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Re: Bite Marks on Bones |
By Luke Owens on
12/10/2007 10:15 AM |
Can you say "Tempest in a teapot"? I'm sure you can. That's basically what your contention about T. Rex being a scavenger is. To be convincing you have to show two things, either historically or currently: 1) a predator that DOES NOT engage in scavenging behaviour, and 2) a scavenger that NEVER preys on other animals.
I doubt you can, since neither category exists. The whole scavenger vs. predator assignment is moot and always has been. Rather than being based on actual behaviour of the animal, it's based on human perception of observed activity...and we all know what happens to the observed. |
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Re: Bite Marks on Bones |
By jhorner on
12/10/2007 10:19 AM |
Thank you for your tempest comment on the teapot. Actually, in science all that we are required to do is propose hypotheses that are backed up with physical evidence. When it comes to T.rex its bone-crushing teeth, huge olfactory lobes, incapability of running, vestigial arms and commonness in its ecosystem are all characteristics that support scavenging. There is no evidence to support predation. Science is NEVER about negative evidence, so I need not find a predator that "does not" scavenge, but for an animal that is a scavenger that never preys on other animals, check out the Turkey vulture (another theropod dinosaur).
As a scientist I've actually not published on the subject of scavenger vs. predator, but instead use it as a means to illustrate to children how the scientific process works. That no matter how much you want something to be, you have to have physical evidence to back it up, and when it comes to behavioral inference, the animals that you use to make comparisons have to be closely related. Birds are living dinosaurs so they are useful whereas mammals are not.
Thanks again for your comment.
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Re: Bite Marks on Bones |
By Luke Owens on
12/10/2007 3:09 PM |
Thank you for your response. Let me apologize for the confrontational nature of my initial posting; such rudemess was not called for.
That said, I have to wonder about T. Rex's bone structure. Like modern birds, T. Rex's bones are full of air pockets, which create strong structure that is also light. What would be the purpose of such a bone structure if not to allow greater speed than would otherwise be possible? And why would a scavenger need such speed?
I am not a professional paleontologist, nor any kind of scientist; I am, however, an observer and analyzer of evidence (I spent 20 years as a reporter working the police beat), perhaps not the best, but certainly not the worst...I hope.
It seems to me that T. Rex's bone structure indicates that it needed to catch speedy prey at least part of the time. Most scavengers don't need to be light (unless they fly, of course), nor need speed for anything but escape. Obviously, T. Rex did not fly and I can't imagine why it would need speed for escape.
Is it possible that T. Rex was both scavenger and predator? That would seem the most likely case from the available evidence.
BTW, I came across this controversy yesterday on The Science Channel, which was showing a rerun of "T. Rex: Warrior or Wimp?", a show I had never been able to catch before. |
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Re: Bite Marks on Bones |
By Doug Shore on
3/3/2008 1:13 PM |
Mr. Owens,
Speed is relative. Research conducted by John Hutchinson shows that T. rex likely couldn't run more than 15 mph. that's around the speed the average human can run. Now, that seems slow compared to many other predators. But it was fast enough. T. rex's likely targets couldn't run any faster than he could. Further more, the juveniles were slimmer and built more for speed (at least it appears). Couple that with evidence that T. rex very well may have lived in packs. Phil Curry proposes that the juveniles ran down the prey and into the jaws of the larger, more powerful adults. They didn't have to be fast, just fast enough. But the debate of what T. rex did for a living is far from over. |
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Re: Bite Marks on Bones |
By K Coyne on
3/3/2008 1:14 PM |
I too have watched the "T. Rex: Warrior or Wimp?" show, several times now as my son is an avid proto-palentologist at age 5. I have been interested in the debate since I first heard of Dr. Horner's hypotheses regarding T. Rex as a scavenger. While I am not an expert in the field, and indeed have limited knowledge of it, I was interested in certain comments in the show. One of which was the characterization of T. Rex's teeth as unsuitable for predation. This interested me based on my teenage interests in things Medieval. I was a fighter in what is now termed a 'LARP' and fought with a 'great Mace' instead of a sword. The Sword, like the teeth of raptors, is a flat blade and very effective at slicing through light armor and flesh, but relatively ineffective at damaging stronger armor.
