Juvenile prey preference in large theropods

[Hieu Nguyen]

In paleontological literature, usually by Dave Hone, I have often seen his hypothesis that large theropods, even tyrannosaurs and carcharodontosaurs, would have mostly targeted juvenile animals (~500kg in weight, based on Hone's Tyrannosaur Chronicles). Before I ask my question regarding this hypothesis, I want to make clear that I am trying to argue or disagree with the main conclusions reached by Hone and Rauhut, 2009. 

A point that Hone frequently brings up in both online discussions/talks and books is that modern predator-prey patterns support his hypothesis, that the vast majority of predators take significantly smaller prey. However, based on studies on large, endothermic terrestrial predators (which I think are most analogous to large theropods), there seems to be overwhelming evidence that they prefer prey close to their own size. Even some literature cited by Hone in support of his hypothesis (Energetic constraints on the diet of terrestrial carnivores by Carbone et. al., 1999 for example) notices that larger terrestrial predators prefer prey nearly their own size. With this in mind, is it inaccurate to say that modern predator-prey patterns support Hone's hypothesis, as he often states? 

[Hieu Nguyen]

Correction: *not trying to disagree or argue! 

[Skye McDavid]

I'm not Dave, but I have discussed this with him on many occasions and we generally agree, so here's my take:

Megafaunal herbivores are very big, so if you are a large terrestrial predator that likes to take on prey similar in size to yourself, juveniles of these megafaunal herbivores may be the best targets.

In the case of extant large endothermic terrestrial carnivores (e.g. Pantherines, wolves) they do preferentially hunt juveniles, often because the adults of those species are considerably larger than the predators. Lions do preferentially target juvenile zebra, and wolves do preferentially target juvenile moose. 

Even for a tyrannosaur, an adult hadrosaur may have been dauntingly large, much as adult moose are for wolves. 

So modern predator-prey dynamics absolutely support this hypothesis.

Skye McDavid
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On Mon, Dec 22, 2025, 10:45 AM Hieu Nguyen <hieu.ng...@gmail.com> wrote:

In paleontological literature, usually by Dave Hone, I have often seen his hypothesis that large theropods, even tyrannosaurs and carcharodontosaurs, would have mostly targeted juvenile animals (~500kg in weight, based on Hone's Tyrannosaur Chronicles). Before I ask my question regarding this hypothesis, I want to make clear that I am trying to argue or disagree with the main conclusions reached by Hone and Rauhut, 2009. 

A point that Hone frequently brings up in both online discussions/talks and books is that modern predator-prey patterns support his hypothesis, that the vast majority of predators take significantly smaller prey. However, based on studies on large, endothermic terrestrial predators (which I think are most analogous to large theropods), there seems to be overwhelming evidence that they prefer prey close to their own size. Even some literature cited by Hone in support of his hypothesis (Energetic constraints on the diet of terrestrial carnivores by Carbone et. al., 1999 for example) notices that larger terrestrial predators prefer prey nearly their own size. With this in mind, is it inaccurate to say that modern predator-prey patterns support Hone's hypothesis, as he often states? 

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[Hieu Nguyen]

Thank you for the input, I wonder if you can link some studies that show juvenile animals making up a significant portion of pantherine cats and wolves' diet? Juveniles are of course easier prey yes, but I do wonder given modern mammalian herbivores produce enough offsprings for juveniles to be always an option? The studies that I am aware of for hyenas, tigers and lions suggest that they primarily target prey roughly their own size or larger. 

[Hieu Nguyen]

Oh and - I missed the part which you mentioned that juveniles of large herbivorous dinosaurs being the best target choice for large theropods that take equally sized preys. With say, T. rex (which is 5-10 tons depending on the estimate), wouldn't a similarly sized Triceratops or Edmontosaurus at least a subadult? I thought that Hone meant juveniles as in vastly smaller dinosaurs, being ~500kg as he mentioned in Tyrannosaur Chronicles. 

On Monday, December 22, 2025 at 11:02:58 PM UTC+7 Skye McDavid wrote:

[Skye McDavid]

Here are two examples I found rather quickly. 

