Laughable and ridiculous statements

[Supercommunist]

Not really too ridiculous but I do think this idea David Hone proposed is silly:

Daivd hone in a blog asserted that he thinks that giant theropods like tyrannosaurus predominatetly hunted juvenile/sub adults animals and that a theropod hunting a full grown adult animal would have been a once in a lifetime opporunity:

Giant theropods probably took juvenile prey for preference over adults, and healthy adults would have been generally avoided.

Tyrannosaurs would face off with a Triceratops bull in a fantastic one-on-one combat the like of which films are based on, but it would be a once in a lifetime experience for at least one on them, and that’s why a T.rex would avoid the possibility and simply snap up something a fraction of the size and lacking the horns and spikes and most importantly, nous, to know better.

archosaurmusings.wordpress.com/2009/08/04/baby-killers-hunting-and-feeding-behaviours-of-large-theropods/

This blog was written in 2009 so I thought it was a forgiveable blunder but in a 2017 youtube video it seems he still beleives this idea.



46:40

I honestly cannot comprehend how a foremost expert could ever come to that conclusion. I don't know of any animal whose diet consists primarily on young animals, barring very specifically adapted animals like egg-eating snakes. I mean, we all heard and know that predators prefer sick/injured/young prey, but that doesn't mean a predator can rely on surviving on those animals, because its not like every herd of animals is going to have a cripple at the back and eventually the young will grow up. We have plenty of modern day examples of predators attacking fully grown and formidable animals.

To be fair, dinosaurs do produce much more offspring than modern day mammals but I still don't think this idea holds up. Due to the fact that dinosaurs come out of eggs, young dinosaurs tend to be way smaller than their parents compared to mammals. A new born elephant for instance is about as big as a person whereas a new born t-rex was as big as a chicken at best. This means that a young edmontsaurus or triceratops would probably be vunerable to coyote sized animals and most of its siblings will have already been eaten by the it has become big enough to actually be a worthwhile meal for a multi ton predator like tyrannosaurus.

If theropds really did mainly feed off juveniles why even get so big in the first place?

[theropod]

Well, it’s a bit of a hyperbolic statement, but I think it’s understandable what he means when he says that an adult Triceratops/T.rex faceoff would be a once in a lifetime experience for at least one of them. Obviously that is not strictly speaking true, but if we assume he meant a faceoff to the death, such as a successful hunt, then it is.

I know of and have discussed with other people in the field who have similar views. While I don’t completely agree, I understand their reasons. As you note yourself, there is a massive difference in reproductive biology between dinosaurs and mammals. In effect, one species of dinosaur, at least the large ones, would fill the analogue ecological niches of several species of mammal during its lifetime, and spend a lot of its life that way. So in any population juveniles (and juvenile biomass) would be abundant, and the pressure for predators to rely on healthy adults (or adult-sized individuals) would be minimal compared to modern ecosystems. But that is not exactly how ecological specializations work. Every predator would be out to get those juveniles, after all. With a certain level of competition it would end up being advantageous to specialize into taking larger prey, just like there are certainly enough small prey species around today that lions could have specialized on, but they didn’t while other predators did. A significant minority of prey individuals effectively free from predation sounds like a buffet that nobody is eating, so as long as it is possible (the only herbivores effectively free of any predation pressure tend to be the ones so large due to ecological/nutritional reasons that it is physically impossible for predators to take them, i.e. large whales, elephants, adults of giant sauropods), something will likely try to eat from the buffet.

Of course there is also some direct evidence for conflict between what were likely adults or at least sizeable individuals of Theropods and their prey (T. rex and Triceratops, Allosaurus and Stegosaurus), but they don’t really allow us to quantify how common such behaviours were. And with abundance of theropod paleopathology I wonder if by comparing the occurrence of pathology between extant large-prey and small-prey-specialists one might be able to draw some inferences. Or maybe someone already tried doing that and I’ve just forgotten about it…

Large theropods do have the predatory adaptations to take on large prey by modern standards. They would appear rather over-built for exclusively targeting small prey, and adaptations this costly don’t usually evolve for "one in a lifetime"-events. If these morphologies did not evolve to tackle large prey, then the all-time go-to sexual display/intraspecific competition would be the only explanation, but then I would expect to at least see more cases of such adaptations discernably being geared towards non-lethal/ritualized competition or display rather than killing, which does not seem to be the case, at least outside Ceratosauria.
But then again, there are extant predators that have predatory adaptations that would suggest extensive specialization for large prey, and for whom "large prey" still tends to equal something way smaller than themselves the vast majority of the time (e.g. some orca ecotypes, great white sharks…).

