Megalodon vs. Livyatan melvillei

[theropod]

Oct 12, 2019 1:58:50 GMT 5 Grey said:

Oct 12, 2019 0:48:11 GMT 5 theropod said:

Which authors? Where did they publish it? What evidence did they cite identifying C. megalodon as the culprit?

Check the paper by Godfrey, they simply consider meg to be the most likely reasons compared to the others.

What paper? That’s why I’m asking

EDIT: I assume it’s this one www.vmnh.net/content/uploads/PDF/Research_and_Collections/Jeffersoniana_Number_16.pdf

[theropod]

…So in other words, no evidence?
In fact, not even considering a possible collision with a physeteroid (of unknown size), which would be equally possible. And of course, published several years before many relevant taxa of stem-physeteroids were even described (including Livyatan), so they couldn’t really have considered them had they wanted to, although of course as we know now, stem-physeteroids were essentially globally distributed during the Miocene, and likely to have been just as present in the same fauna.

I think we need to be clear on what we consider an argument here, or evidence.

In this case, a specimen that could have plausibly been rammed by either, something else entirely, or not at all, is being misconstrued into an argument for ramming, specifically on the part of the shark.
Moreover, even though it is a vastly smaller animal estimated at 6 m, and on top of that survived the collision, it is being misconstrued into an argument that said ram must have been particularly potent, almost on par with the physeteroids’ (close enough for the difference to not really matter)

In the face of evidence that Physeter would be able to kill a similar-sized animal with a ram without injuring itself, and ample anatomical evidence that Livyatan, and other odontocetes in general, would be much more suited

The first part is a matter of specificity of the argument, and your interpretation seems to be more based in belief than actual data, and the second part at the very least is a deliberate misrepresentation of the evidence to suggest a conclusion it doesn’t actually support.

As to why a 6 m cetacean isn’t really a good example (even presupposing that this was necessarily ramming by a megalodon), there’s an easy calculation you can do to see why. First off, even if that cetothere was as bulky as a right whale, it would have weighed less than 3 t. If it was more like a grey whale or balaenopterid, more likely 2 t. So let’s be generous and assume that was a 3000 kg whale.
Let’s be even more generous and assume the megalodon in question was 10.5 m long, the lower end of its adult size range (although this figure might be subject to some upwards revision), meaning it would likely mass around 12 t.
How much accelleration (and force) the ramming shark experiences is directly related to how much inertia the object it is ramming has.

And again, the shark’s head just doesn’t have a structure comparable to a melon and spermaceti chamber, or even a stiff and thickened skull, to withstand these kinds of forces if ramming another large animal at high speed.

[sam1]

..yeah, ramming a 7-10 times smaller animal (let's assume a 13m megalodon rammed a 6m whale), is absolutely nothing worth noting in the sense of true ramming. For one, the collision stress would be next to minor for the shark, and for two, why in the hell would the shark even bother ramming it? Why not just open the mouth instead and chomp the whale in half?!

It's nothing but a ridiculous argument.

[Life]

Oct 11, 2019 4:26:39 GMT 5 theropod said:

In addition, the assumption that a ram by a 30-60 ton whale would be just a sort of minor nuisance that might temporarily deter the shark is frankly wrong.

Even orcas (and reportedly even bottlenose dolphins) use rams to lethal effect, even against larger whales (and sharks), and despite being themselves an order of magnitude smaller than Livyatan. In these taxa, damage seems to be primarily localized, which explains why they don’t require a large dampening spermaceti organ, but a pointed, stiff rostrum. Physeteroids however are a different story.

The ramming adaptations and capabilities of extant Physeter have been studied. At the scales we are talking about, a single ram at reasonably high speed may well end the fight (and not just temporarily) or at least cause major injury, simply by inducing a fatal level of accelleration on even a large-bodied opponent.