For wolves: https://doi.org/10.2981/07-096

"The consumption of roe deer and wild boar increased during the birthing season, probably because of the higher vulnerability of newly born animals; wolves predate mainly on juvenile roe deer and wild boar."

For Lions https://journals.co.za/doi/pdf/10.10520/AJA052550590_750

The lion one is especially interesting since the lions in their sample overwhelmingly favored juvenile over adult buffalo, but this preference is not seen in wildebeest which are quite a bit smaller than buffalo. 

Also, keep in mind that many studies use reference values for the mass of prey species. So if a study says that tigers prefer predator:prey mass ratios of 1:1 (e.g. https://doi.org/10.1111/j.1469-7998.2011.00871.x) this means that tigers prefer prey animal species whose adult size is close to theirs, not necessarily that they prefer individuals their own size. 

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[Skye McDavid]

words like "juvenile" and "subdault" are vague and have inconsistent, sometimes overlapping meanings so they are really only useful for conveying broad strokes without more precise (usually study-specific) definitions. 

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[Hieu Nguyen]

Thanks again. Just to clarify, I did not mean that predators did not prefer juveniles, rather I meant that they do not necessarily prey on vastly smaller juveniles significantly more often than they do on adult herbivores, which Hone seems to strongly support. I remember him stating that preying on an equally large herbivore would have been an one-in-a-lifetime occurance for theropods, which doesn't seem to be supported by current studies. Again, I'm not disagreeing with his other findings and conclusion, my main point is that the statement that modern predation patterns strongly supports his hypothesis doesn't seem true, and it looks like it only partially supports it at best? 

[Hieu Nguyen]

I agree on the vagueness in definition, however (correct me if I'm wrong), what Hone is suggesting is that large theropods would have preyed on vastly smaller animals, not animals roughly their own size (as say, wildebeests are to lions or certain deer species to tigers). 

[Skye McDavid]

That has not been my understanding of any work of his that I have read. Rather, my understanding is that he suggests they would have favored smaller, younger individuals of species within roughly their own size category.

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[Hieu Nguyen]

One further note: I see in the wolf study that they do indeed prefer smaller preys, however this I think is only one case study and broader reviews do not seem to note a particular significance of juveniles in the diet of modern large carnivores? 

[Hieu Nguyen]

I see - I shall attach a few statements by Hone that seems to suggest so. 

[Hieu Nguyen]

These are what I can find so far, Hone seems to suggest that large theropods preferred, I quote, "substantially smaller prey" and not prey roughly their own size like modern large predators. 

[Hieu Nguyen]

Oh - not just preferred, but preying on them the majority of the time. 

[Skye McDavid]

*substantially* does not mean *vastly*

Aside from that I think you are just reading too far into what I would read as hyperbole for emphasis. 

Skye McDavid
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[Hieu Nguyen]

That's more semantics, I think, and going by provided numbers (~500kg for a juvenile), that's still much smaller than expected for modern carnivores - only one tenth the size of the largest theropods. As for hyperbole - I'd say then it probably can be very misleading when the purpose is science communication, but that, again, is another matter. 

[Michael Willis]

I think we need to be careful in saying Hones work is accurate or inaccurate one way or the other. We are, after all, discussing the hunting preferences of extinct animals. Whilst we can be informed, nobody will ever truly know. 

There are several examples in extant reptiles of prey size scaling with body mass, even in an intraspecific sense. Komodo dragons are one example, as are numerous crocodilian species. Komodos will shift to target much larger prey later in ontogeny once going through their own large size increases (e.g. V komodoensis  (70kg to 80kg) targeting large ungulates (300kg - 500kg) as adults), whilst also opportunistically feeding on smaller prey - even smaller komodos. It's not outside the realm of possibility that theropods had similar habits - large theropods targeted larger prey to meet their energetic requirements, but also took the easy route and hunted a juvenile should the opportunity present. Smaller theropods may have hunter smaller prey in line with their predation ability, and reduced energetic needs. True, the endothermic/ectothermic argument comes into play as I note previously that mammalian carnivores were mentioned in this thread, but until a large zoological thermometer can be inserted into a non-avian theropod, I think it's worthwhile considering the ectotherms here too. 

