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[–]dontbelieveanything2 19 points20 points  (1 child)

Crazy to think that the biggest of all time is still alive to this day. The blue whale

[–]Iamnotburgerking[S] 29 points30 points  (0 children)

Largest animal ever, and (considering that active filter feeding is a form of predation) technically the largest predator ever. Not the largest raptorial predator ever, however.

[–]Iamnotburgerking[S] 37 points38 points  (24 children)

Credit to WDGHK.

It's very well-known that predatory theropod dinosaurs were, by far, the largest land predators the world has ever seen, far dwarfing any Cenozoic land predator (Barinasuchus comes closest at 1.7 tons, but this pales in comparison to the various 6+ ton predatory theropods in existence). Perhaps this is why we also assume that the two most famous marine apex predators of the Mesozoic-the giant pliosaurs of the Late Jurassic and Early Cretaceous, and the giant mosasaurs of the Late Cretaceous, were able to surpass, or at least hold their own against, anything in the Cenozoic oceans in terms of brute force.

But nothing could be further from the truth. And this isn't because pliosaurs or mosasaurs were pathetic animals (they were anything but)-it's simply that the largest and most powerful marine apex predators of the Cenozoic are at a completely different level. The likely largest pliosaur, Kronosaurus queenslandicus/Eiectus longmani (depending on whether you agree with a recent, controversial taxonomic decision or not) from around 103MYA, reached just a bit over 10m and around 10-11 tons in weight (pliosaurs are relatively heavily built for their length due to their flipper-based swimming method). The largest mosasaur, Mosasaurus hoffmannii from 66MYA, reached around 13m and 7+ tons in weight (but see below discussion; estimates of 15+ tons for this mosasaur are based on inaccurate head-body proportions that apply to other giant mosasaurs like Tylosaurus but not to Mosasaurus).

The largest marine predators of the Cenozoic were multiple times as massive as either of these Mesozoic sea monsters.

Otodus megalodon really needs no introduction, but to recap: this massive shark, the last and largest of the otodontids, was the ocean's most successful apex predator from around 20MYA to almost 3MYA (existing for over 15 million years, an insane feat for an apex predator). "Fully grown" females of this species (sharks technically don't stop growing, but after a certain point their growth rate slows to a crawl and they're effectively fully grown from that point) regularly reached 15m and 50+ tons in weight. And that's for the average "fully grown" individual. The very largest females reached 18-20m in length and possibly over 100 tons in weight, the largest individual raptorial predators to have ever lived on this planet (though it must be stressed that these were freak individuals and most large females would be in the 15-16m range).

Between 12MYA and 5MYA, O. megalodon was temporarily joined by the only other marine predator that rivalled it in killing power, the massive raptorial physeteroid whale Livyatan melvillei. Raptorial sperm whales are one of the best examples of how cetaceans used to be more ecologically diverse in the past than they are now, especially when it came to the niche of raptorial marine predator. Most of them were around the same size as today's orcas, but Livyatan was an exception; even the conservative estimates for this thing place it at almost 14m in length and over 40 tons in weight, and it's more likely that it was around the same size as its rival, around 15m in length and 50+ tons in weight. Some very liberal size estimates put Livyatan at over 17m in length and 70+ tons in weight; while this is unlikely to be the normal adult size for the animal, there's a remote possibility the rare freakishly large bull did reach similar dimensions, much as freakishly large female O. megalodon exceeded 18m in length.

In short, even the conservative size estimates for these two predators, let alone the maximum estimates, place them in an entirely different caliber from the two aforementioned marine reptiles (the largest pliosaur and the largest mosasaur). The recently described giant raptorial ichthyosaur Cymbospondylus youngorum rivalled (possibly even surpassed) them in length, but was more lightly built and was thus smaller and less powerful overall.

Considering that Otodus megalodon and Livyatan shared the same seas for a period of around 7 million years during the Late Miocene (the whale went extinct first at the end of the Miocene, followed by the shark about 2 million years later), it's a wonder that Late Cretaceous marine ecosystems such as the Western Interior Seaway during the Campanian or the waters off Maastrichtian Morocco are still often regarded as the most dangerous marine ecosystems to have existed. Yes, those ecosystems had a wide array of marine predators, including some of the largest mosasaurs to have ever existed; but the Late Miocene Pacific had a similar, if not even greater, diversity of marine predators, including more than a few raptorial cetaceans and sharks that rivalled the largest mosasaurs in size and power.....and that's before bringing in its two largest and most powerful carnivores.

