Could T-rex Have Been a Persistence Predator?

[Sightreader]

Hello everyone!

I just started learning about dinosaurs and am very excited! I’m trying to grapple with some weird things about the T-rex and was wondering this: could T-rex have been a “persistence” or endurance hunter?

 

I’ve been reading things that say the T-rex was probably slower than most of its prey. Rather than out-sprinting its prey, might T-rex have simply been in “better shape”?  That is, might it have been capable of sustaining an elevated pace far longer than its prey, then relying on superior tracking skills to relentlessly close on hiding prey attempting to cool down and recover from exhausting sprints?  I’ve heard this method proposed for early hominids and wondered if T-rex might also fit the bill, but I really don’t know what goes into a successful “persistence predator”.

 

Thank you all for being understanding - obviously I’m new at this - and thank you especially for not laughing at yet another monumentally uninformed crackpot idea! 

 

https://en.wikipedia.org/wiki/Persistence_hunting

Edited April 25, 2021 by Sightreader
Bad grammar... again.

[Randyw]

Interesting idea... I haven’t really studied t-Rex anatomy so we have got to bring the experts in on this one. @Troodon any thoughts?

[Crankyjob21]

@Randyw I think that T. rex was a ambush predator, and also a scavenger. A animal as big as T. rex could probably have ran fast in short bursts of speed. 

[Randyw]

Wich is also a possibility. But the question on this topic is could it have been an endurance predator. As to wether it could run at all is still up to debate. A lot of the current research is leaning to not being able to run at all and with poor acceleration due to relatively weak bones. But it was strongly muscled, with well developed olfactory lobes in the brain And forward looking eyes wich would all help a scavenger or endurance predator. There is also the possibility it could have delivered a bite then followed the animal until blood loss and/infection brought down the prey..... Relay pack hunting has also been suggested...

 

[fossilsonwheels]

If we look at extant predators, endurance predators share several traits. Wolves, Orca, and African Wild Dogs hunt in groups when engaged in distance pursuits. This type of hunting strategy requires cooperation, endurance, intelligence and athleticism. A wolf pack tracks for a while but once the pursuit is on, they can maintain a pretty surprising speed over distance and then the endurance of a long fight. The 36 hour bison hunt is a great example. Orcas show remarkable stamina and intelligence when on an endurance hunt. All three animals are also intelligent hunters that can improvise and change a strategy very quickly. Each member of the group also has to do his job well to succeed. Tremendous cooperation is required. Chimps do the same thing when they are hunting. Endurance based cooperative monkey hunting while swinging through a dense forest takes a lot of skill and cooperation. Could Trex have the skill set and brain needed? 

A solo wolf or Orca uses different techniques and change prey. They can not really hunt solo in the same manner. I think because it seems T-Rex might have had some athleticism issues to start with and I personally do not think they were pack animals, it would seem unlikely to me that they were endurance hunters. It’s possible I suppose but my thoughts are they may have been similar to Short-faced Bears. The body design and senses suggest a niche as primarily a scavenger, kleptoparasite and just an occasional hunter. 

Just my uninformed opinion lol

Edited April 26, 2021 by fossilsonwheels

[Troodon]

@RandywThoughts? Not really, I don't study the behavior of dinosaurs so anything I say is not based on scientific evidence just my gut which may be completely wrong and misleading to others.  Unfortunately most of us have preconceived views based on very little information.  A paleontologist is best to address these issues.   I enjoy reading their latest research and theories,  my eyes usually roll,  but know that it won't be long before others will come up with new ones, so I dont stress about them.  Just look how many publications came out addressing how the dinosaurs died out, and they keep coming and coming...

[jdp]

Actual paleontologist here. These sorts of questions are very difficult to test and even harder to test rigorously, which is why there is a lot of uncertainty and disagreement between the people who do work on these problems. 

 

In other words, it's possible, but I don't know how you'd test it with any rigor.

[FossilDAWG]

I'm reminded of a talk I saw years ago in which a vertebrate paleontologist speculated at length about how different dinosaurs had sex, complete with multiple drawings of "possible" orientations and positions.  I thought it said more about his fantasy life than it did about dinosaurs.  It's easy to speculate, but unless there is a plausible way to test the speculations they are not science.  How long could a T. rex run for, compared to a Triceratops?  I doubt that information could be tested from the fossil record, unless maybe if you could find a very long trackway with a T. rex skeleton at the end.

