Megalodon vs. Livyatan melvillei

[Grey]

Once I get pictures of the model I ll post them.

Yes, I had understood what you meant, the point is a 50 tonnes predatory fish is already hard to comprehend, I think a simulation such as the one made by Ferrón for extrapolating the maximum weight of Leedsichthys would be useful.

By the way, in the same way, perhaps you could do the same with the movie Mec model :







The beast is a real blimp.

[theropod]

That one’s about 80t (78 to be exact) when altering the dorsal silhouette. Like one of the previous ones, this one would be even heavier if it had an appropriately wide caudal peduncle, which is strangely thin as portrayed here, especially compared to the width in the pectoral region (I guess the makers wanted to emphasize the jaws, not the tail, but still this looks almost comical in dorsal view, as if the tail of a much smaller shark had been blended with the front half of a giant meg), but the rest is way too deep- and also wide-bodied. So all in all, quite bad, especially the dorsal/ventral silhouette (here→ and here→ is what it probably should look like, and what I based the model on).

[Grey]

Yup I know it is discutable but I was rather pleased with it. Oddly, I thought the peduncle to be appropriately massive for a shark body this size.

All in all this means the 23 m scaled big shark of the movie approaches 150 tonnes...

[theropod]

Appropriately monstrous for a monster movie.

In lateral view, which is probably what’s more commonly shown, the peduncle looks easily thick enough. The thing that most people don’t get is that it’s supposed to be wide, not tall. Which is why most people draw their caudal peduncles too tall to make it look more robust, but most dorsal-view reconstructions on the other hand make it too narrow. The opposite would be expected in a real shark, if anything meg would have a proportionately wider peduncle.

[Grey]

I was exactly talking about the width. Indeed, many forget the peduncle is much wider than deep.

My main interrogation is about Kent restoration. Since years they argue to make meg less bulky than Gottfried's but either the first artistic restoration and the reported measurements of the new life size sculpture appear to depict a heavy animal, your works confirm it. We will discuss this once it is mounted..

[theropod]

I think without a volumetric model it is easy to be misled about something like this. Gottfried et al.’s reconstruction is bulky, but it looks even bulkier than it is due to the pug nose and massive, protruding jaw structure not seen in most other depictions, which automatically makes it appear more square-ended and less streamlined.

[Grey]

Yes I had this in mind.
On a side note, the making of from where I took the pictures of the movie monster, they say the basis was the porbeagle.

[theropod]

Well, there’s a porbeagle drawing in the book I posted as well, doesn’t really look to be much closer to me (Lamna also has the broad caudal keels, which seems to be standard for fast-swimming, pelagic sharks). The head in fact reminds me more of a carcharhiniform, and of course partly a hexanchiform due to the additional gill slits.

[Grey]

I think I ve there was also some tiger and bull shark influence for the head.

I think more gills is an interesting idea to ponder about. Giant otodontids in the 10-60 tonnes range may have had some anatomical novelties or specificities to grow that gigantic and still being gilled active predators.

Here is a link about the movie Meg.

youtu.be/WXQEENGZYIw

[theropod]

It is an interesting idea, that’s true, but doesn’t seem like the most likely option an actual giant shark would use to achieve an increased area for oxygen uptake, at least not the first such adaptation that we would see.

Extant sevengill sharks don’t seem to be more active, or for that matter, require more oxygen than other large-sized predatory sharks. Extant giant-sized sharks, whale and basking sharks, don’t have additional gills. But at least in basking sharks, the gills seem to be dorsoventrally more expansive than in smaller sharks,

So I think hypothesizing additional gills, especially one more than the maximum number found among all extant sharks, is a bit of a stretch from a scientific point of view, though certainly fine for a movie.

[Grey]

It could be additional gills or something else. All in all, there may have been some novelties in this specific lineage.

Sevengill sharks usually live in deepwater, this might help them to get more oxygen (?).

I think basking sharks are a good hint at this.

Are you sure the third model (derived from Kent updates) should really reflect a massive 90 tonnes at 17 m ? I tend to see this model as the most rigorous to date, awaiting for the life sized one, so I m a bit surprised of such a figure.

Also, I miscalculated, if the movie Meg is 78 tonnes at 17 m, the 23 m one is thus actually blue whale like in body mass at 190 tonnes.

[dinosauria101]

I apologize if this was posted (who has time to read through 83 pages quickly?), but here's something from the Carnivora thread about Livyatan, just for reference. Seems like it had a less impressive gape than its foe

[theropod]

Nobody would be surprised that an odontocete would have achieved lower gape angles than a shark, but there’s no reason to believe that picture has anything to do with its real gape.

[dinosauria101]

Oh, just thought it might help. Don't mind any errors, I know less about Livyatan to a greater degree than your lack of interest on non-sympatric AvA (and that say a lot)

[theropod]

Grey : Yes. I just tried to replicate my result again and got something very similar (86t, the first was 89), still over 60% heavier than it should be based on scaling equations and well over ten tons heavier than even a right whale at the same length (Lockyer 1976).
The body depth measured right behind the pectoral fin in this model is 3.8m, it would be just 2.9m according to my 52 ton model, and 3.0m according to the 57 ton one. That again gives us a body mass at least about 60% greater.

Of course this assumes the body width and depth are scaled up in equal proportions, without a corresponding top or bottom view there’s no way of inferring directly what the artist had in mind while doing the reconstruction, or whether they had anything in mind at all for that matter.

But the default assumption is to assume it was as much more robust in other views as it was in side view. Lateral view, at any rate, reflects how much more bulky it looks, so no matter what other assumptions are made but not illustrated, that’s the impression the viewer gets from looking at the reconstruction, which is a misleading one.

dinosauria101 : I know that picture, as I expect do most others here. No idea why people on carnivora seem to assume it implies any scientific findings on the maximum achievable gape angle though, because it does not, there has been no study on the jaw mechanics of Livyatan, there aren’t even concrete data on the gape of extant odontocetes. Livyatan certainly did have a smaller gape than megalodon, but that’s because of the extreme gape angles sharks can achieve, well in excess of most other animals, not because we know anything specific about the gape of Livyatan.


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Lockyer, C. 1976. Body weights of some species of large whales. ICES Journal of Marine Science 36 (3): 259–273.

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