O. Megalodon, disproving scavenger theories

[prehistorican]

If Megalodon was really a scavenger, then it would have its dorsal fins pushed back and it would have a large upper lobe tail. It would feed off of carcasses on the sea floor. However, this sort of acceleration design is simply unfeasible for animals of such mass and has never evolved in animals that size. Fallen oceanic floor carcasses are also rare and hard to find, usually they are stripped of any valuable organic material before reaching the ocean floor.
Hypothetical Scavenging "Sand-Tiger" Megalodon (Acceleration)

This is a far more logical and feasible model which basically almost all of the scientific consensus has come to. A cruising, slightly more robust great white.
Scientific Consensus Body Type Megalodon (Cruising)

[creature386]

Jun 3, 2018 21:23:04 GMT 5 prehistorican said:

Jun 3, 2018 18:45:06 GMT 5 creature386 said:

First of all, I'm completely on your side. I agree that Hawthorne is nuts and your post is well-written. However, I take issue with one bit:What makes think more than half of Megalodons would have needed to be adults? This is inconsistent with the sample from the nursery study and that would require a very, very K-style reproduction strategy to be true.

I see, then what is the percentage of adults? 10-25% is what I would assume. 

I don't think we have enough data to answer that, but your percentage sounds intuitively correct.

[Infinity Blade]

On Animalia someone tried arguing that O. megalodon was a scavenger (or primarily a scavenger). How about addressing his stuff here too?

[prehistorican]

Jun 5, 2018 6:05:20 GMT 5 Infinity Blade said:

On Animalia someone tried arguing that O. megalodon was a scavenger (or primarily a scavenger). How about addressing his stuff here too?

Oh yeah the member Salvator Merinae, the one who tried arguing Megalodon grew up to 40 tons was inactive, and that Mosasaurs reached 30 tons. Also tried undersizing the maximum size of Megalodon as well. (Interesting note: Most Russian paleo fans usually heavily favor Mosasaurus against a Megalodon for some odd reason while undersizing the maximum side of the shark, I am not sure the reason behind this). I already disproved most of his points already, maybe there are one or two left, I'll try and take a look. Though I think he said Megalodons were more opportunistic than great whites, but he tried arguing that Megalodon was an inactive predator for an odd reason. He also stated macropredatory sharks are less successful at catching prey than other predators. (Not true at all, great whites have an 47% success rate!, compare that to singular lions of 17-19%, 48% is comparable to many predatory animals) experienced white sharks even have up to 80% kill rates, in my opinion that's pretty good.
www.discoverwildlife.com/animals/hunting-success-rates-how-predators-comparehttps://sharkresearch.rsmas.miami.edu/research/projects/great-white-predation
He also tried citing this EXACT Kronos Rising article, (LMAO )! Now that I have analytically refuted this, I could move onto his main "arguments" 
Due to these certain biases towards sharks and marine reptiles, I do not trust this guy all that much on the subject. But if time allows, I shall refute any shred of claims he has left.

[prehistorican]

Jun 5, 2018 3:53:52 GMT 5 creature386 said:

Jun 3, 2018 21:23:04 GMT 5 prehistorican said:

I see, then what is the percentage of adults? 10-25% is what I would assume. 

I don't think we have enough data to answer that, but your percentage sounds intuitively correct.

Doesn't matter that much, that is STILL in the tens of thousands probably. I do not think there are enough dead whales to sustain a population that large for millions of years? Do you think that there were enough dead whales per week to sustain THOUSANDS of adult Megalodon? NO WAY, that would be ridiculous, so it still remains clear that there were NOT enough dead whales to sustain a hypothetical scavenging adult Megalodon population.

[prehistorican]

GUYS HAHA! You aren't t gonna believe who Salvator Merinae cites for his other source! SALTWATER CROCODILE (Youtuber). The one who believes a T. rex can beat a Megalodon. The animator who also favors a Mosasaurus over a Megalodon. This guy is a shark hater! I can literally tell by looking at his fantasy piece of shit, ugly-ass drawings lined everywhere on his profile, must have spent hours working on some useless ms paint depictions. Basically this dude is a Phillip2001 with extreme bias against Megalodon and extreme bias towards saltwater crocodiles for people who need an introduction. On par or even worse (most likely far worse) than the infamous Max Hawthorne on reliability. This guy Saltwater Crocodile is F***ing hilarious oh dear, hahaha!

Next thing you know, he posts this: At this point, I'm not sure if Salvator is serious, or likes to defy scientific papers of Megalodon for his own fanboy reptilian fantasy.

