Tyrannosaurus Tooth Found Embedded in Hadrosaur Tail

[Simon]

WELL!

I do HOPE that this latest find puts to bed for all time the question of whether TRex was a ... MEAT eater?

..running away... 

[Dinoguy2]

I absolutely fail to see any harm in concluding that it was indeed predation. None whatsoever.

I'm with a lot of paleontologists who are completely sick and tired of the whole predator/scavenger debate.

The thing most paleos are sick of is the media portraying the idea that there IS a predator/scavenger debate. Jack Horner himself admitted rex was an opportunist years ago, based on healed hadrosaur tail bites. No scientist on earth believes T. rex was a scavenger. The debate doesn't exist, yet news sites pretend it does to make an exciting sorry that will sell ads.

Bitten and healed hadrosaur tail vertebrae exactly like this (except preserving the actual tooth itself) are known from several specimens, the first described in the '90s. There are so many specimens showing T. rex tried and failed to bite hadrosaur tails that scientists like Andrea Cau are currently working on papers suggesting not only that T. rex hunted, but we have enough evidence to show HOW it hunted--that is, it probably went after the tail in an attempt to bite/cut the muscles anchored to the leg, basically crippling them. The healed specimens are the ones that missed the tail base.

In case you needed more evidence, here's a famous painting showing T. rex hunting hadrosaurs by biting the tail, based on these types of fossils, from the early 1990s!


How many news sites reporting this story talk about the fact it is old news and similar specimens have been found several times before? None.

The question "was T. rex a scavenger?" only exists as a marketing tool, it's nowhere near science and hasn't been for almost a decade.

It's bad enough that Jack Horner is so stricken by hubris that he refuses to accept any argument that contradicts his "theory" (and no one should forget that he's never had the dedication or the courage to actually produce a proper paper on it).

"Horner himself has claimed that he never published this idea in the peer reviewed scientific literature and used it mainly as a tool to teach a popular audience, particularly children, the dangers of making assumptions in science (such as assuming T. rex was a hunter) without using evidence." http://en.wikipedia.org/wiki/Tyrannosaurus#Feeding_strategies

Horner doesn't believe it, and he "says" he never 'really' believed it, but said it as away to get young kids thinking critically bout their assumptions. Obviously, that backfired...

anyway, you're getting your info from old sources. Jack Horner currently believes T. rex was a hunter. He has admitted he was wrong about the scavenger thing many times, in public, over the last few years, which is why he hasn't published a paper on a theory he doesn't believe in. "Hubris" and lack of courage have nothing to do with it.

Whether or not you believe him when he says the whole thing was just a thought experiment for kids (I don't, he seemed pretty serious about it 20 years ago), he is on the record saying he was wrong. Obviously it will take another 20 years for the internet to realize that fact...

[Seijun]

Thanks for the info dinoguy, I had no idea that similar specimens had already been found

[Gwangi]

Maybe Tyrannosaurus didn't hunt and kill its food but rather would only bite off the tail and eat that, making Tyrannosaurus more of a parasite than a predator. Since dinosaurs were giant lizards it is likely that these hadrosaurs grew their tails back so this predation was ultimately harmless and always guaranteed a meal for the Tyrannosaurus. Maybe the Tyrannosaurus was even a hadrosaur mimic and had matching coloration so it could more easily navigate through the herd looking for its next victim.

There we have it, I nailed it, I'll expect my honorary PhD in the mail any day now.  Seriously though, that kind of hunting behavior is not unheard of in the animal world but I'm obviously just kidding here.

Brian Switek actually did a great write up about this "debate" on his blog recently. Worth reading.

Time to Slay the T. rex Scavenger "Debate"
http://phenomena.nationalgeographic.com/2013/07/16/time-to-slay-the-t-rex-scavenger-debate/

[Simon]

[suspsy]

I absolutely fail to see any harm in concluding that it was indeed predation. None whatsoever.

I'm with a lot of paleontologists who are completely sick and tired of the whole predator/scavenger debate.

Bitten and healed hadrosaur tail vertebrae exactly like this (except preserving the actual tooth itself) are known from several specimens, the first described in the '90s. There are so many specimens showing T. rex tried and failed to bite hadrosaur tails that scientists like Andrea Cau are currently working on papers suggesting not only that T. rex hunted, but we have enough evidence to show HOW it hunted--that is, it probably went after the tail in an attempt to bite/cut the muscles anchored to the leg, basically crippling them. The healed specimens are the ones that missed the tail base.