Carrier et al. 2002 simulated that under all their assumptions for dampening constants, a Physeter hit by another Physeter at 3m/s (about 11 km/h) would experience g-forces at which fatal injuries would occur, despite only mild accellerations to the attacking whale. Now as I am sure someone will bring up, Livyatan does have a smaller spermaceti organ than Physeter, but it is still seriously sized, I remember the head alone coming out at over 9 t in my model, and that was under very conservative assumptions regarding the size of the cranial soft tissues. The giant size of the spermaceti organ (and junk) in sperm whales is also subject to other pressures than just the one towards ramming, and hence might be overbuilt for this purpose alone.
And we are not requiring the Livyatan to necessarily kill the shark in one single ram or be able to sink a whaling ship of over 200 tons, it is enough to cause serious injuries (not something the shark would just take as a cue to retreat and come back later, something that would be life threatening, at the very least while faced with a large, formidable opponent). Which we can even expect to happen more easily to a shark than another whale, as we also need to consider the local effects the concentration of such forces on a relatively small area (the frontal area of the whale‘s junk) could have against some of the not so well protected parts of the shark (chondocranium, gills, internal organs…).

This is not a mildly unpleasant push that might cause the shark to back off and come back later. We are talking about a kinetic energy at least equivalent to being hit by a bus. Essentially, a battering ram. The physeteroid head has adaptations specifically to withstand and dissipate this energy (Panagiotopoulou et al. 2016). The shark simply does not. A head on collision with a 30-60 ton whale? From what we know, potentially fatal.

It seems periodic reminders of this are needed, as no matter how often the evidence is posted, after a while people revert back to thinking of ramming as some sort of mild annoyance.

This seems to be a one-sided perspective.

Majority of odontocetes including delphinids exhibit ramming behavior for different ends including as a defensive measure.

Even some of the mysticetes are known to exhibit ramming behavior at times; Gray whales and Humpback whales are usual suspects in modern times.

Cetaceans at large, are also known to employ tail slapping technique to defend themselves at times.

Therefore, sharks which are attempting to hunt cetaceans, are likely to experience ramming as well as tail slapping at some point. How many sharks have succumbed to these blows by the way? Any statistical data?

POINT OF CONTENTION

A macropredator which clearly evolved for big-game hunting, must have necessary biological adaptations to cope with affiliated risks and/or pressures, or it will not be up to the task.

Megalodon did not had a purposeless existence; it had a profound impact on ecosystems of its time. Megalodon was the greatest natural agent to ensure checks and balances on the populations of cetaceans across the board including in the case of Livyatan.

So what kind of biological adaptations would be necessary to enable big-game hunting for sharks in marine environments? Some of these are listed below:

- Gigantism (Wroe et al., 2008);
- Excellent killing apparatus (Wroe et al., 2008);
- Regional endothermy (Ferrón, 2017);
- Thickness of cartilage*

MERITS OF CARTILAGE

For starters, cartilage have superior shock-absorbing properties as well as elasticity than solid bones.



Why do you think human knees contain cartilage? Knees are subject to much higher amount of stresses than other parts of the body during physical activities and solid bones are not up to the task, so cartilage enable humans to perform functions and cope with affiliated pressures which they cannot otherwise.

Enlightening study for reference:-

Malekipour, F., & Lee, P. V. (2019). Shock absorbing ability in healthy and damaged cartilage-bone under high-rate compression. Journal of the mechanical behavior of biomedical materials, 90, 388-394.

Key observation is that thickness of cartilage will make substantial difference in terms of coping with extreme forces (Malekipour & Lee, 2019), and therefore an important consideration.

*NOT ALL SHARKS ARE CREATED EQUAL

When WE take a look at fossilized remains of Megalodon, we notice cartilaginous structures that are extremely ROBUST/STRONG on average, or used to be in real life.



Closer look



Megalodon's cartilaginous structures put that of others to shame in all aspects. WE not talking about just a shark here, WE are talking about the shark here.

Megalodon's cartilaginous structures are/were clearly built to cope with extreme levels of stresses as well as be excellent in 'shock-absorbing' capacity. This biological characteristic is in line with adaptations to cope with the stresses of big-game hunting in marine environments.

Megalodon was likely to experience ramming as well as tail slapping from cetaceans on a frequent basis, and it had to be strong enough to endure these blows when they came. This shark should be able to take a lot of punishment in its trophic interactions because it doesn't have the luxury to slip away from a situation on a moment's notice; this shark is/was a multitonned macropredator (in the higher end of the spectrum) after all.

Unfortunately, little attention is paid to biomechanical considerations for Megalodon, how it was coping with competitive pressures in various environments, and what kind of competitive pressures it was subjecting other lifeforms to in turn. WE need studies like Wroe et al (2008), Ferrón (2017) and Gilbert et al (2018) to understand the bigger picture here. Megalodon's biological capabilities and resultant 'competitive game' can be far better understood from biomechanical considerations and viewpoints.