So just sayig, Hone is far from alone in that opinion, and there is certainly some truth in there whether one whole-heartedly agrees or not.

[creature386]

Seems like another scientific questions that's difficult to answer without a quantifier. That being said though, there are certainly lots of carivores whose preferred prey mass is close to their own or smaller (see our Carnivore prey selection overview thread). If we are talking about sauropod hunters, then "close to their own size" would indeed primarily mean juveniles.

The case with T. rex vs Triceratops is a bit harder. Taken at face value, the "once in a lifetime" claim is likely wrong. However, it's possible that he was talking about movie-like confrontations where mutual injury was more-or-less guaranteed (I'm not sure if taking an injured adult by ambush would qualify as "fantastic" one-on-one combat). Or, like theropod suggested, he might have been more figurative/hyperbolic with the "once in a lifetime" part.

Either way, the statement is probably too ambiguous for this thread. I wonder where we could discuss it. The prey selection thread (admittedly, that one has been, until now, mostly about posting data)?

[Infinity Blade]

But then again, there are extant predators that have predatory adaptations that would suggest extensive specialization for large prey, and for whom "large prey" still tends to equal something way smaller than themselves the vast majority of the time (e.g. some orca ecotypes, great white sharks…).

I feel that these two particular examples you listed are inappropriate comparisons, considering orcas and great whites are aquatic predators that live off of aquatic resources. Since the lion's share of the Earth's surface is covered by water, there's probably a helluva lot more biomass for predators to live off of, especially if they and their prey are living in the oceans. Maybe orcas and sharks can energetically afford to mostly live off of prey much smaller than themselves most of the time.

Also, there are actual differences in the cranial and dental morphology between orca ecotypes. I posted a study before that shows that mammal-eating ecotypes (e.g. transients) have more robust crania than the piscivorous resident and offshore orcas that eat smaller prey. There was also a picture I posted comparing the teeth of transient, resident, and offshore orcas; mammal-eating transients, it turns out, have much thicker and more robust teeth. Piscivorous/small prey specialist orca ecotypes mostly, if not solely, eat prey vastly smaller than themselves because, on a functional level, they might actually not be very well suited for taking on large prey.



R.E. my own personal opinion on the "once in a lifetime" statement: if we're talking about "guaranteed-mutual-injury"-type death battles, I don't know how common those would be, considering I have no idea how commonly the average individual macropredator today gets into these. That is to say, for example, I don't know how many times lions get into fights to the death with cape buffalo, giraffes, etc. that actually want to kill them. If I had to guess, though, I'd say they might come across more than literally one that actually wants them dead in their lifetime.

This brings me to another point. I think one of the reasons (certainly not the only) even large dangerous prey lose their lives to predators (e.g. large wild cattle, or even megaherbivores >1,000 kg, felled by big cats) is because their goal isn't necessarily to kill the predator, whereas the predator's goal is, of course, always to kill the prey item. For prey items, just putting enough distance between themselves and the predator or fending the predator off is usually enough. It can certainly choose to permanently put an end to its assailant, but it's not 100% necessary for the prey item to get what it wants out of the situation (i.e. to simply be left alone). So if Hone is just talking about targeting large prey in general, then his statement is almost certainly hyperbole. Okay, fine, it's not really a death battle, but who cares? I'm willing to bet the same holds true for many modern cases of brontophagy as well.

EDIT: I also want to add that I find Supercommunist's last point interesting. I'd like to add that small(er) predators that would get a good meal out of hatchling or juvenile dinosaurs would, presumably, be a lot more common than big adult carnivorous theropods in any given ecosystem. That would probably solidify the idea that more hatchling and juvenile dinosaurs will probably be killed and eaten by such predators than the big theropods.