In case you needed more evidence, here's a famous painting showing T. rex hunting hadrosaurs by biting the tail, based on these types of fossils, from the early 1990s!

Why are you presenting all this to me? I'm very well aware of those of fossils, and that superb Brian Franczak painting, thank you.

"Horner himself has claimed that he never published this idea in the peer reviewed scientific literature and used it mainly as a tool to teach a popular audience, particularly children, the dangers of making assumptions in science (such as assuming T. rex was a hunter) without using evidence." http://en.wikipedia.org/wiki/Tyrannosaurus#Feeding_strategie

Well aware of that segment of the wikipedia entry as well . . .

Horner doesn't believe it, and he "says" he never 'really' believed it, but said it as away to get young kids thinking critically bout their assumptions. Obviously, that backfired...

And yet he has consistently contradicted himself throughout the years by stating that T. rex was indeed 100% scavenger and that there is no evidence of predation at all. He's said it at appearances as reported by the BBC and Prehistoric Times. He says it on the DVD Special Features for JP3. Heck, at one point, he even devised an entire travelling museum exhibit about it. He even thought it fit to position himself as the prosecutor and the judge.

http://www.sdnhm.org/archive/exhibits/trex/overview.html

http://news.bbc.co.uk/2/hi/science/nature/3112527.stm

If Horner doesn't really believe that T. rex was a scavenger and never did, then he's been terribly irresponsible over the years. He has directly created a controversy where there should never have been one. A controversy that has, quite conveniently, earned him a lot of publicity.

anyway, you're getting your info from old sources. Jack Horner currently believes T. rex was a hunter. He has admitted he was wrong about the scavenger thing many times, in public, over the last few years, which is why he hasn't published a paper on a theory he doesn't believe in. "Hubris" and lack of courage have nothing to do with it.

You call this an old source?
http://www.redorbit.com/news/science/1112898395/t-rex-embedded-tooth-prove-predator-071613/

The fossil evidence only "shows that a T. rex bit a live duckbill dinosaur. There's no evidence that it was chasing it," Horner said.

In keeping with scenarios, Horner added his speculative theory: "A T. rex could have walked up to a sleeping duckbill dinosaur and bit it, realized it was alive, and then backed away," he said. "That's just as plausible as saying that it's chasing it because there's no evidence for either one."

Do I really need to point out how lame a speculative theory that is?

[wings]

...Bitten and healed hadrosaur tail vertebrae exactly like this (except preserving the actual tooth itself) are known from several specimens, the first described in the '90s. There are so many specimens showing T. rex tried and failed to bite hadrosaur tails that scientists like Andrea Cau are currently working on papers suggesting not only that T. rex hunted, but we have enough evidence to show HOW it hunted--that is, it probably went after the tail in an attempt to bite/cut the muscles anchored to the leg, basically crippling them. The healed specimens are the ones that missed the tail base.

The "chevrons" do not fuse with the tail vertebrae, so they are often missing or become disarticulated. Isn't all we have on the current paper is the two fused tail vertebrae? The chevrons belongs to this area could well be disarticulated as of the rest of the tail is missing as well...

It sounds to me that where the bite would landed really depends on the height of the animal. For example DMNH 1493 (Edmontosaurus annectens) and JRF 1002 (Brachylophosaurus cf. canadensis) have their neural spines bitten off therefore these bites are coming from the top instead of the base. This probably suggest that they are just going for the tail but not necessarily just the base (as seen on these "healed" specimens). There is also a hadrosaurid tail vertebra (CPC-309) showing bite mark at the base and that was attributed to the genus Deinosuchus sp.

[Dinoguy2]

In keeping with scenarios, Horner added his speculative theory: "A T. rex could have walked up to a sleeping duckbill dinosaur and bit it, realized it was alive, and then backed away," he said. "That's just as plausible as saying that it's chasing it because there's no evidence for either one."[/i]

Do I really need to point out how lame a speculative theory that is?

It's less plausible, but still a possibility. While he's being very extreme just for the sake of stirring up controversy, I'm guessing his point is that it's too easy to read into evidence based on preconceived stories.