Much of the focus is directed towards pointless discussions about when Megalodon became extinct and which animals were 'supposedly' responsible. Talk about misplaced priorities and being excessively dumb. And I am rather worried that people are being awarded PhDs for this kind of stupidity.

FORCES IN QUESTION

Given Megalodon's physiology, it would require something substantially impactful to drive it away. However, few would be up to the task, to produce forces of such magnitude. Livyatan melvillei is a notable candidate of-course.

Oct 10, 2019 22:39:23 GMT 5 theropod said:

Life 1) The site that sold this tooth claims it is Physeter sp.

paleodirect.com/wh023-largest-complete-fossil-sperm-whale-tooth-with-megalodon-shark-bites/



It’s not that I particulatly trust them (they also have a rather colorful interpretation on how this happened, "fight with the shark and whale locking jaws"), but the tooth does look similar to Physeter teeth, they provide a figure plate of a Physeter skull and teeth showing this: paleodirect.com/product_images/uploaded_images/odont1.jpg



It could also be a Livyatan tooth, anatomically that would be plausible as well. In that case, the first from the northern hemisphere.



Anyway, what they interpret quite confidently as a megalodon bite mark also seems a bit overinterpreted. Even is it is though, how is that evidence megalodon preyed on this whale? A bite to the jaw would appear a very strange predation technique indeed.



2) Of course. I would presume either one would want to end the fight quickly, but of course the question is if they could, i.e. if their opponent would let them do this. For that reason, of course it would seem exceedingly unlikely they would really fight on equal ground in a natural setting, even one preying on the other with the benefit of ambush would seem rather unlikely due to the risk involved.



4) I am not doubting this. Surely, megalodon was one of the greatest macropredators to have ever lived. As was Livyatan.



5) thanks. Yes, I know the article. As I recall, that is a piece of popular science authored by a journalist, not by Bretton Kent.

1. Physeter sp. = unknown species / undetermined species

"This is a MASSIVE and impressive specimen - the BEST we have ever handled or offered. It is a LARGE, complete tooth from a prehistoric Sperm Whale of the family Physeteridae dating back to the Miocene/ Pliocene Period. Like T. rex, the Sperm Whale ruled the ancient seas and shared the title of "king" with the Megalodon Shark during its day."

Now, take another look:-



That jaw structure belong to a modern-era Physeter macrocephalus, and its teeth are similar to Type D in the photo below.



Relevant details in this link: theworldofanimals.proboards.com/post/47686

The tooth being held in the hands with the intent to compare with others, is similar to Type C in the Livyatan holotype.

The tooth containing cuts from Megalodon (WH023), is also similar to Type C in the Livyatan holotype.



This tooth seems to indicate presence of Livyatan types as far as in the lower North American environments. Although these fossils are rare which is strange.

WH023 = Savannah Basin (Georgia)

Do you find bite marks on this specimen unsettling? 

Intent behind attacking the skull of an animal would be to kill it swiftly. Megalodon was well-equipped to cut through the bones (mechanical advantage of having a robust dentition). Now combine this quality with gigantism, and Megalodon could attack a large cetacean in numerous ways - a luxury that other sharks do not have. However, killing a large cetacean swiftly is a sound predation strategy, and also a meaningful indicator of Megalodon's intelligence and/or learning capacity.

Fossilized remains of an unknown baleen whale, excavated from Sharktooth Hill, also suggest an attack on the skull.



"A fossilized whale was also found at the quarry — missing its head. The owners of Shark Tooth Hill, Sean and Lisa Tohill, have long wondered if the whale was killed by a megalodon."

Link: www.businessinsider.com/scary-truth-about-megaladon-eating-whales-2013-8

This excavation motivated development of a special episode for Shark Week TV series (Sharkzilla) in which dry-skull method was employed to understand what a Megalodon could do to other objects.

Nevertheless, WH023 suggest that large macropredatory sperm whales, or raptorial odontocetes in general, were not immune to predation from Megalodon. This is a significant discovery from which numerous inferences can be drawn which in turn shall advance our understanding of the unforgiving Miocene marine environments.