In contrast the Mace, and the Great Mace (a larger, heavier version) were effective at crushing bone through the heavier armor of plate mail equipped Knights. The Mace is often attributed to the clergy as it was a weapon that was not designed to draw blood, but was effective in a fight.
Now taking this analogy to the dinosaur arena, we have an interesting point of discussion. The teeth of the smaller known predatory dinosaurs were blade or sword like, while the T. Rex was equipped with bone-crushing semi-conical teeth. I therefore ask the question, if a T. Rex was hypothetically a predator, would it not be a positive evolutionary trait to have developed teeth that were designed to quickly terminate a fight with a heavily armored dinosaur such as a Triceratops by punching through the thick skin and armored bone that they possessed?
It seems to me based on some videos in the 'Tyrannosaurus vs. Triceratops' vein that a fighting Triceratops could possibly shatter several teeth of a T. Rex should it struggle while the T. Rex was biting it.
What good would blade-like teeth be when the battle is between two sizable and strong animals?
While this is not a definite conclusion to the argument, it is at least as far as I am concerned a talking point.
Kevin Coyne
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Re: Bite Marks on Bones |
By Dave Barbara on
4/7/2008 11:43 AM |
With regard to the size and shape of T-Rex teeth, and what they were used for, it might help to take a look at modern day animals. However, even there it can get confusing.
As someone who has a love of the sea, and specifically cetaceans(dolphins, porpoises, and whales) I find the arguments presented here quite interesting.
I urge everyone interested to take a look at the teeth of an Orca (Killer Whale). Curved, semi-conical, not quite dull, but not quite sharp either. Basically they are made for (and used for) grabbing, and ripping. Orcas will eat everything from small fish, to large pinnipeds.(Seals, Sea Lions) Only dead fish if they are hand fed in an aquarium. NEVER in the wild.
Great white sharks have extremely sharp dagger - like teeth, and will eat just about anything in front of them. Small fish to Pinnipeds. Dead or alive. You name it and they will eat it. However only Orcas (In packs) will take on something as large as a whale. A Great White will only eat a dead whale.
Perhaps this is something for people to consider.
Dave Barbara |
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Re: Bite Marks on Bones |
By Erin Fair on
5/22/2008 8:56 AM |
I've always thought that the idea of T.rex being purely a scavenger vs. purely a predator was kind of silly, no offense to anyone of course. As a student of paleontology out in Colorado, I'm always trying to catch up on the latest theories and interesting ideas, but I've really never been interested in this particular "argument" (I guess you can call it).
Seeing what I can about physcial evidence like bone growth around bite marks that seem to fit the bill for Tyrannosaurus rex on other rexes, Triceratops, and various Edmontosaurs kind of tells me that predation was not only possible, but probable.
As for the size of the femur in relation to the rest of the leg, I do like the comment Luke Owens made concerning the air sacs and hollows in the bone structure. Wouldn't that suggest that the animal would be able to at least form a good enough sprint-like run to grab something from an ambush position?
And though I do try to compare dinosaur traits to modern-day dinosaurs like the turkey vulture...don't forget that hawks and eagles are also dinosaurs and have no problem hunting. Also, isn't the new idea regarding dromaeosaur claws and attacks based on cat and bear claw shapes? That's mammalian traits being cast onto dinosaurian traits to me.
I have heard the theory that rex's bite could have been something like a komodo dragon's, where bacteria that is deadly infect the animal and slowly kill it from a single bite. Having enlarge olfactory lobes could make finding this wayward, now dead animal easy for the rex. There's a theory of scavenging and predation in the same sentence, though I know that komodo dragons aren't birds...they're still on the same family tree as the dinosaurs.
Seems to me that it's hard to rule out either option. Both have tons of evidence, so could both be true? I hate lumping everything into a single category.
-Erin |
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Crowds gather around a model of Deinonychus and Tenontosaurus at the Dinosaurs under the Big Sky exhibit opening.
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