Previous studies have suggested that large carnivorous dinosaurs would have preferentially hunted small or juvenile prey, rarely attacking large adults. with that in mind, it's easy to suspect that some bit marks on large adult prey could have been accidental, defensive, territorial warning shots, etc., rather than active hunting for food. But, given the amount of evidence for T. rex specifically, that seems pretty unlikely.

It is completely fair, though, to point out that alternatives are possible and that there is never "definitive" evidence hen it comes to behavior in dinosaurs.

From the article:
""My argument has always been that T. rex is [an opportunist] like a hyena," he added.

But DePalma and colleagues refute Horner's idea. "

That is nonsensical. How do bite marks refute the idea that it was an opportunist like a hyena, which like all carnivores both hunt and scavenge? These scientists seem not to know or care what each others current arguments are. They're saying the same thing in different ways and calling each other out over it (unless it's just bad reporting, which seems more likely).

[wings]

Previous studies have suggested that large carnivorous dinosaurs would have preferentially hunted small or juvenile prey, rarely attacking large adults. with that in mind, it's easy to suspect that some bit marks on large adult prey could have been accidental, defensive, territorial warning shots, etc., rather than active hunting for food...

...it probably went after the tail in an attempt to bite/cut the muscles anchored to the leg, basically crippling them. The healed specimens are the ones that missed the tail base...

I assume that you are not talking about the tail base being bitten off completely since that would imply the whole tail came off. Are you talking about the tail base as where the "chevrons" are or you are talking about the base of the tail as in near the hips? If we are just referring to the tail base being bitten; these healed specimens do have bite marks on them at/near the tail base (on the neural spines) but perhaps they are lucky or these bites are not deep enough to cripple them. These bites might not be as accidentally placed as you think; as you can see from here (http://dinosaurpalaeo.wordpress.com/2011/10/04/dinopic-of-the-day-9-ouch/) that biting from the top (at the tail base near the hips) is a perfectly fine method in disabling the animal. The bite was aiming at the muscles on the top half of the tail rather than the muscles anchored to the legs...

[suspsy]

In keeping with scenarios, Horner added his speculative theory: "A T. rex could have walked up to a sleeping duckbill dinosaur and bit it, realized it was alive, and then backed away," he said. "That's just as plausible as saying that it's chasing it because there's no evidence for either one."[/i]

Do I really need to point out how lame a speculative theory that is?

It's less plausible, but still a possibility.

Any tyrannosaur that came across an intact duckbill corpse (which would have a distinct odor to it) would absolutely not bite into the tail first. It would tear open the body cavity to get at the liver, heart, lungs, and other vital organs. Only after those were consumed would it start feeding on muscle tissue. That's the M.O. of all large land carnivores alive today, and there's no reason why tyrannosaurs would be any different. The only way for Horner's "speculative theory" to be possible would be if the tyrannosaur was blind, deaf, and unable to smell anything.

While he's being very extreme just for the sake of stirring up controversy, I'm guessing his point is that it's too easy to read into evidence based on preconceived stories.

That argument can be turned right back on Horner in a snap, and more effectively to boot.

From the article:
""My argument has always been that T. rex is [an opportunist] like a hyena," he added.

I've already shown that Horner is either absent-minded, dishonest, or very quick to change his mind.

I will say, if I ever do have the opportunity to meet Horner face to face, the one question I'd ask him is: why did he only ever single out T. rex for the obligate scavenger hypothesis and never Giganotosaurus, Carcharodontosaurus, or Mapusaurus?

[Seijun]

Any tyrannosaur that came across an intact duckbill corpse (which would have a distinct odor to it) would absolutely not bite into the tail first. It would tear open the body cavity to get at the liver, heart, lungs, and other vital organs. Only after those were consumed would it start feeding on muscle tissue. That's the M.O. of all large land carnivores alive today, and there's no reason why tyrannosaurs would be any different.

Unless there were two tyrannosaur, and the second was trying to steal the kill from the first?