2. That the Megalodon tore through the skull a large sperm whale (WH023) in a trophic interaction, is a significant pointer towards what could happen to Livyatan in this fight. 

There is much about these two animals which WE do not understand at present, there are aspects of animals which do not fossilize.

It is difficult to determine whether Megalodon were attacking raptorial odontocetes on a regular basis (or not). Although Megalodon's demise seem to coincide with a major drop in the diversity of the Order Physeteriodae by the end of Miocene.

Abstract of an interesting study:-

"Physeteroidea (sperm whales) attained great diversity during the Miocene and early Pliocene, and the phosphatic sands of the U.S. Atlantic Coastal Plain have produced thousands of specimens. Although postcranial and cranial materials are rare, teeth are remarkably common and have the potential to provide valuable insight into the lives of these animals. We examine a suite of Physeteroidea indet. teeth from the Lee Creek Mine to better constrain the life history and ecology of this extinct group. Wear facets indicate that these animals, unlike modern sperm whales, had both maxillary and mandibular teeth, suggesting a raptorial feeding ecology more akin to killer whales. A relationship between tooth diameter and body size established for modern odontocetes suggests that these animals as adults were also about the size of modern killer whales. Because physeteroid teeth grow continuously over ontogeny and are not replaced, counts of accretionary growth layer groups can be used to ascertain the age of an animal at death. Tallies of growth increments from 10 teeth, including some of the largest available, reveal that life spans only rarely exceeded 20 years, significantly shorter than the 65+ years typical of modern sperm whales or orcas. Despite their large size, these odontocetes experienced a ‘fast’ life history, more like beluga whales today. We suggest that the rapid growth and short life span exhibited by the Lee Creek physeteroids are, like the modern beluga, evolutionary responses to high predation pressure imposed by large co-occurring predatory taxa, particularly including Carcharocles megalodon or other large macroraptorial physeteorids.
"

From Gilbert et al (2018); citation below in the REFERENCES section.

Relatively longer lasting members of the Order Physeteriodae were probably already specialized predators of squids and small fish, or slowly changed form (evolved) to hunt squids and small fish in order to better cope with the pressures of Pliocene (cooling trends; geographical shifts; mass extinction events).

3. Nothing in your response so addendum.

4. WE need more insight about Livyatan's dietary preferences and not jump to conclusions on the basis of superficial observations. I notice this bias even in professional circles although many underestimate Megalodon in their estimations which is plainly stupid.

5. Not an issue because Hell's teeth contain valuable insight from professionals, just not articulated like a formal scientific publication (unfortunately), but good enough to refer to when necessary.

--- --- --- ---

REFERENCES

Ferrón, H. G. (2017). Regional endothermy as a trigger for gigantism in some extinct macropredatory sharks. PloS one, 12(9), e0185185.

Gilbert, K. N., Ivany, L. C., & Uhen, M. D. (2018). Living fast and dying young: life history and ecology of a Neogene sperm whale. Journal of Vertebrate Paleontology, 38(2), e1439038.

Wroe, S., Huber, D. R., Lowry, M., McHenry, C., Moreno, K., Clausen, P., ... & Summers, A. P. (2008). Three‐dimensional computer analysis of white shark jaw mechanics: how hard can a great white bite?. Journal of Zoology, 276(4), 336-342.

--- --- --- ---

sam1
Grey
elosha11

[theropod]

Again, please refer to what I (and others) wrote in the mosasaur discussion. This is simply a major over-interpretation of a fossil tooth mark.

You jump to the conclusion not just that there was a trophic interaction (and not, for example, scavenging) but also as to the nature of said interaction (shark preying on whale, and not the reverse) when there is no evidence of either. Not to mention this claim that the shark "tore through the skull of a large Physeteroid", which is also not exactly realistic.

No need to lecture me on the rules of zoological nomenclature, I work in collections management. Physeter sp. means a species in the genus Physeter. Livyatan melvillei is a species in the genus Livyatan. But besides the point, since their taxonomic assignment appears very doubtful, I was just pointing it out. Proper taxonomic assignment for this specimen would likely be Physeteroidea indet.