[Supercommunist]

Well, it’s a bit of a hyperbolic statement, but I think it’s understandable what he means when he says that an adult Triceratops/T.rex faceoff would be a once in a lifetime experience for at least one of them. Obviously that is not strictly speaking true, but if we assume he meant a faceoff to the death, such as a successful hunt, then it is.

I mean, yeah I would agree that predators don't usually meet larger dangerous herbivores on equal turns and will usually pull a tactical retreat when the herbivore does turn to face them but in his 2009 blog he flat out states he thinks predatory theropods avoided adults, which just seems totally wrong to me.

I feel that even a lot of experts take the "predators prefer easy prey" way too far. Yeah they do prefer it and will pursue it whenever possible, but easy meals don't just fall into an animal's lap. Most of the time, lions, hyenas, and other macro predators just have to suck it up and attack a healthy adult animal when freebies aren't available.

So in any population juveniles (and juvenile biomass) would be abundant, and the pressure for predators to rely on healthy adults (or adult-sized individuals) would be minimal compared to modern ecosystems. But that is not exactly how ecological specializations work. Every predator would be out to get those juveniles, after all. With a certain level of competition it would end up being advantageous to specialize into taking larger prey, just like there are certainly enough small prey species around today that lions could have specialized on, but they didn’t while other predators did.

I have a two main problems with this idea that dinosaurs could exploit juvenile biomass significantly more readily than extant animals. One, new born hatchlings from large clutches have a high mortality rate

Average clutch size for C. porosus in Australia is around 50 eggs (range 2–78; 65.4 to 147.0 g eggs) producing hatchlings from 41.4 to 93.6 g [36] [37]. In the wild an estimated 54% of hatchlings survive to 1-year-of-age

www.ncbi.nlm.nih.gov/pmc/articles/PMC4069027/

Dinosaurs grow a lot faster than crocodiles so maybe their very early development attrition rate it noticeably lower but they'd still have to go through gauntlets like this:



Meso predators and opportunist pterosaurs probably killed a lot of hatchlings and as crocodiles show, not even diligent mothers can save more than half their brood.

The other issue I have with this idea that theropods relied more on sub adults than extant animals is, if fully mature dinosaurs are outnumbered by juveniles and sub adults the same would apply to theropods, meaning, adult would have to not only compete with other smaller predators for these easier meals but younger individuals from their own species as well, which again, I don't think is ecologically tenable.

But then again, there are extant predators that have predatory adaptations that would suggest extensive specialization for large prey, and for whom "large prey" still tends to equal something way smaller than themselves the vast majority of the time (e.g. some orca ecotypes, great white sharks…).

I forgot to clarify that I was mainly speaking about terrestrial animals. Yeah its clear that aquatic predators can survive off of much smaller prey, gharials and such are good examples of that but even than aquatic predators like saltwater crocodiles will opportunistically kill adult buffalo, which apparently makes a significant part of their diet. Even the less pscivore specalized crocodilians are fairly good at catching fish and their ecothermic diet means they only need 10 percent of what an endotherm would need, yet you don't see them avoiding adult prey items. A few days ago, I think Blade posted a study about the thylacine that mentioned that terrestrial predators above 20 kgs predominatetly hunt animals close to their own size or larger, I don't see how a multi ton predator would be able to skirt that rule.

I can't help but feel this idea is a few steps above the tyrannosaurus was an obligate scavenger idea. Yeah, a t-rex would happily eat a carcass or a relatively vunerable young animal whenever possible, but smaller, faster predators probably took most of these easy meals, forcing them to tackle large prey most of the time.

This brings me to another point. I think one of the reasons (certainly not the only) even large dangerous prey lose their lives to predators (e.g. large wild cattle, or even megaherbivores >1,000 kg, felled by big cats) is because their goal isn't necessarily to kill the predator, whereas the predator's goal is, of course, always to kill the prey item. For prey items, just putting enough distance between themselves and the predator or fending the predator off is usually enough. It can certainly choose to permanently put an end to its assailant, but it's not 100% necessary for the prey item to get what it wants out of the situation (i.e. to simply be left alone). So if Hone is just talking about targeting large prey in general, then his statement is almost certainly hyperbole. Okay, fine, it's not really a death battle, but who cares? I'm willing to bet the same holds true for many modern cases of brontophagy as well.