 

Don

[jdp]

was this Ken Carpenter by any chance

[FossilDAWG]

That name seems very familiar, yes.  Pretty sure it was.

 

Don

[Sightreader]

Wow, great discussion, and thank you guys SO much for considering this idea!

 

So far, these seem to be the modes of hunting that T-rex could use in absence of competitive speed:

1. Scavenger
2. Ambush predator
3. Persistence predator

Certainly the scavenger would fit very well with what little I know about T-rex. Is there any evidence to the contrary for the scavenger model?  That is, how often do we see T-rex injuries on animals that survived and healed?

 

The arguments I recall for T-rex’s limited speed was that their musculature was insufficient for their size and weight. For ambush predation, what sort of musculature would be needed?  I can’t imagine something as gigantic as a T-rex hiding under a bush; might they have been capable of very short bursts of speed, like crocs or Komodo dragons?  If so, how might that affect their anatomy?

 

Also, thanks for the great information on “persistence predators”.  Sounds like they would need to hunt in packs and not only out-smell their prey, but also out-smart them. Is there anything in the T-rex’s anatomy that would make such traits unlikely?  Would you consider the T-rex’s build cursorial enough to sustain elevated speeds for long periods of time?  Have we ever been able to establish that a species definitely did or did not hunt in packs based purely on fossil evidence, in which case, what was the smoking gun that won the case?

 

Thanks a ton for the great thoughts and being so gracious!

Edited April 27, 2021 by Sightreader
Attempt to increase clarity

[Yoda]

In the book "Why Elephants Have Big Ears - Understanding the Patterns of Life", the author explains why in general, cold blooded animals are sprinters, only capable of quick short bursts of energetic sprinting. And warm blooded mammals are capable of longer more sustained endurance movement. 

 

The debate whether some dinosaurs were warm blooded is ongoing. 

But I guess this would fit in the the OP question

[siteseer]

Maybe with more advances in robotics someone could create a scaled-down version of a Tyrannosaurus and then do some tests with that.  I've always wondered how an animal so big, an adult weighing perhaps 5-7 tons, and on two legs could run with all that stress involved on its legs.  Imagine the sore knees and ankles and possible shin splints.  Imagine the risk of a fall - likely fatal in most cases and maybe a slow death of starvation.  Walking would be better.  With a good sense of smell the animal could find a carcass and its size would allow it to intimidate a smaller predator from its kill.

 

Scientists have looked at ostriches, kangaroos, and roadrunners but there is just noting like a Tyrannosaurus today.  It's fun to think about how it behaved and what it could do when motivated.

[Sightreader]

18 hours ago, Yoda said:

In the book "Why Elephants Have Big Ears - Understanding the Patterns of Life", the author explains why in general, cold blooded animals are sprinters, only capable of quick short bursts of energetic sprinting. And warm blooded mammals are capable of longer more sustained endurance movement. 

Ah... well, as may be painfully obvious, I have only just begun my natural history reading, so I don’t know how that works. I was aware that “cold blooded” animals can do violent bursts of movement, but I don’t know enough about how muscles work to determine if muscles normally used for warm blooded work could also move the huge mass of a T-rex violently and quickly enough to ambush animals that are normally quite a bit faster.

 

And now for the dumbest and least educated observation of all, T- rex simply LOOKS like it’s optimized for energy and speed. I’m not sure how important it would be for a scavenger to be fast and agile: are there scavengers today who are similarly optimized for energy and speed, and if so, what forces drove them to evolve that way?

Edited April 28, 2021 by Sightreader
Shortened to get to the point

[ThePhysicist]

23 hours ago, Sightreader said:

Is there any evidence to the contrary for the scavenger model?  That is, how often do we see T-rex injuries on animals that survived and healed?

Yes. There are several finds of healed wounds clearly resulting from failed T. rex hunts. There's a "famous" hadrosaur vertebra with a tooth stuck in it: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3732924/

 

 

There's also a healed Triceratops brow horn that was bitten off. [Happ, J. 2008. An analysis of predator-prey behavior in a head-to-head encounter between Tyrannosaurus rex and Triceratops, in P. Larson & K. Carpenter (eds.), Tyrannosaurus rex the Tyrant King, Indiana University Press, pp. 355–370.]

 

So clearly it tried to eat living animals. 

 

23 hours ago, Sightreader said:

Have we ever been able to establish that a species definitely did or did not hunt in packs based purely on fossil evidence, in which case, what was the smoking gun that won the case?