That a macropredatory shark would have to deal with ramming and tail slapping from its prey is obvious, and of no concern here. It has already been noted that none of these animals are adapted to ramming to a similar degree as Livyatan or Physeter, or as large for that matter. There is a difference of being tail-slapped or rammed by a 6 m cetothere, or being rammed by a 15 m physeteroid. A difference in body mass, and resulting impact force, by an order of magnitude, for one. This analogy is really rather like saying that because I don’t sustain serious injuries from being punched by a toddler, I would also be almost immune to a punch from a heavyweight boxer.

Same goes for attack on the skull. Because an animal can attack the (far less solid, far smaller, and far less dangerous) skull of a cetothere, that doesn’t automatically mean it could do the same with Livyatan. Which is not just very risky due to the aforementioned ramming abilities of the physeteroid, not to mention a very powerful set of jaws and teeth in its own right, but also an extremely bony target to bite (in fact, likely among the biggest and most solid pieces of bone of any vertebrate in earth’s history).

[sam1]

I expected you to mention that the sperm whale teeth image Life used for comparison is terrible.
Here, literally from the first page of google sperm whale teeth search.

images.app.goo.gl/X8qxdRRCMjrnxWvG9

images.app.goo.gl/8bVwuyZL1pNuZHM1A

[Grey]

Oct 12, 2019 11:34:13 GMT 5 sam1 said:

..yeah, ramming a 7-10 times smaller animal (let's assume a 13m megalodon rammed a 6m whale), is absolutely nothing worth noting in the sense of true ramming. For one, the collision stress would be next to minor for the shark, and for two, why in the hell would the shark even bother ramming it? Why not just open the mouth instead and chomp the whale in half?!

It's nothing but a ridiculous argument.

What is ridiculous is considering the shark in question was just a large floating blob unable to do anything against an equivalent sized foe while we have evidence that even small modern sharks are able to land some bites on their multitons predatory orcas.
While I agree on the sheer weaponry of the whale, you still display the same agressive bias while discussing this interesting subject, which makes you act again more like a sport supporter than a science enthusiast, the reason why I'll stop this discussion for now before it goes really ridiculous like at times before.

Theropod, the authors simply consider a collision with a meg the most likely reason, while not denying the others. But meg is the most present predator and the one with the best recorded hint of predation at cetotherid so far of the Chesapeake Bay.

The ramming by a megalodon on its preys is variously described off hand as a car being hit by a freight train but if you persist to say that the shark was a foe unable to doe anything against the allegedly perfect fighting physeteroid, I'd rather prefer that you explain your actual outcome about that match instead of nit-picking at any argument proposed in favor of the shark, which really sounds like to be a poor, albeit large organism, when reading you.

[theropod]

I don’t want to stoop to those levels of making up straw men and insinuating biased intentions once again, and so I won’t comment on that any further. If you want to discuss the science, I am here.

The reality is that this was a vastly smaller whale compared to both Livyatan and megalodon, that we don’t know what rammed it (or whether it was even rammed at all), and it didn’t die from it.
Studies on Physeter suggest that a ramming attack between similar-sized organisms at these scales could be fatal, and that the physeteroid head has adaptations to withstand such impacts. There is no known comparable adaptation in extant sharks, and postulating entirely novel structures in the cranium of megalodon that would allow this is, at the very least, baseless speculation. Hence, we have to expect that if a megalodon was ramming a similar-sized animal with sufficient momentum to cause severe injury, it would just as severely injure itself (if not more, due to ramming with the comparatively vulnerable chondocranium, a cartilaginous structure that is not excessively calcified and would not protect the central nervous system from an impact of such magnitude) as the animal it rammed. The same simply is not true for a physeteroid.
Why must you keep arguing about this, is it so impossible to concede that this is a point where the whale has a clear advantage, just as I and others can concede that there are clear advantages to the shark in some areas (such as gape or cutting ability)?

Could a megalodon ramming a Livyatan potentially cause severe damage? Sure, any object this large could. But could it do that without killing itself? Highly doubtful, and a small cetothere being rammed by an unknown attacker without fatal outcome doesn’t help your case in this regard. Obviously in most situations the shark would be better off simply biting instead, which we should not conflate (we aren’t talking about the Livyatan biting either right now, which of course it could do in addition to ramming). In a head on collision, the outcome is rather clear though.