Tyrannosaurus was mentioned so I'll respond in the context of tyrannosaurids here; direct predation evidence in tyrannosaurids (such as the lovely fused hadrosaur caudals still containing a tyrannosaurid tooth - DePalma II et al, 2013 (worth a read if you haven't )) is rare, and attributing the most common signal we have (bite marks) to pre or post mortem is difficult. You certainly cannot reconstruct the entire prey preference of any tyrannosaurid based off the evidence we have. Prey size and niche dynamics are complex and, until we have a much larger sample size of theropod gut contents suitable to perform histological analysis to definitely say exactly what they were eating (we can dream), it will be very difficult for anyone to confidently say one way or the other exactly what dietary preferences were. 

Great discussion to have though. 

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[Hieu Nguyen]

I appreciate the response, though that's not related to the discussion I believe. I wasn't questioning Hone's conclusion but rather an aspect of his work. 

[Milo Gaillard]

To Michael,

You make plenty of excellent points here. I will say that it sometimes is possible to determine whether those instances were predation or scavenging events. For example, the instance of a Tyrannosaurus rex tooth being inside an Edmontosaurus caudal was one where bone grew over the caudal, indicating that the individual was still healing when the tooth was in. This means that the Edmontosaurus was still alive, which means that the Edmontosaurus was most likely hunted by a T. rex

Just wanted to say that.

-Milo Gaillard

Sent from my iPhone

On Dec 22, 2025, at 12:10, Michael Willis <m.cwil...@gmail.com> wrote:



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[Tristan Stock]

I wanted to point out a few things about the extant carnivore literature that could be relevant to this topic.

First is that there is a difference between “most taken” prey and “preferred” prey. Amur tigers in Sikhote-Alin Zapovednik hunt mostly adult elk, which are one of the more abundant herbivores on the landscape and a bit larger than the tigers. However, when they are available, they much prefer hunting rarer wild boar with a selective preference of over 6x. They also don’t just like smaller prey in general, as they select against taking sika, roe, and musk deer that are all smaller than the tiger, despite sika being much more common than boar or elk in parts of their range, so there is a clear selective choice on the part of the tigers to want to take down boar (Miquelle et al. 2010). Recent work has also shown similar trends with adult saltwater crocodiles in Kakadu National Park with regards to abundant prey that make up most of their diet (fish and other aquatic animals) vs preferred prey they select for (feral pigs) (Adame et al. 2018).

Similarly Hunter & Hamman reported in their 2008 book Cheetah that Phinda populations of cheetah feed primarily on nyala, which are woodland antelope around 2x the mass of even the largest toms and well above their preferred size range. However, cheetahs preferably take much smaller reedbuck, which are much rarer on the landscape, but when they are available, they select for them nearly 8x more often than nyala. In another example, Jaguars across their range actually preferentially hunt large mammals (e.g. anteaters, capybara, etc.) over much more commonly taken small forest animals, likely because their primary prey were wiped out during the end-Plesiotocene extinctions and are currently “making do” with suboptimal prey items (Hayward et al. 2016). This is also why I'm a bit skeptical of isotope and bite mark studies that claim extinct carnivores "preferred" certain prey types. All you're really seeing is that that population (or individual in the worst cases) is eating a lot of X animals for whatever reason. For all we know, T. rex might've actually preferred eating large caegnathids or thescelosaurs in its environment due to behavioral or physiological traits that make them ideal to catch, but maybe those animals are harder to come by than juveniles of the large Hell Creek Cerapodans, hence our current bite record data. (Should note that said data could also be skewing the megatheropod bite record towards larger prey items because smaller prey species will likely have their bones pulverized during consumption or be swallowed whole.)