Yeah this was a frustrating to debate this in the AVA forums where people would favor predators over herbivores because occasionally an eland too preoccupied with trying to flee rather than fight was brought down by a leopard. I find that large herbivores often shoot themselves in the foot by being too passive:



^This vid if a pretty good example. A cougar get badly battered by a guanco that was simply trying to dislodge itself. You could say that video would support Hone's claim that predators didn't often kill adults, but I don't think it does. The video does prove that its generally not a good idea to attack a much larger herbivore outside their ususal prey range, for example a t-rex sized theropod attacking a Shantungosaurus, but that video also demonstrates that predators can be ambitious and due to the fact herbivores have a tendency to panick, can be suprisingly succesful when attacking large dangerous animals.

I view tyrannosaurus vs triceratops the same way I view big cat vs boar. Tyrannosaurus probably did somewhat frequently hunt triceratops but did so through ambush and if the assault didn't go to plan would have instantly disengaged. Sometimes, a tyrannosaurus would be gored to death, but even in a hypothetical head on fight the tyrannosaurus probably would have won. I mean even in the fossil record we see theropods attacking pretty dangerous prey. THe velociraptor that presumably botched an ambush while attacking a protoceratops and Montana's dueling dinosaurs.

[Infinity Blade]

Dinosaurs grow a lot faster than crocodiles so maybe their very early development attrition rate it noticeably lower

Actually, a study on Maiasaura showed that the mortality rate during the first year of life was ≥89.9%, a lot worse than the mortality rate for saltwater crocodiles during their first year.

Based on the complete absence of LAGs, 31 tibiae within the sample set represent individuals less than one year of age. Thus, Maiasaura young of the year mortality rate is high (≥89.9%). After the first year, mortality rate sharply decreases (Fig. 6). There is a brief increase in mortality rate between years 2 and 3. By dividing the non juvenile (i.e., 2 or more years of age) Maiasaura into two age groups, the mortality rates of those age groups can be compared. The non juvenile age groupings with the greatest difference in mortality rates (and smallest 95% confidence interval) are 2–8 years old (mean annual mortality rate 12.7%) compared with 9–15 years old (mean annual mortality rate 44.4%), indicating that a second period of elevated mortality begins between 8 and 9 years of age.

Woodward et al. (2015)-> (I downloaded the full paper from Google Scholar)

So a lot of eggs may have been laid, but very few of those would have lived to see their first birthday. It's true that the mortality rate dropped drastically if the remainder survived their second year, but by the third year they already weighed more than a tonne (as said by the abstract).

So yeah, I have to agree with you.

[sharkboy101]

GodzillaLagoon: Megalodon even isn't in top 10 list of apex marine predators. It was very slow and equipped with ineffective teeth. Mosasaurs coexisted with large plesiosaurs that are much more dangerous prey than harmless whales. Not to mention that O.megalodon's principal sources of prey were 4-meter long Cetotheriums.


Great white sharks are feeding mostly on young seals and small fish, they are swallowing whole thing, not mosas.


Leviatan had smaller jaw open range than both Pliosaurus and Mosasaurus and the length of jaws don't have great role.


Bite force is not a point when you have ineffective teeth. Aligators, for example have stronger bite than crocodile monitor lizard, but crocodile monitor with razor sharp teeth can deal much more serious damage.


Nope, they can't. Whale sharks could be easily hunted down with harpoon, but for hunting crocodile you would need much more serious weapons. Sharks just have primitive neural system which allows them not to die from pain.

www.deviantart.com/wdghk/art/Biggest-Predators-853706039?comment=1%3A853706039%3A4870105099

[kekistani]

Sept 17, 2020 6:30:12 GMT 5 sharkboy101 said:

GodzillaLagoon: Megalodon even isn't in top 10 list of apex marine predators. It was very slow and equipped with ineffective teeth. Mosasaurs coexisted with large plesiosaurs that are much more dangerous prey than harmless whales. Not to mention that O.megalodon's principal sources of prey were 4-meter long Cetotheriums.