[amargasaurus cazaui]

Just a log or two to toss into the fire here. Horner Chose Tyrannosaurus to be  the object of his comments because he was posing comments regarding his experiences with the Jurassic Park movie, and some of the issues he took with how the dinosaur was portrayed. That is the basic reason he chose Tyrannosaurus .
    As to the debate here about the bite and the tail and so forth. There is another argument that is quite reasonable to suggest as well. Rather than biting into the carcass or innards as mentioned....etc.
All of this back and forth assumes  the undisturbed feeding of a large predator. If the Tyrannosaurus were rushed, somehow in danger or needed to hit and run it is quite possible the dinosaur might shear off or attempt to tear off a section to carry off to a safer spot to consume.Or, even perhaps consider the idea of carrying the torn away section to an injured mate, or freshly hatched chicks for that matter. Such behaviors at times are inferred from the record....ie. Big Al, and his injuries.

[suspsy]

Unless there were two tyrannosaur, and the second was trying to steal the kill from the first?

So now two tyrannosaurs are mistaking a sleeping duckbill for dead? Either tyrannosaurs were improbably dense or duckbills were very heavy sleepers.

Just a log or two to toss into the fire here. Horner Chose Tyrannosaurus to be  the object of his comments because he was posing comments regarding his experiences with the Jurassic Park movie, and some of the issues he took with how the dinosaur was portrayed. That is the basic reason he chose Tyrannosaurus .

No, Horner's obligate scavenger hypothesis dates back to 1990, three years before Jurassic Park.

   

As to the debate here about the bite and the tail and so forth. There is another argument that is quite reasonable to suggest as well. Rather than biting into the carcass or innards as mentioned....etc.
All of this back and forth assumes  the undisturbed feeding of a large predator. If the Tyrannosaurus were rushed, somehow in danger or needed to hit and run it is quite possible the dinosaur might shear off or attempt to tear off a section to carry off to a safer spot to consume.Or, even perhaps consider the idea of carrying the torn away section to an injured mate, or freshly hatched chicks for that matter. Such behaviors at times are inferred from the record....ie. Big Al, and his injuries.

Again, if it wanted to take food to a mate or offspring, it would have gone for the best selection available.

Let's assume that a young tyrannosaur comes across an intact dead duckbill. It needs as much protein as possible to continue to stay growing and healthy. There are adult tyrannosaurs in the area and they are probably on their way right now. So what does the young tyrannosaur do?

A) Quickly tear into the body cavity, consume as much liver as possible, and abandon the carcass only when an adult tyrannosaur appears?

B) Tear a single chunk off the tail and abandon the carcass right then and there?

[Dinoguy2]

I've already shown that Horner is either absent-minded, dishonest, or very quick to change his mind.

Maybe. More charitably, his real MO seems to be trying to inject the scientific method into paleontology, which has a terrible reputation among the other sciences as  being full of speculation and just-so stories. People find a fossil with evidence of behavior and invent a reasonable, most-likely scenario to explain it. Bitten and healed hadrosaur tail? Probably failed predation.

But that is not in any way science.

A scientist would look at that and say, "could be failed predation. Now let me try to prove myself wrong by thinking of other alternate explanations and attempt to rule them out."

The authors of this paper don't seem to have done that. They took the first step of the scientific method, formed a hypothesis, and then *stopped*! Horner is simply taking the next step and proposing an alternative. Is it possible to test any of these? Maybe not. But it is critical for public education that people understand the difference between science and educated speculation.

Are Horner's alternatives more likely? Of course not. But in order to qualify as science, they need to be ruled out using data, not thought experiments. Only then can the hypothesis (T. rex predation on this tail vert) be supported.

[Simon]

Horner has shown himself to be the most adept paleontologist at getting attention and, consequently, $$$ for his work.

His primary interest is in hadrosaurs.  The TRex sideline enabled him to get attention and $$$.  Lets hope that his non-Trex work is still solid.  Probably so, if only because its been going on "under the radar" of ridiculous publicity.

He is not a fool as far as I can tell, and has always tried to keep some "plausible deniability" between himself and dubious "theories" such as the TRex scavenger business.  IE didn't he use a grad student to float that one initially? 

The "theory" has been chewed on and found to be - charitably said - implausible.  I don't think he's a bad guy.  He just sacrificed some short-term credibility for fame and (one hopes) $$$ for his real work. 

And he did find the largest Trex to date ("C-Rex"), 10% larger than "Sue" but sadly an incomplete specimen.

[Seijun]

Unless there were two tyrannosaur, and the second was trying to steal the kill from the first?

So now two tyrannosaurs are mistaking a sleeping duckbill for dead? Either tyrannosaurs were improbably dense or duckbills were very heavy sleepers.