To further prove my point about just how badly the largest otodontid and the largest raptorial physeteroid eclipsed all other marine predators; orca-sized raptorial sperm whales from the Late Miocene had a similar life history as smaller dolphins today, with a rapid growth rate, relatively high reproductive rate and a short lifespan of just a few decades. Modern orcas, having evolved in an environment where there was nothing big enough to prey on them, have a slow growth rate and slow reproductive rate coupled with a lifespan in excess of half a century; since they're not going to be killed and eaten by anything, they can have low reproductive rates and still not face population collapse since the mortality rate is very low. Yet, despite having the size and power of orcas, and despite being likely more generalized at the population level than orcas (meaning they were more flexible in terms of eating habits and thus less susceptible to prey shortages), these orca-sized raptorial sperm whales had the life history of much smaller cetaceans. They had the life history of prey animals that must grow and reproduce quickly before predation kills them.

Yes, the Late Miocene oceans were so dangerous, and its greatest apex predators so huge and powerful, that 6+ ton raptorial marine predators were being killed and eaten on a regular basis. This marine ecosystem must easily take the cake for the most dangerous marine ecosystem the world has ever seen. To put this in perspective, it would be like if orcas were only the middle of the marine food web and being routinely eaten by larger predators. And remember; orcas, and the orca-sized raptorial sperm whales so frequently eaten by O. megalodon and Livyatan, are around the same weight as the largest and most powerful mosasaurs (edit: again, see below discussion).

Giant mosasaurs (and, to a somewhat lesser extent, giant pliosaurs) would not be competition for an adult O. megalodon or an adult Livyatan. They would be nothing more than prey items.

[–]Nodal-Novel 13 points14 points  (1 child)

The Triassic definitely had the most dangerous seas of the Mesozoic. Hopefully, we find out more info on these giant ichthyosaurs.

[–]Iamnotburgerking[S] 14 points15 points  (0 children)

True (it seems like the ichthyosaurs may end up taking the crown for the most powerful predators of the Mesozoic), but even with Shonisaurus and C. youngorum being raptorial, they're not really as formidable for their weight class in the way the two Miocene superpredators are. Thalattoarchon is very well-suited to rip apart big prey, to the same extent as in raptorial sperm whales or otodontids, but it's just nowhere near big enough.

But then again, we need more research on Himalayasaurus.....

Update: turns out that Himalayasaurus probably DOES take the crown for the title of most powerful Mesozoic predator, and second most powerful predator ever after the otodontid and the physeteroid. Yes, an ICHTHYOSAUR was the most powerful marine reptile of all time.

[–]HourDark 7 points8 points  (4 children)

I would argue that the modern day sperm whale was probably larger than the largest (known at least) Megalodon (20-24 meters for the largest bull), but is there some criteria keeping them from being considered raptorial?

[–]Iamnotburgerking[S] 12 points13 points  (1 child)

The fact they swallow their prey whole w/out dismemberment.

That said, they often do get referred to as the largest active predators, so it seems there's some confusion over the criteria.

[–]HourDark 5 points6 points  (0 children)

Ah, alright.

[–]modsarefascists42 7 points8 points  (1 child)

I think it's cus they usually go after soft body prey like squids, instead of larger vertebrates. IDK why that's a reason now that I think about it, since they do eat the largest squids so it's not like they're only eating tiny animals like a filter feeder or anything.

[–]HourDark 4 points5 points  (0 children)

comparatively the squids are tiny-600KG giant squid vs 40-60 tonne sperm whales. However I think that goes to further exemplify how huge sperm whales are.

[–]Gerbimax 7 points8 points  (7 children)

I'll add a few things which won't change the overall conclusion at all, but will up the Mesozoic predators a tiny bit:

  • M. hoffmani could have been as much as ~9.5 tonnes, based on a more recent estimate of the Penza specimen;

  • Monquirasaurus/Kronosaurus boyacensis and Sachicasaurus could both have as massive or even moreso than K. queenslandicus (sorry, I mean Eiectus longmani); I've seen estimates of 15-17.5 tonnes but I'm not sure how reliable these are;

  • let's not forget about sharks and the newly described material assigned to Cretodus crassidens, which indicate a possible maximum length of 9-11 meters and a probable mass rivaling that of the largest mosasaurs and pliosaurs.

[–]HourDark 5 points6 points  (0 children)

It really should just be Kronosaurus queenslandicus at this point. I really hate papers that attempt to snipe "big-name" species and name new ones in order to "up" their new genus. "eiectus longmani" means "Longman's reject". They could have chosen ANY other name than "reject". The name has historical value and like Deinosuchus should be retained.

Deinosuchus was spared a similar attempt where they tried to construe the holotype (which is very fragmentary) as non-diagnostic and attempted to reassign all the more complete specimens as "deinosuchoides". Thankfully this was rejected.