In the case of T. rex, there exists no direct fossil evidence of pack behavior. However, there is potential evidence of such behavior in other Tyrannosaurs. Just recently published: https://peerj.com/articles/11013/#utm_source=Twitter&utm_medium=Social&utm_campaign=11013

https://phys.org/news/2021-04-fearsome-tyrannosaurs-social-animals.html

[Randyw]

36 minutes ago, ThePhysicist said:

there is potential evidence of such behavior in other Tyrannosaurs. Just recently published: https://peerj.com/articles/11013/#utm_source=Twitter&utm_medium=Social&utm_campaign=11013

https://phys.org/news/2021-04-fearsome-tyrannosaurs-social-animals.html

Thanks for posting that! That’s what I was referencing but for the life of me I couldn’t find it again when I posted!

 

2 hours ago, Sightreader said:

And now for the dumbest and least educated observation of all, T- rex simply LOOKS like it’s optimized for energy and speed.

Actually the Jurassic park lean mean t-Rex model is falling out of favor. While personally I like it the current research is leaning towards a more walking gut on two legs model... sigh...

This is the representation of sue the t-Rex shown last year some models show it even “fatter”

[Crusty_Crab]

Have you also read Jack Horner's work? He suggests that T-Rex may also have been a scavenger/opportunistic predator based on the large olfactory regions of the brain comparable to that of vultures. As has been brought up though, ascribing complex behaviors to bones is challenging and I think even Dr. Horner brings that up not necessarily that he truly believes it was a scavenger, but to challenge our assumptions about dinosaurs and their behaviors. 

[Sightreader]

On 4/30/2021 at 1:49 PM, Crusty_Crab said:

Have you also read Jack Horner's work? He suggests that T-Rex may also have been a scavenger/opportunistic predator 

I am far too much of a neophyte to have read such a work. I was just wondering if the notion of a “persistence predator” might be a viable alternative to the scavenger hypothesis? 

It sounds like there might be some sort of potential for T-rex pack hunting. However, there are at least two other attributes associated with persistence predation: intelligence and being sufficiently “in shape”. Is there evidence that T-rex simply lacked the brainpower to conduct something as sophisticated as persistence predation? Also, is there any evidence we can point to that supports the “Lazy-rex” reconstruction of their physique? Alternatively, do we have any evidence as to how well T-rex’s most common prey fared on the endurance scale?

 

Thank you guys for bearing with me!

 

Edited May 2, 2021 by Sightreader

[Randyw]

From what I’ve been seeing Sue the t-rexs gastralia (belly ribs) are believed to be showing that they are much more barrel chested then previously thought. See first picture. Left is previous thought. The right is the skeleton with gastralia in place.Also by doing endocasts of the t-Rex skull it is believed to show large olfactory lobes and vision lobes but small “thinking” lobes. (Second picture)

[Randyw]

Compare sues brain endocast to a triceratops. (Below) The triceratops also had large olfactory and vision lobes and small “thinking” lobes.

 

 

Edited May 2, 2021 by Randyw
Wrong picture

[Sightreader]

Fascinating!  Both of the heavier build and the intelligence comparison versus Triceratops would seem to suggest that this “persistence predator” hypothesis is less likely although, like most of this fossil stuff, it feels like there’s never enough evidence to rule anything out.

 

Perhaps it’s just Murphy’s Law, but it always feels to me like paleontological evidence always favors whatever make the least possible sense.  I would also guess, as a corollary to Murphy’s Law, that if one were to actually go there and see such animals in action, the answers to such confounding mysteries would suddenly be so painfully obvious that everyone would feel foolish, but perhaps such pessimism only shows how naive I am.

 

At any rate, thank you everybody for such wonderful insights!

Edited May 2, 2021 by Sightreader

[Norki]

I think that the solution to this question is fairly simple if you consider the basic anatomy of most persistence predators, which is typically lean and gracile, with smaller muscles that are built for prolonged use. T. rex was extremely bulky, and the legs seem better designed for short bursts of powerful energy, which to me suggests an ambush predator.

 

I remember reading once that the serrations in theropod teeth are also theorized to have been shelters for bacteria, which would cause infection in animals that were bitten, much like modern komodo dragons. I think that the most likely hunting strategy for T. rex would have therefore been short, powerful ambushes, and then persistence stalking only if the injured animal got away and began to succumb to infection.

Edited May 3, 2021 by Norki