Second is regarding optimal foraging theory and what is driving these animals to hunt specific prey, large or small, because yes a small animal is much safer to catch, but as Nyugen pointed out it is also a much smaller meal that the large carnivore expended energy on. Lions have this problem the worst among big cats because their prides means that they often have to share meals that would normally only feed a single adult individual in another big cat species, like tigers, which means they need to hunt much more frequently over larger areas. Hunting parties of lions rarely exceed four individuals to get the most out of each kill in terms of energy expenditure, and even then lions are often just as successful in killing their primary prey items solo rather than in a pride (Fryxell et al. 2025). The latter point is actually a common trend across many large extant carnivores: spotted hyena hunting success peaks at two individuals cooperating (Smith and Holecamp 2023), and in grey wolves the success rate when hunting deer (elk, moose, etc.) depends mostly on fitness of the pack's biggest male, with only marginal increases in success from large pack size (Sand et al. 2006). (Side note: this is part of the reason why a lot of recent papers have criticized the idea that pack hunting is an adaptation in carnivores to increased hunting success, but instead might be an adaptation to protecting a larger territory with more prey to pick from, or potentially increasing the number of species you can reasonably target.)

So for juvenile dinosaurs to really be the sort of primary prey for adult megatheropods, my assumption would they either need to be fairly large juveniles (e.g. Mapusaurus hunting elementary age Argentinosaurus of a couple tons in weight), or if they're aiming smaller, they'd need to be super abundant and (key thing) easy to safely procure, as juvenile mammals and archosaurs are often not ideal targets when parents are present. (Savuti and Zakouma elephant-hunting lions prefer going after recently independent subadults because calves are so fiercely protected by the herd, and juvenile alligators and gharials are rarely taken during the first few weeks to months after hatching and only start seeing predation pressures post-independence.) I'm not aware of any papers that really dive into what an expected juvenile population of dinosaurs would look like at any given time (please send me some if you know of any!), but assuming an endothermic metabolism a megatheropod would need to eat several hundred kilograms per day based on the work by Barrick and Showers (1999) and that's the bare minimum. They likely would've preferred to consume more given extant large carnivores like to gorge in one sitting and rest off the meal, something we also have evidence for in large theropods given their mobile gastralia to accomodate large meals. In that way I think Hone's model is perfectly valid, especially if they are primarily going after larger juveniles, although seeing population work showing exactly how many juveniles in that size range you'd expect to find on the landscape would be nice. As with everything though I also expect this to vary quite a lot depending on the taxon, environment, behaviors of the prey and predator species, etc. Extant animals are very adaptable in surprising ways and there's no reason to think large macropredatory theropods would be rigidly limited in what they frequently target.

Rambling over.

- Tristan

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[Hieu Nguyen]

Thanks for the papers Tristan - that is very detailed! I am not sure if Hone ever suggested that larger juveniles would be primarily taken, most of his written work seems to suggest that megatheropods primarily take smaller juveniles - "substantially smaller" animals, as he often writes. 

[Michael Habib]

Some notes here, as this is something I have worked a bit on and also discussed at length with Dave Hone:

- There is indeed a (weak) trend towards proportionately larger prey taken by larger living mammalian predators, but this is heavily driven by big cats, which happen to be unusually well adapted to taking large prey. Even then, it’s unclear that they “overwhelmingly” prefer prey near their own size - there’s some data on solo hunting by bachelor lions, for example, that seem to indicate a preference for animals under 100 kg.

- There is a known bias towards juvenile prey across a diverse array of terrestrial predators *even correcting for prey size*. In other words, there is a known preference for the juveniles of large animals over the adults of smaller ones. So the issue isn’t just size ratios - juveniles are naive and make mistakes. They’re often less athletic than adults. They’re simply easier to hunt, even ignoring size.

- As Tristan laid out very well, there’s a lot of populations dynamics involved - you eat what’s available. What we know of the Mesozoic ecosystems suggests that there should have been a *lot* of juvenile dinosaurs around much of the time. And as was also noted in that post, there can be hard-to-detect predator specializations.

- As difficult as it is to detect predator specializations to specific prey among macro carnivores, I do note that theropods, for the most part, don’t really seem to have the sorts of anatomical traits we might expect in something specialized to hunting proportionally very large animals (aka, they’re not built like cats).