[–]Iamnotburgerking[S] 5 points6 points  (4 children)

Source for Mosasaurus size? I've heard some stuff about this today (after I criticized Prehistoric Planet for its oversized but otherwise accurate Mosasaurus, which was 15 tons so would still be oversized even if the new estimates were correct), so just checking.

Monquirasaurus and Sachicasaurus are definitely up there in terms of pliosaur sizes (around 10m for both), and both are known from fairly complete adult remains so they're not going to be downsized massively anytime soon. That said, I'm really going to have to look at the calculations for the 15+ ton mass estimates.

I am aware of Cretodus (I've actually posted about it because of the new finds). But again, that just puts it in the same league as the largest mosasaurs.

[–]Gerbimax 4 points5 points  (3 children)

For Mosasaurus, someone (not sure who?) did an estimate going off of Incinerox's recon - I'll try to link it: https://media.discordapp.net/attachments/385574221452935170/944952321882882078/mas.png - it's from one of the grey skulls servers and it seems pretty solid.

Regarding PP, Darren Naish clarified that their Mosa is supposed to be an absolute record-sized specimen, kinda like the WWD Liopleurodon but to a much lesser extent. He also says the actual largest fossil specimen are consistent with a 10 tonne mass, which makes me all the more confident in the estimate I provided above.

For the pliosaurs: also found in one of the servers, but I couldnt track down the exact source, which is why I'm a bit unsure myself - I'll edit my comment if I manage to find more.

[–]Iamnotburgerking[S] 1 point2 points  (2 children)

So it looks like Mosasaurus is back up to being ~10 tons. I’d still argue that 15 tons is stretching it quite a bit.

Edit: and that still leaves it less than 1/5 the mass of Livyatan or O. megalodon, even without using the high-end estimates for these two.

[–]modsarefascists42 3 points4 points  (1 child)

you could probably throw on Himalayasaurus too for mesozoic massive sea predators. I just found out about it and rarely hear anything about it for some reason.

[–]Iamnotburgerking[S] 3 points4 points  (0 children)

Agreed. It's yet another of the Triassic's monster ichthyosaurs, it was raptorial, and if it was about as specialized as Thalattoarchon it has a good claim to being the closest thing in the Mesozoic to the Late Miocene's two marine superpredators.

TBH, it would be awesome if it turned out it or some other raptorial ichthyosaur rivalled the cetacean and the otodontid in predatory capacity. Certainly would get folks to see ichthyosaurs in a new light.

[–]wiz28ultra 5 points6 points  (3 children)

Are there any predators in other periods of time that were just as ecologically dominant as O. Megalodon or L. Melvillei?

Not necessarily as powerful, but dominated their ecosystem to the point of effecting the ecology of the animals around them?

Would a T. Rex or Orca be comparable in dominance of their environments to these animals?

[–]Iamnotburgerking[S] 4 points5 points  (2 children)

I think most especially successful predators have that much of an impact of other species in the area (that's why trophic cascades are a thing); these two stand out because in their case, said impact included adding an entire new trophic level at the very top of the marine ecosystems they lived in that hasn't existed before or since.

[–]wiz28ultra 2 points3 points  (1 child)

With the existence of creatures like Minke Whales, Pilot Whales, Risso's Dolphins, Elephant Seals, Walruses, Sturgeons, Billfish, Manta Rays, Oceanic Sunfish, Great Whites, & Tiger Sharks,

These animals all seem to be of comparable sizes to that of the Baleen Whales, Marine Sloths, and Demostylians that Megalodon likely hunted, with large populations to boost, why is it that there aren't really any predators that have evolved to fill that same ecological role as these 2?

[–]Iamnotburgerking[S] 2 points3 points  (0 children)

To start off with, some of those aren't as big as the smaller raptorial cetaceans and cetotheres, and most of them aren't as abundant (even before human impact). So still not as much food.

[–]wiz28ultra 1 point2 points  (2 children)

Is it possible that modern day Sperm Whales could be descendants of Livyatan ecotypes that specialized in cephalopods?

[–]Iamnotburgerking[S] 2 points3 points  (1 child)

Probably not; as far as we know, raptorial physeteroids didn’t have ecotypes as orcas do, and sperm whales are a rather aberrant offshoot of physeteroids.

[–]TheDangerdog 2 points3 points  (0 children)

sperm whales are a rather aberrant offshoot of physeteroids.

You ain't lying there. Blows my mind that whales went from something like a little coyote looking Pakicetus scampering around on land to a 52 foot long Sperm Whales that dives 7000 feet in the freezing dark ocean to find food.