Great white sharks are feeding mostly on young seals and small fish, they are swallowing whole thing, not mosas.


Leviatan had smaller jaw open range than both Pliosaurus and Mosasaurus and the length of jaws don't have great role.


Bite force is not a point when you have ineffective teeth. Aligators, for example have stronger bite than crocodile monitor lizard, but crocodile monitor with razor sharp teeth can deal much more serious damage.


Nope, they can't. Whale sharks could be easily hunted down with harpoon, but for hunting crocodile you would need much more serious weapons. Sharks just have primitive neural system which allows them not to die from pain.

www.deviantart.com/wdghk/art/Biggest-Predators-853706039?comment=1%3A853706039%3A4870105099

Ah yes, the 2 largest macropredators EVER are below a creature that weighs 1/6th as much as them/

[kekistani]

about half this card is made up of them

[Infinity Blade]

"Shastasaurus CAN into ramming"

Lol wut? What is this grammar?

Balaenoptera sp. like the blue whale are well built to swim quickly from their predators (particularly orcas), but they do shockingly very little to nothing to actually physically fight them off, even when they're being attacked.

Bigger animals do tend to be slower, particularly when we're talking about gigantic terrestrial animals (which are a special context, anyway). The probable exceptions being when the smaller gigantic animal is a highly graviportal one (e.g. a sauropod, stegosaur, elephant, etc.) compared to one that at least retains adaptations for cursorial running (e.g. a rhino, theropod, ceratopsid, ornithopod, etc.).

[kekistani]

Oct 4, 2020 6:40:42 GMT 5 Infinity Blade said:

"Shastasaurus CAN into ramming"

Lol wut? What is this grammar?

Balaenoptera sp. like the blue whale are well built to swim quickly from their predators (particularly orcas), but they do shockingly very little to nothing to actually physically fight them off, even when they're being attacked.

Bigger animals do tend to be slower, particularly when we're talking about gigantic terrestrial animals (which are a special context, anyway). The probable exceptions being when the smaller gigantic animal is a highly graviportal one (e.g. a sauropod, stegosaur, elephant, etc.) compared to one that at least retains adaptations for cursorial running (e.g. a rhino, theropod, ceratopsid, ornithopod, etc.).

1. Grammar is purposefully bad-it's a parody of the worldball "Poland CAN into space" meme and doubles as typical denis-style grammar.

2. The Blue Whale kills Megalodon by tailslapping and ramming it to death, according to Denis.

3. Oh yeah, but Megalodon is slow because it is huge according to Denis, but even though it is smaller than Livyatan (says him) Livyatan is faster. Generally the rule that bigger=slower is true but Denis will make exceptions to that rule specifically if he prefers one animal over another.

[Infinity Blade]

I know the grammar was deliberately bad, I was just incredulous that even denis could/would say something like that.

Oh yeah, but Megalodon is slow because it is huge according to Denis, but even though it is smaller than Livyatan (says him) Livyatan is faster. Generally the rule that bigger=slower is true but Denis will make exceptions to that rule specifically if he prefers one animal over another.

Ah, okay.

Oh denis.

[sharkboy101]

Wouldn’t surprise me if Denis is having the same arguments on DA and Quora. And I think he deleted his who would win series on his wattpad account.

[kekistani]

Oct 4, 2020 9:03:58 GMT 5 Infinity Blade said:

I know the grammar was deliberately bad, I was just incredulous that even denis could/would say something like that.

Oh yeah, but Megalodon is slow because it is huge according to Denis, but even though it is smaller than Livyatan (says him) Livyatan is faster. Generally the rule that bigger=slower is true but Denis will make exceptions to that rule specifically if he prefers one animal over another.

Ah, okay.

Oh denis.

How about "We gotta y'all about portion" for bad grammar? Actual sentence from the Carnivora Meg vs Livyatan thread. If you're wondering he was trying to say "We have to remember proportions"...I think.

[kekistani]

Oct 4, 2020 9:23:22 GMT 5 sharkboy101 said:

Wouldn’t surprise me if Denis is having the same arguments on DA and Quora. And I think he deleted his who would win series on his wattpad account.

Lmao he did

and yes he is