- Lastly, an additional issue we have to keep in mind when trying to interpret the limited direct evidence that we have (such as healed bite wounds) is that young predators are also naive - and they make mistakes. There is quite a bit of mortality and morbidity among living predators from failed attempts to take on animals that are too big/armored/etc. Yearling lions get wrecked by porcupines with some frequency, for example. We even see this with other forms of aggression that are not strictly predation - young crows will sometimes try to mob falcons or Accipiter, and pay the price. It takes time for them to learn which hawks are “safe” to mob.

Cheers,

—Mike H.

[Andreas Johansson]

What would ”built like cats” mean for, say, a tyrannosaur or allosauroid?

This discussion may benefit from more quantification. There’s a lot of room between ”smaller than T. rex” and the 500 kg cited in the original post. 

—
Andreas Johansson

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[Hieu Nguyen]

Thank you Michael - it's interesting to know that at least some male lions may prefer smaller prey. Can you link the study if possible? From what I read seen on male lions, such as Radloff and du Toit, 2004, it seems like they frequently take down adult buffalos, and Dave noted them as an exception in the Reddit discussion shown above (in which I was not involved). 

And just in case that I was unclear - I do not think that Dave's conclusions on theropod prey choice are incorrect. My main question has always been whether modern ecological trends for large terrestrial carnivores support his claim (as he frequently writes). At the moment, I think the data seems rather mixed, slightly favoring a preference towards proportionally larger prey? 

I think it is possibly true that big cats (or at least lions and tigers) may be the exception in their ability to take down larger prey. However, I wonder if prey choice data for animals like spotted hyenas and Komodo dragons (often used as tyrannosaur and carcharodontosaurid analogs) support Hone's idea that large theropods would have targeted significantly smaller prey? From what I know, neither spotted hyenas or Komodo dragons target substantially smaller animals a large majority of the time. 

[Michael Willis]

If you re-read my response Hieu, you'll notice I addressed this point specifically for V. komodoensis. If you'd like detailed reading on this for that species I can send you some literature through. 

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[Hieu Nguyen]

Yes I have seen that, and would appreciate further literature, thank you. Anything by Auffenberg wouldn't be needed though, as I have access to quite a lot of his work. I was trying to ask if it was true that from what you sent and other work I've read, common analogs for large theropods don't seem restricted to substantially smaller animals either. This subject is very much something I need to know more about so I'm trying to not sound argumentative. 

[Gregory Paul]

An advantage of hunting big prey is that once done, it cuts down on the workload in terms of how often a predator or a pack has to go out and get lunch. A big carcass could keep them going for days, allowing lots of R&R in between. 

Another factor may be psychological. Predators get off on hunting, and they may want to fulfill their prowess by taking on the big prey boys and girls on occasion. Biology is not a precise system, mental actions runs on imprecise impulses that hopefully balance out in the end. 

GSPaul

https://groups.google.com/d/msgid/DinosaurMailingGroup/d9d8e794-daab-4e7e-8fcc-2b6e07ac2d7dn%40googlegroups.com

.

[Michael Habib]

> On Dec 23, 2025, at 10:59 PM, Andreas Johansson <andr...@gmail.com> wrote:
>
> What would ”built like cats” mean for, say, a tyrannosaur or allosauroid?

Broadly speaking, higher mechanical tolerance for impacts (either with the ground or other animals). Cats are flexible, high-toughness grapplers with well-above average capacity for soaking impact energy. To the extent that cheetahs can hit drought-baked ground at freeway speeds and just shake it off. Similarly, lions can get run over by adult ungulates and walk it off (yes, sometimes they get wrecked, but most animals would be a smear 100% of the time). Now, raptorial birds are not fragile, and I don’t think theropods were necessarily, either, but they can’t get trampled like a cat or hit the ground at 25 m/s and shake it off. And, of course, size matters here - things like falls become exponentially more problematic for big animals. This matters in the context of the thread, because one of the most obvious risks of trying to tackle an animal 1:1 size ratio (or even greater) is getting knocked over.