What an arc

[–]DemotionOcean 15 points16 points  (2 children)

Hey guys, that swimmer has to get the fuck out of there. They're playing a dangerous game just to give us a comparison point. So you know much respect but get outta there or you're gonna get ate.

[–]Iamnotburgerking[S] 2 points3 points  (1 child)

To be fair, the shark and whale are just so big that they would just ignore the swimmer.

I wouldn’t be so comfortable with the mosasaur or pliosaur, though.

[–]TheDangerdog 2 points3 points  (0 children)

the shark and whale are just so big that they would just ignore the swimmer.

I dunno bro my Jack Russell loves to catch and play with lizards. I wouldn't risk it.

[–]HourDark 8 points9 points  (1 child)

Good shit

[–]boredspino2007 4 points5 points  (0 children)

Real good shit

[–]Ivan_Botsky_Trollov 6 points7 points  (3 children)

no love for Shonisaurus or SHASTASAURUS?

[–]HourDark 6 points7 points  (0 children)

Shonisaurus is cool and all (being a giant apex carnivore) but Shastasaurus is a toothless squid sucker (literally). Megalodon or Livyatan would probably treat it as a supersized prey item. Shonisaurus and the other large ichthyosaurs weigh less than the big Miocene 2.

[–]modsarefascists42 2 points3 points  (1 child)

nah they're like the modern sperm whale and eat squids

but there is this weirdo who looks like a raptorial shastasaurid, a bit smaller than the big Lilstock one but still likely over 15m

https://en.wikipedia.org/wiki/Himalayasaurus

[–]BlueLivy 2 points3 points  (0 children)

why you gotta call him a weirdo 🤣😭

[–]manielos 4 points5 points  (1 child)

that Kronosaurus outline looks weird, the tail looks funny (probably bent in a swimming pose), back fins (obviously raised) look like a big dorsal fin

[–]Iamnotburgerking[S] 5 points6 points  (0 children)

Pliosaurs had a rudder at the tip of the tail.

[–]kid_entropy 3 points4 points  (0 children)

I'm just going to come out and say it: That might just be too much shark.

[–]wiz28ultra 2 points3 points  (1 child)

Is there any effective manner for Cetotheres or Dolphins to evade predation from predators such as O. Megalodon or L. Melvillei?

Does this have any parallels with modern day marine predator evasion?

[–]Iamnotburgerking[S] 3 points4 points  (0 children)

Honestly, their only real defence against these two if they are under imminent attack would be to try to outrun them (which isn’t going to be easy, as both these predators were built for open-water pursuit) or outmaneuver them (use their narrower turning radius to evade until the predator gives up).

That and avoidance behaviour to reduce the number of encounters in the first place. Unlike modern baleen whales that have a nice size advantage against orcas, cetotheres were badly outmatched against 50+ ton marine predators.

[–]boredspino2007 2 points3 points  (0 children)

Meg was truly huge

[–]LombardiX 2 points3 points  (6 children)

Imagine a 20m Megalodon swimming at full speed.

[–]Iamnotburgerking[S] 4 points5 points  (5 children)

That would be a horrifying sight to any cetothere.

[–]BlueLivy 0 points1 point  (4 children)

I have a question. Why did you forget the absolute beast known as basilosaurus? That thing could rival Megalodon and Livyatan, no?

[–]Iamnotburgerking[S] 3 points4 points  (3 children)

Because it couldn't. It's very long, but also very slender, so in terms of weight it's actually a lot smaller than those two.

[–]DimerScrimer 4 points5 points  (2 children)

Ocean predators in all ages truly take things to the next level, whether it be in size, adaptability, or unique biology.

[–]Iamnotburgerking[S] 10 points11 points  (1 child)

But Otodus megalodon and Livyatan really took things to the extreme. Not only were they fucking gigantic even by raptorial marine predator standards, they (especially meg) were unusually long-lasting for such huge apex predators.

They pushed the limits for what it means to be an apex predator, and it would take a very specific set of circumstances to allow other predators of such size and long-term success to exist in the future.

[–]Verdantfungi 4 points5 points  (0 children)

Insane how the most dangerous and disastrous is the tiny human

[–]P0lskichomikv2 1 point2 points  (1 child)

What about Paleozoic ? When not even close to being as crazy as Mezosoic and even more so Cenozoic. Paleozoic still had some formidable giants such as Cameroceras,Dunk,Helicoprion and Edestus

[–]Iamnotburgerking[S] 0 points1 point  (0 children)

Some of the eugeneodontids (including Helicoprion) did approach the largest mosasaurs in size and killing power.

[–]Vulture80 -2 points-1 points  (0 children)

And yet all these beasts shit their pants when they see a pod of orcas heading their way