A freight train weighs thousands of tons and travels at twice the likely top speed of megalodon, the kinetic energy is thus several orders of magnitude larger, so the very fact that you are using this being "variously described off hand" as such as an argument is really unsettling as to the quality of arguments that are being advanced. And yet, if a freight train collides head on with another freight train, I can assure you that the trains will not come out of that collision unscathed. Unlike a Physeter ramming a similar-sized animal.

And again, this being more in response to Life , an effective ram from a physeteroid at these scales would not just "drive off" megalodon, it might well kill it, or at least seriously injure it.

sam1 Well I already brought up the figure plate from the seller’s site and pointed out the tooth resembles those shown there, and that some Physeter teeth look similar. I have not had any luck tracking down where the plate is from and what exactly the teeth are referred to. Clear case of why people have to cite their figures and references properly.
However, what appears to be enamel on the crown is inconsistent with it actually being a Physeter tooth.

My main issue was with this misunderstanding about the implications of trace fossils that Life appears to have. If my explanation (as a paleontologist) is not good enough, fine. But then, maybe at least published interpretations of bite-marked specimens should be taken seriously and not dismissed as bias and idiocy because they conflict with preconceived ideas.

A single, unhealed bite mark is not proof of a trophic interaction between living animals. Period. You can ask any ecologist, palaeoichnologist or vertebrate palaeontologist and they will back me up on this.

[Grey]

The freight train comparison is always reduced to the weight of a railroad car which weighs about the same as the purpoted weight for a megalodon, I really need to precise this...

You then imply that a shark ramming a boat larger than itself will kill itself.

I would agree a ramming would injure the shark snout, but killing itself instantly, not so much.

It still looks like your depiction is of an impotent predator that only has size for itself against other marine megafauna.

[theropod]

You then imply that a shark ramming a boat larger than itself will kill itself.

No I do not. The boat does not have the mechanical properties of another animal, if its hull gives under the impact (depending on the built, not necessarily that difficult) then the impact energy goes into deforming the boat, not the shark. And once again, we are not talking about the scales of a mako or white shark here, we are talking about something way bigger.

Smaller animals can get away with lots of things larger animals would die from. I assume you are familiar with the calculations showing that T. rex would likely fatally injure itself it it tripped, right? Just because I don’t die if I trip, doesn’t mean something 100 times my weight wouldn’t.

I would agree a ramming would injure the shark snout, but killing itself instantly, not so much.

Straw man. I did not say it would be "killing itself instantly" avada kedavra style. I did talk of serious and potentially fatal injury, and I think I’ve described quite well why this would be the case.

The shark’s central nervous system is only protected by the chondocranium in such a scenario (ramming with the snout), with no special adaptations to protect it. That is a bit like Sam’s earlier comparison of a human butting heads with a ram.

Now I think we are all agreed that the shark would not be stupid. Which would mean that it would avoid a style of attack that would carry serious risk to fatally injure itself.

It still looks like your depiction is of an impotent predator that only has size for itself against other marine megafauna.

Again, straw man. Did you notice me make any such claims about you? No? Did I say that anywhere? No? Then please stop making them.

[sam1]

Oct 12, 2019 17:43:06 GMT 5 Grey said:

Oct 12, 2019 11:34:13 GMT 5 sam1 said:

..yeah, ramming a 7-10 times smaller animal (let's assume a 13m megalodon rammed a 6m whale), is absolutely nothing worth noting in the sense of true ramming. For one, the collision stress would be next to minor for the shark, and for two, why in the hell would the shark even bother ramming it? Why not just open the mouth instead and chomp the whale in half?!

It's nothing but a ridiculous argument.

What is ridiculous is considering the shark in question was just a large floating blob unable to do anything against an equivalent sized foe while we have evidence that even small modern sharks are able to land some bites on their multitons predatory orcas.
While I agree on the sheer weaponry of the whale, you still display the same agressive bias while discussing this interesting subject, which makes you act again more like a sport supporter than a science enthusiast, the reason why I'll stop this discussion for now before it goes really ridiculous like at times before.

Theropod, the authors simply consider a collision with a meg the most likely reason, while not denying the others. But meg is the most present predator and the one with the best recorded hint of predation at cetotherid so far of the Chesapeake Bay.