Cheers,

—Mike H.

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[Tim Williams]

Jumping off from what Mike said... One obvious difference between felids and theropods is that in felids the forelimbs are an essential part of predation, whereas this is debatable for theropods (including allosauroids).  For felids that specialize in bringing down large prey, the forelimbs are adapted for subduing large prey while the jaws are positioned for the killing bite (Meachen-Samuels & Van Valkenburgh, 2009; DOI: 10.1002/jmor.10712).  

Also, in felids the forelimbs have a dual use in locomotion and prey capture - another key difference from theropods.  (I also include volant theropods in that category, since it's highly unlikely that archaeopterygids and microraptorines used their wings to catch prey.)

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[Andreas Johansson]

Thanks :)

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Andreas Johansson

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[Hieu Nguyen]

Just in case, I don't think I implied at any point that large theropods were as capable of subduing proportionately larger animals as big cats (even though I am not 100% sure just how much more well-adapted big cats are than other carnivores, if someone can cite some studies it'd be great). However, I don't think that animals such as hyenas and Komodo dragons are restricted to substantially smaller prey "a large majority of the time" either? 

[Richard W. Travsky]

Is the assumption here that these large theropods are hunting singly, or in a group/pack (i.e., two or more)? References to wolves or lions would imply comparing with a group. Youtube has videos of lions taking on large prey, like this BBC video of lions taking on an elephant

 

https://www.youtube.com/watch?v=x4nG4JsAyKY

 

Komodos also hunt large prey. They're supposed to be largely solitary but do get together ton hunt. Two komodos against a buffalo

 

https://www.youtube.com/shorts/ky3iPPoYSRQ

 

These seems opportunistic, not really cooperation. Perhaps also with some theropods and large prey?

 

From: dinosaurma...@googlegroups.com <dinosaurma...@googlegroups.com> On Behalf Of Skye McDavid
Sent: Monday, December 22, 2025 9:03 AM
To: DinosaurMa...@googlegroups.com
Subject: Re: [DMG] Juvenile prey preference in large theropods

 

I'm not Dave, but I have discussed this with him on many occasions and we generally agree, so here's my take:

 

Megafaunal herbivores are very big, so if you are a large terrestrial predator that likes to take on prey similar in size to yourself, juveniles of these megafaunal herbivores may be the best targets.

 

In the case of extant large endothermic terrestrial carnivores (e.g. Pantherines, wolves) they do preferentially hunt juveniles, often because the adults of those species are considerably larger than the predators. Lions do preferentially target juvenile zebra, and wolves do preferentially target juvenile moose. 

 

Even for a tyrannosaur, an adult hadrosaur may have been dauntingly large, much as adult moose are for wolves. 

 

So modern predator-prey dynamics absolutely support this hypothesis.

 

Skye McDavid
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On Mon, Dec 22, 2025, 10:45 AM Hieu Nguyen <hieu.ng...@gmail.com> wrote:

In paleontological literature, usually by Dave Hone, I have often seen his hypothesis that large theropods, even tyrannosaurs and carcharodontosaurs, would have mostly targeted juvenile animals (~500kg in weight, based on Hone's Tyrannosaur Chronicles). Before I ask my question regarding this hypothesis, I want to make clear that I am trying to argue or disagree with the main conclusions reached by Hone and Rauhut, 2009. 

 

A point that Hone frequently brings up in both online discussions/talks and books is that modern predator-prey patterns support his hypothesis, that the vast majority of predators take significantly smaller prey. However, based on studies on large, endothermic terrestrial predators (which I think are most analogous to large theropods), there seems to be overwhelming evidence that they prefer prey close to their own size. Even some literature cited by Hone in support of his hypothesis (Energetic constraints on the diet of terrestrial carnivores by Carbone et. al., 1999 for example) notices that larger terrestrial predators prefer prey nearly their own size. With this in mind, is it inaccurate to say that modern predator-prey patterns support Hone's hypothesis, as he often states? 

.

