs perpetuated in documentaries affect lions too - Male lions are commonly portrayed as lazy lumps that dont hunt but rely on the hard work of lionesses. Reality is male lions are very effective huners of mega-fauna.

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Bandog
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Better than that, they spend time hunting alone when they first get chased off to find their own pride. Lioness' aren't often without a pride.
Edited by Bandog, Jul 17 2013, 05:43 PM.
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theropod
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Either way and overall, spotted hyaenas don't scavenge more than they hunt, and they actually don't scavenge much at all.

And godzillasaurus was refering specifically to the spotted hyaena.

for horners claims, this summarises them:
Quote:
 
Paleontologist Jack Horner of the Museum of the Rockies (Bozeman, MT) has proposed that T.rex could not have been a predator. His arguments against predation include its small eyes (needed to see prey), small arms (needed to hold prey), huge legs (meaning slow speed) and that there is no evidence for predation — bones have been found with tyrannosaur teeth embedded in them or scratched by them, but so far no study has shown that tyrannosaurs killed other dinosaurs for food (a bone showing tyrannosaur tooth marks that had healed would be strong evidence for predation).

His evidence supporting scavenging include its large olfactory lobes (part of the brain used for smell), and that its legs were built for walking long distances (the thigh was about the size of the calf, as in humans). Vultures have large olfactory lobes and are good at soaring to cover long distances.

http://www.ucmp.berkeley.edu/diapsids/saurischia/tyrannosauridae.html

That's also what most people are arguing against, and what has sparked this debate in the first place, so the relevant topic.

And sadly for Horner, he is completely disproven on all these points. T. rex had rather large, forward-facing eyes and reportedly good eyesight. "huge legs" are not indicative of slow speed, but the opposite. "Small arms" are not just found in Tyrannosaurs, but in many other theropods (they are even smaller in abelisaurs), and tend to decrease in size in all large theropods with increasing size, they are certainly beneficial, but obviously not needed for beign a hunter.
At least two healed herbivore bones bitten by T. rex are known.

Extant canids too have excellent sense of smell, and they are also able to walk long distances.
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Godzillasaurus
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Either way and overall, spotted hyaenas don't scavenge more than they hunt, and they actually don't scavenge much at all.


Gee, I didn't know that :$
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Taipan
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Godzillasaurus
Jul 20 2013, 01:14 AM
Quote:
 
Either way and overall, spotted hyaenas don't scavenge more than they hunt, and they actually don't scavenge much at all.


Gee, I didn't know that :$


Well read the info I posted above regarding location and circumstance affecting scavenging rate. Here's a study whivch finds 80% of the carcasses Spotted Hyenas feed upon in kruger NP:

Posted Image
Source : Hyena Nights and Kalahari Days
By Gus Mills, M. G. L. Mill

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Makaveli7
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I think the best comparison is a Hyena. They are efficient at both hunting and scavenging, which T. rex is as well. I imagine it would be a good ambush predator.
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Jinfengopteryx
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Taipan
Jul 17 2013, 05:39 PM
Male lions are commonly portrayed as lazy lumps that dont hunt but rely on the hard work of lionesses. Reality is male lions are very effective huners of mega-fauna.
I know, in the "What animals do you hate" thread, I have posted a link debunking that:
http://carnivoraforum.com/single/?p=8557311&t=9926437
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Taipan
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Jinfengopteryx
Aug 4 2013, 07:45 PM
Taipan
Jul 17 2013, 05:39 PM
Male lions are commonly portrayed as lazy lumps that dont hunt but rely on the hard work of lionesses. Reality is male lions are very effective huners of mega-fauna.
I know, in the "What animals do you hate" thread, I have posted a link debunking that:
http://carnivoraforum.com/single/?p=8557311&t=9926437


Thanks. Good to see you posting again. Holiday?

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Ausar
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So the final conclusion is: T.rex is an opportunistic animal that will scavenge from carcasses and hunt live, dinosaurian megafauna.
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Godzillasaurus
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Aug 4 2013, 08:43 PM
So the final conclusion is: T.rex is an opportunistic animal that will scavenge from carcasses and hunt live, dinosaurian megafauna.
Yes. We are not denying that it was an active hunter, but it probably would have scavenged occasionally.
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Jinfengopteryx
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Taipan
Aug 4 2013, 08:39 PM
Holiday?

Yes!
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