The ramming by a megalodon on its preys is variously described off hand as a car being hit by a freight train but if you persist to say that the shark was a foe unable to doe anything against the allegedly perfect fighting physeteroid, I'd rather prefer that you explain your actual outcome about that match instead of nit-picking at any argument proposed in favor of the shark, which really sounds like to be a poor, albeit large organism, when reading you.

Uh..there is absolutely no "aggressive bias" coming from my part. Neither have I ever stated such opinions on the shark, as you imply. 
I don't think of it as a large floating blob.
I think of megalodon as nature's ultimate straightforward apex predator and the most efficient and potent macropredatory killer to ever grace this planet.
What I have argued for is the undoubtable ramming superiority of the whale. That is literally it, as anyone can check and see.
And if I see a ridiculous argument that serves no purpose (megalodon supposedly ramming a 6m whale) I will call it as such.
Aggressive?
I rhink the irony is on you.

[Life]

Oct 12, 2019 17:11:30 GMT 5 sam1 said:

I expected you to mention that the sperm whale teeth image Life used for comparison is terrible.
Here, literally from the first page of google sperm whale teeth search.

images.app.goo.gl/X8qxdRRCMjrnxWvG9

images.app.goo.gl/8bVwuyZL1pNuZHM1A

Here is a better view.



Closer look at the rows of teeth:



Of-course, there are different types of teeth in the jaw structure of modern-era P. macrocephalus.

However, the Megalodon-bitten tooth (WH023):-

1. Have a very pronounced crown



2. The tip of crown show intense wear-and-tear from feeding activities



3. Was already massive in size (8.25 inches long), and could grow larger (look at the root structure; underdeveloped)



4. Could be positioned in the upper jaw structure, like this:



Dentition of the Livyatan holotype for reference.



WH023 is absolutely similar to Types H and I in that collection.

Connect the dots.

You cannot rule out the possibility of WH023 being a Livyatan specimen.

[Grey]

Again, straw man. Did you notice me make any such claims about you? No? Did I say that anywhere? No? Then please stop making them.

You didn't tell anything like this but the rebuttal of any argument in favor of the shark makes me think I'd rather be interested, since you're a scholar, in your opinion of the actual outcome. I mean it looks like megalodon was an unadapted organism and that sharks are weak. But there are many anecdotal accounts about the durability and domination of sharks over marine communities and megalodon in particular. Physical attributes are not the only reason to meg domination and longevity as an apex predator, but at the end, it seems reading you, even more than sam1 who is openly a cetacean enthusiast, that nothing in the shark was notably impressive to deal with an odontocete its size. Just like denying the possibility of the shark being possibly larger. So I'm interested in your actual opinion but understand that a bias can always occure even in a neutral mind.
That is why I often revise the question under another angle as we discussed often these past months.

[Grey]

Oct 12, 2019 18:58:59 GMT 5 sam1 said:

Oct 12, 2019 17:43:06 GMT 5 Grey said:

What is ridiculous is considering the shark in question was just a large floating blob unable to do anything against an equivalent sized foe while we have evidence that even small modern sharks are able to land some bites on their multitons predatory orcas.
While I agree on the sheer weaponry of the whale, you still display the same agressive bias while discussing this interesting subject, which makes you act again more like a sport supporter than a science enthusiast, the reason why I'll stop this discussion for now before it goes really ridiculous like at times before.

Theropod, the authors simply consider a collision with a meg the most likely reason, while not denying the others. But meg is the most present predator and the one with the best recorded hint of predation at cetotherid so far of the Chesapeake Bay.

The ramming by a megalodon on its preys is variously described off hand as a car being hit by a freight train but if you persist to say that the shark was a foe unable to doe anything against the allegedly perfect fighting physeteroid, I'd rather prefer that you explain your actual outcome about that match instead of nit-picking at any argument proposed in favor of the shark, which really sounds like to be a poor, albeit large organism, when reading you.

Uh..there is absolutely no "aggressive bias" coming from my part. Neither have I ever stated such opinions on the shark, as you imply. 
I don't think of it as a large floating blob.
I think of megalodon as nature's ultimate straightforward apex predator and the most efficient and potent macropredatory killer to ever grace this planet.
What I have argued for is the undoubtable ramming superiority of the whale. That is literally it, as anyone can check and see.
And if I see a ridiculous argument that serves no purpose (megalodon supposedly ramming a 6m whale) I will call it as such.
Aggressive?
I rhink the irony is on you.