I thought we had moved on to discussing bite marks on "already dead" hadrosaurs.

[amargasaurus cazaui]

Acually the theories about Tyrannosaur as a scavenger date back to 1917 , however Horner entangled himself with the debate  as shown here.
     "  Experts continually debate where the tyrannosaurs were hunters, scavengers opportunistic feeders.  The discussion about the feeding patterns of T. rex and other large carnivorous dinosaurs remains active. Most paleontologists have portrayed them as highly active predators, while others see them as obligate scavengers (Lambe 1917; Colinvaux 1978; Halstead and Halsted 1981; Barsbold 1983; Horner and Lessem 1993; Horner 1994; Horner and Dobb 1997). The scavenger hypothesis has been re-proposed by Jack Horner in the 1990s and appeared in Horner's 1993 book "The Complete T. rex". 


"Twenty years ago, at the first ever Dino Fest event at Indiana University-Purdue University at Indianapolis, the famous paleontologist Jack Horner stood before a crowd of dinosaur fans to deliver his talk "Steak Knives, Beady Eyes, and Tiny Little Arms (A Portrait of T. rex as a Scavenger)." In his estimation, our favorite dinosaurian carnivore looked like the antithesis of an active predator."


Twenty years ago would be 1993 according to my math. He then published a book, "The Complete T-Rex " in which he continued to dissect the topic. So , his delivery of the topic in both print and lecture appear DIRECTLY after Jurassic Park as I earlier stated. The implication is that Horner decided on this approach during the production of and release of Jurassic Park and not years earlier.
 
To answer your choice, I somehow do not get the logic in why it would easier to stand there eating liver, rather than removing a tail or section to carry back to its mate or chicks. It would make FAR more sense to shear off a piece it could carry than stand there eating ? As Hunters we ourselves sometimes take down an animal, remove a leg or choice piece and leave the carcass. There are also previous fossil finds that seem to suggest this behavior, as well as many hadrosaurs that have been found missing, yes, only  the entire tail.
In the  end it becomes a debate about how leisurely the consumption might be and the Tyrannosaurs motives for tearing apart the dead duckbill. If the predator were in  danger, or felt somehow rushed it would be far more likely to just tear away the easiest piece and leave.

[suspsy]

Why couldn't the T. rex take a portion of the liver to its family instead of the tail?

[amargasaurus cazaui]

Why couldn't the T. rex take a portion of the liver to its family instead of the tail?

err.....have you ever tried holding or carrying a piece of liver? It isnt as easy as it might sound. Aside from the idea far easier to grab a larger piece of the animal that would provide more food.

[wings]

...The authors of this paper don't seem to have done that. They took the first step of the scientific method, formed a hypothesis, and then *stopped*! Horner is simply taking the next step and proposing an alternative. Is it possible to test any of these? Maybe not. But it is critical for public education that people understand the difference between science and educated speculation.

Are Horner's alternatives more likely? Of course not. But in order to qualify as science, they need to be ruled out using data, not thought experiments. Only then can the hypothesis (T. rex predation on this tail vert) be supported.

Perhaps they can't see any other viable alternatives... they mainly based their reasoning on observation of modern animals; in the paper they said: "...The localization of the tyrannosaur tooth in the midcaudal area of the hadrosaur is consistent with that noted in modern pursuit predator attacks. Kalahari lions have been observed to initially target the hindquarters of the prey animal, in an attempt to immobilize it...". Their finding is very similar to Carpenter (1998, 2013), Murphy et al. (2013) and probably some of the papers listed in the reference section. For the time being we'll just concentrate on these "tail" bites. Hadrosaurians' tails seems to be quite inflexible (Paul 2010) since part of their tails were stiffened by ossified tendons. So their tails are unlikely to be much of a weapon (unlike the hypothesis of the whip-like tail of the sauropods). Would they have tried to confront a tyrannosaur with their back side? Isn't it unusual if they are not facing each other in a "fight" if that is the case? If they are facing one another then why the tyrannosaur would try to bite the back end instead of the front of the animal? These bites are on the rear of the animal so it is likely that when the incident occurred the hadrosaur is running/walking away from the tyrannosaur. I don't know whether this is good science or not but at least they seem to find similar modern examples to support their claim as we don't really have much examples of otherwise/alternatives reported or published to go by yet.