There is a very good answer to all of these arguments here. Perhaps I will translate full atticle later. The author of this alternative view found a much more important problem in "otodus megalodon as scavenger" hypotisis than such fanatical charges as speculative estimates of Otodus megalodon size based on a single isolated tooth (not even on a full jaw) and poroportions of great white shark or unscientific statments . And this problem is that there are no any obligate scavengers larger than vultures on land or in water. Instead, O. megalodon may have been a very opportunistic predator with a large portion of carrion in the diet (large great white sharks are known to eat a big amount of carrion), but not an obligate scavenger. The proportion of whales in the O. megalodon diet could not be higher (or be lower due to proportionally less mobility) than the proportion of dolphins and seals in the diet of the great white sharks or tiger sharks, and other food items (eg, carrion and large fishes) could be a more important part in the diet of O. megalodon than live whales in many areas (as in large white sharks and tiger sharks).

But based on this material, now I will refute the myth that O. megalodon required 500 kg to 1000 kg of food per day. Translation from the article:

It should be noted that due to the low level of metabolism it (Otodus megalodon) needed a very small amount of food for an animal of such size. If we compare O. megalodon with the dogfish, that has a standard metabolic rate about 3 times lower than that of the mesotherm sharks, about 2 times lower than the usual ectothermic sharks like the lemon shark and 4 times lower than in crocodiles, energy consumption of O. megalodon will be around 4962155 kcal/month. With such food needs, O. megalodon will eat ~744 kg of whale blubber per month and ~8932 kg or ~19.4% of its body weight per year. At the same time I took the body mass of the O. megalodon for calculation at 46151 kg from Gottfried et al., that is based on a great white shark and can be overestimated even for the largest individuals. If we will feed O. megalodon not by whale fat but by cow bones, then it will needs to eat 4726 kg per month or 56710 kg per year (approximately 123% of their body mass). Of course, the energy consumption of O. megalodon will increase due to the short period of activity required for catching prey, in dogfish in such periods of activity the metabolic rate increases by about 2.75 times. But in all cases these energy consumption are simply miserable relative to those that would be expected, for example, from a 50-ton warm-blooded Livyatan melvillei.

Large animals tend to have an allometric decrease in relative metabolic rates and (on this basis) the required amount of food with an increase in size (just compare the shrew with the human). But if we take energy consumption of 943 kg great white shark (0.20 Kcal/kg/h) from this papper we get energy consumption of 50 tonnes O. megalodon around 240000 kcal/day and energy consumption of 50 tonnes sharkzilla around 480000 kcal/day. So, in this case, 50-ton O. megalodon will need to eat only 36 kg of whale blubber per day (1008 kg per month) or 229 kg of cow bones per day (6412 kg per month), and 100-ton ubershark wil need to eat only 72 kg of whale blubber per day (2016 kg per month) or 457 kg of cow bones per day (12796 kg per month).
But:

This value would be for the warm muscle and is a high estimate since the average over the whole fish, including colder and less active tissue, should be considerably lower.

For comparison, taking the metabolic needs of adult killer whales (30-35 kcal/kg/day) form this paper, an 50-ton Livyatan melvillei required about 1500000-1750000kcal per day (and needs to eat 225-263 kg of whale blubber per day or 6300-7364 kg per month).

[Grey]

The guy is contradictorial, if the shark had such low food requirements, in a marine environment filled with the most massive amount of large prey items ever, it would be even easier for it to grow huge, better than a higher metabolic mammal predator.

[prehistorican]

Jun 9, 2018 3:08:07 GMT 5 Grey said:

The guy is contradictorial, if the shark had such low food requirements, in a marine environment filled with the most massive amount of large prey items ever, it would be even easier for it to grow huge, better than a higher metabolic mammal predator.

Correct. I couldn't have put it a better way myself. I was trying to think of how his statement was wrong but this is what I was thinking in my head. 

[elosha11]

^With regard to adult v. juvenile population, I saw a recent study for great whites that surprised me as to few adults existed in Australia/New Zealand population compared to adults. Given man's impact, it's hard to know what this may imply with regard to Megalodon's adult/juvenile ratio throughout its existence. Probably not much, because this sobering study really points out how hard it is for adult great whites (in the era of mankind) to reach adulthood.

To quote from the study summary:

The status of great whites was classified as nationally endangered, with the total number of adult great whites in the waters of New Zealand and eastern Australia estimated at between 590 and 750. The total number including juveniles is estimated to be 5460.

The adult population is estimated at only around 11 to 14%. Dangerously low.

www.stuff.co.nz/science/105112605/great-white-numbers-low-basking-sharks-rapidly-decline