Dude, I am not agressive as I've not started calling your arguments ridiculous and I've certainly showed to be able to agree on other's points.
Now that you're saying it, I was about to ask you if you'd consider meg as Nature's most lethal macropredator while Livyatan as the most versatile fighter ?

[theropod]

Oct 12, 2019 19:21:08 GMT 5 Grey said:

Again, straw man. Did you notice me make any such claims about you? No? Did I say that anywhere? No? Then please stop making them.

You didn't tell anything like this but the rebuttal of any argument in favor of the shark makes me think I'd rather be interested, since you're a scholar, in your opinion of the actual outcome. I mean it looks like megalodon was an unadapted organism and that sharks are weak. But there are many anecdotal accounts about the durability and domination of sharks over marine communities and megalodon in particular. Physical attributes are not the only reason to meg domination and longevity as an apex predator, but at the end, it seems reading you, even more than sam1 that is openly a cetacean enthusiast, that nothing in the shark was notably impressive to deal with an odontocete its size. Just like denying the possibility of the shark being possibly larger. So I'm interested in your actual opinion but understand that a bias can always occure even in a neutral mind.
That is why I often revise the question under another angle as we discussed often these past months.

So once again, I ask you to stop making up straw men (a straw man argument means responding to points I never made, e.g.  "megalodon was an unadapted organism and that sharks are weak") and alledging biases, and you respond to that by listing essentially the same strawmen, alledging essentially the same biases once again? That’s just going nowhere.

You know my opinion about the outcome, I have told you numerous times, frequently only on your insistence. Maybe you just cannot understand that not everyone cares so much about the topic of this thread, and potentially more about the scientific issues surrounding it. Just because you like to reiterate that you still favour the shark every few months, doesn’t mean I have to do the same. That is, frankly, putting way too much emphasis on an opinion that is of no real concern or value to anyone else.

If I comment on "Stegosaurus vs T. rex", do you seriously think it is because I care about the outcome of that scenario? No. If I comment on dinosauria101’s size comparison showing a fictional size for Ceratosaurus compared to Daeodon, do I do that because I care about the outcome of a fictional fight between the two? No. This is not the fantasy section. I comment to point out something that can inform people about these animals. I have no problems whatsoever arguing "for" or "against" either "side", but seeing your and life’s posts here, in terms of listing arguments in favour of the shark, I’ve simply had my work cut out for me, and this has been the case since this forum was founded, by and large. Which doesn’t mean I have problems also addressing arguments in support of the whale that I find erraneous, as you will recall, for one as biased as I am, I have spend quite a bit of time voicing my disagreements with sam1 regarding locomotion and respiratory systems.

My arguments adhere to the scientific data, not my preconceived notions of which of these two is "superior".

I am not "denying" the possibility of the shark being possibly larger. I’m just also considering the possibility of the whale being possibly larger as well. Both exist. As you have consistently argued for the shark to be larger, and by and large ignored any or all of my points in criticism of these claims, of course I am more compelled to argue against that then for it (again, I’ve obviously had my work cut out for me arguing for how gigantic the shark is).

Of course I don’t share your opinion that the size of the largest isolated teeth is of any real relevance in answering that question, something we really don’t have to revisit yet again, as there is no new data with any impact on this whatsoever (if anything, the number of Livyatan sp. teeth recently described have reinforced that the specimen is probably a pretty typical size for its species).

That word, "denying" btw, a bit presumptuous, don’t you think? That sounds like I was "denying" evolution, or climate change, or gravity Even for those cases, use of the word "denying" is frequently criticized, despite being somewhat appropriate, because the things (at least the observational basis) being denied really are facts. You can "deny" that organisms change and adapt over time, that the earth is getting warmer, or that masses attract one another. You cannot "deny" a highly speculative size estimate with huge error margins.

But I am not the person here who is calling researchers "idiots" for publishing research at odds with my viewpoints, or not doing research on subjects more in line with my interest, so it’s more than a little puzzling you are busy criticizing me instead. Why is this? I wouldn’t want to go so far as to suggest this is primarily because of our disagreement, or some personal issue, but it seems hard to explain as being less a result of that than any actual bias I am supposed to have shown here.

I’ll give it two days for you to cool down, and suggest you do the same.