[Hieu Nguyen]

Since the exact social behavior of large theropods is unknown, I don’t think that is considered in this thread. And we know for a fact that predators that live in social groups (lions, spotted hyenas,…) can and do hunt large prey by themselves, proven by both video evidence and studies. The frequency of such hunts likely depends on the species and population. 

[Tristan Stock]

Even if big theropods were social, it likely doesn't change what they're primarily targeting. Extant pack-hunting carnivores don't shift preferences towards larger and more dangerous prey animals in a pack, and most are perfectly capable of catching and killing the same prey species without assistance. Single lions have been reported taking down very dangerous game like giraffe and Cape buffalo, and tigers are purely solitary hunters yet they take prey in the same size range as lions, including targets up to rhinos and young elephant. Snow leopards (50kg in large toms) have even been reported killing adult Bactrian camels (>400kg) by themselves, which is well above even the more extreme examples of pack-hunting lion/large prey size ratios.

When you look at other non-cat social carnivores you see similar trends. Grey wolf packs overly rely on the oldest male to hunt large prey like moose (which they can do even solo with success rates of 49-74% in older individuals), and if the lead male dies the rest of the pack will immediately shift to prey like roe deer, but if the lead female or secondary males all die they will still target moose since they only really need the large male to do most of the hard work. Harris hawks target prey similar in size to other accipitrines, and not all Harris hawk populations even hunt and live in family groups (the behavior is limited to populations in harsh open desert environments, but those outside deserts act like other raptors). Most orca pods target prey much smaller than themselves, and even baleen whale-hunting transients rely a lot on large males to do most of the ramming and drowning of calves.

Komodo dragons are socially complex animals with a lot of ritualized behaviors between individuals, but most experts agree that multiple individuals engaging in predation events are examples of mobbing, and that it doesn't really change much as Komodos target the same types of ungulates regardless of the other individuals around. The video shared is pretty clearly several individuals mobbing a newborn water buffalo that's still trying to stand up (can see the afterbirth coming from the mother as well as on the ground), but they are trying to be the first one to grab the baby, not cooperating. There are reports of cooperative hunting in crocodilians (Dinets (2014)) so these behaviors bracket theropods either way, but even when cooperating crocodilians target fish and feral ungulates, which they would normally take otherwise. They do not suddenly shift to hunting very large ungulates or elephants when cooperating.

Back to the topic at hand, I think the main takeaway from everyone’s comments is that yes large theropods are probably preferentially selecting for juveniles, since that’s just a common trend among carnivores in general. I also think that Habib’s comment on big cats being over-engineered to take on large prey is probably onto something. However, I do have to wonder if that might be less of a cat-specific thing and more of a general carnivoran thing, as canids and mustelids are both known to regularly target very large prey orders of magnitude larger than themselves. Adult megatheropods are normally around the same dimensions of the largest non-sauropod herbivores in their ecosystems, while those dimensions are almost never seen in carnivorous mammals. Perhaps carnivorans are just better at hunting large prey at smaller body sizes, while theropods have a drive to actually get huge and of comparable sizes to their prey to better target them. Would love to see more work examining this.

- Tristan

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[Hieu Nguyen]

A bit unrelated but the bit about a snow leopard killing a Bactrian camel is very interesting - I knew they could kill large prey but that seems like an exceptional case! 

And I have no doubt that it is at the very least possible that theropods preferred juvenile - my main question was that if that is reflected in modern large carnivores. The second point that Hone emphasizes on was that cases of large theropod attacking same sized herbivores (T. rex on Triceratops is his example) would be very rare - "once in a lifetime" kinda of occurrences. I'm not sure if modern large terrestrial predators tackle equally sized prey so infrequently? 

Also should we perhaps make a distinction between the frequency of adult/juvenile animals in predators diet vs. preference? While frequency may reflect preference, in some cases perhaps juvenile prey would not be an option and predators that would have preferred juveniles could have been forced to attack adult individuals? 

[Hieu Nguyen]

Perhaps this would make the question simpler: Would instances of large theropods killing proportionately large prey have been so rare *if* patterns by modern large terrestrial predators are the same?